ISTQB_CTFL_Syllabus-v4.0_removed.pdf

Certified Tester Foundation Level 1. Fundamentals of Testing – 180 minutes Keywords coverage, debugging, defect, error, failure, quality, quality assurance, root cause, test analysis, test basis, test case, test completion, test condition, test control, test data, test design, test execution, test implementation, test monitoring, test object, test objective, test planning, test procedure, test result, testing, testware, validation, verification Learning Objectives for Chapter 1: 1.1 What is Testing? FL-1.1.1 (K1) Identify typical test objectives FL-1.1.2 (K2) Differentiate testing from debugging 1.2 Why is Testing Necessary? FL-1.2.1 (K2) Exemplify why testing is necessary FL-1.2.2 (K1) Recall the relation between testing and quality assurance FL-1.2.3 (K2) Distinguish between root cause, error, defect, and failure 1.3 Testing Principles FL-1.3.1 (K2) Explain the seven testing principles 1.4 Test Activities, Testware and Test Roles FL-1.4.1 (K2) Summarize the different test activities and tasks FL-1.4.2 (K2) Explain the impact of context on the test process FL-1.4.3 (K2) Differentiate the testware that supports the test activities FL-1.4.4 (K2) Explain the value of maintaining traceability FL-1.4.5 (K2) Compare the different roles in testing 1.5 Essential Skills and Good Practices in Testing FL-1.5.1 (K2) Give examples of the generic skills required for testing FL-1.5.2 (K1) Recall the advantages of the whole team approach FL-1.5.3 (K2) Distinguish the benefits and drawbacks of independence of testing v4.0 Page 14 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 1.1. What is Testing? Software systems are an integral part of our daily life. Most people have had experience with software that did not work as expected. Software that does not work correctly can lead to many problems, including loss of money, time or business reputation, and, in extreme cases, even injury or death. Software testing assesses software quality and helps reducing the risk of software failure in operation. Software testing is a set of activities to discover defects and evaluate the quality of software artifacts. These artifacts, when being tested, are known as test objects. A common misconception about testing is that it only consists of executing tests (i.e., running the software and checking the test results). However, software testing also includes other activities and must be aligned with the software development lifecycle (see chapter 2). Another common misconception about testing is that testing focuses entirely on verifying the test object. Whilst testing involves verification, i.e., checking whether the system meets specified requirements, it also involves validation, which means checking whether the system meets users’ and other stakeholders’ needs in its operational environment. Testing may be dynamic or static. Dynamic testing involves the execution of software, while static testing does not. Static testing includes reviews (see chapter 3) and static analysis. Dynamic testing uses different types of test techniques and test approaches to derive test cases (see chapter 4). Testing is not only a technical activity. It also needs to be properly planned, managed, estimated, monitored and controlled (see chapter 5). Testers use tools (see chapter 6), but it is important to remember that testing is largely an intellectual activity, requiring the testers to have specialized knowledge, use analytical skills and apply critical thinking and systems thinking (Myers 2011, Roman 2018). The ISO/IEC/IEEE 29119-1 standard provides further information about software testing concepts. 1.1.1. Test Objectives The typical test objectives are: Evaluating work products such as requirements, user stories, designs, and code Triggering failures and finding defects Ensuring required coverage of a test object Reducing the level of risk of inadequate software quality Verifying whether specified requirements have been fulfilled Verifying that a test object complies with contractual, legal, and regulatory requirements Providing information to stakeholders to allow them to make informed decisions Building confidence in the quality of the test object Validating whether the test object is complete and works as expected by the stakeholders Objectives of testing can vary, depending upon the context, which includes the work product being tested, the test level, risks, the software development lifecycle (SDLC) being followed, and factors related to the business context, e.g., corporate structure, competitive considerations, or time to market. v4.0 Page 15 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 1.1.2. Testing and Debugging Testing and debugging are separate activities. Testing can trigger failures that are caused by defects in the software (dynamic testing) or can directly find defects in the test object (static testing). When dynamic testing (see chapter 4) triggers a failure, debugging is concerned with finding causes of this failure (defects), analyzing these causes, and eliminating them. The typical debugging process in this case involves: Reproduction of a failure Diagnosis (finding the root cause) Fixing the cause Subsequent confirmation testing checks whether the fixes resolved the problem. Preferably, confirmation testing is done by the same person who performed the initial test. Subsequent regression testing can also be performed, to check whether the fixes are causing failures in other parts of the test object (see section 2.2.3 for more information on confirmation testing and regression testing). When static testing identifies a defect, debugging is concerned with removing it. There is no need for reproduction or diagnosis, since static testing directly finds defects, and cannot cause failures (see chapter 3). 1.2. Why is Testing Necessary? Testing, as a form of quality control, helps in achieving the agreed upon goals within the set scope, time, quality, and budget constraints. Testing’s contribution to success should not be restricted to the test team activities. Any stakeholder can use their testing skills to bring the project closer to success. Testing components, systems, and associated documentation helps to identify defects in software, 1.2.1. Testing’s Contributions to Success Testing provides a cost-effective means of detecting defects. These defects can then be removed (by debugging – a non-testing activity), so testing indirectly contributes to higher quality test objects. Testing provides a means of directly evaluating the quality of a test object at various stages in the SDLC. These measures are used as part of a larger project management activity, contributing to decisions to move to the next stage of the SDLC, such as the release decision. Testing provides users with indirect representation on the development project. Testers ensure that their understanding of users’ needs are considered throughout the development lifecycle. The alternative is to involve a representative set of users as part of the development project, which is not usually possible due to the high costs and lack of availability of suitable users. Testing may also be required to meet contractual or legal requirements, or to comply with regulatory standards. 1.2.2. Testing and Quality Assurance (QA) While people often use the terms “testing” and “quality assurance” (QA) interchangeably, testing and QA are not the same. Testing is a form of quality control (QC). v4.0 Page 16 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level QC is a product-oriented, corrective approach that focuses on those activities supporting the achievement of appropriate levels of quality. Testing is a major form of quality control, while others include formal methods (model checking and proof of correctness), simulation and prototyping. QA is a process-oriented, preventive approach that focuses on the implementation and improvement of processes. It works on the basis that if a good process is followed correctly, then it will generate a good product. QA applies to both the development and testing processes, and is the responsibility of everyone on a project. Test results are used by QA and QC. In QC they are used to fix defects, while in QA they provide feedback on how well the development and test processes are performing. 1.2.3. Errors, Defects, Failures, and Root Causes Human beings make errors (mistakes), which produce defects (faults, bugs), which in turn may result in failures. Humans make errors for various reasons, such as time pressure, complexity of work products, processes, infrastructure or interactions, or simply because they are tired or lack adequate training. Defects can be found in documentation, such as a requirements specification or a test script, in source code, or in a supporting artifact such as a build file. Defects in artifacts produced earlier in the SDLC, if undetected, often lead to defective artifacts later in the lifecycle. If a defect in code is executed, the system may fail to do what it should do, or do something it shouldn’t, causing a failure. Some defects will always result in a failure if executed, while others will only result in a failure in specific circumstances, and some may never result in a failure. Errors and defects are not the only cause of failures. Failures can also be caused by environmental conditions, such as when radiation or electromagnetic field cause defects in firmware. A root cause is a fundamental reason for the occurrence of a problem (e.g., a situation that leads to an error). Root causes are identified through root cause analysis, which is typically performed when a failure occurs or a defect is identified. It is believed that further similar failures or defects can be prevented or their frequency reduced by addressing the root cause, such as by removing it. 1.3. Testing Principles A number of testing principles offering general guidelines applicable to all testing have been suggested over the years. This syllabus describes seven such principles. 1. Testing shows the presence, not the absence of defects. Testing can show that defects are present in the test object, but cannot prove that there are no defects (Buxton 1970). Testing reduces the probability of defects remaining undiscovered in the test object, but even if no defects are found, testing cannot prove test object correctness. 2. Exhaustive testing is impossible. Testing everything is not feasible except in trivial cases (Manna 1978). Rather than attempting to test exhaustively, test techniques (see chapter 4), test case prioritization (see section 5.1.5), and risk-based testing (see section 5.2), should be used to focus test efforts. 3. Early testing saves time and money. Defects that are removed early in the process will not cause subsequent defects in derived work products. The cost of quality will be reduced since fewer failures will occur later in the SDLC (Boehm 1981). To find defects early, both static testing (see chapter 3) and dynamic testing (see chapter 4) should be started as early as possible. 4. Defects cluster together. A small number of system components usually contain most of the defects discovered or are responsible for most of the operational failures (Enders 1975). This phenomenon is an v4.0 Page 17 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level illustration of the Pareto principle. Predicted defect clusters, and actual defect clusters observed during testing or in operation, are an important input for risk-based testing (see section 5.2). 5. Tests wear out. If the same tests are repeated many times, they become increasingly ineffective in detecting new defects (Beizer 1990). To overcome this effect, existing tests and test data may need to be modified, and new tests may need to be written. However, in some cases, repeating the same tests can have a beneficial outcome, e.g., in automated regression testing (see section 2.2.3). 6. Testing is context dependent. There is no single universally applicable approach to testing. Testing is done differently in different contexts (Kaner 2011). 7. Absence-of-defects fallacy. It is a fallacy (i.e., a misconception) to expect that software verification will ensure the success of a system. Thoroughly testing all the specified requirements and fixing all the defects found could still produce a system that does not fulfill the users’ needs and expectations, that does not help in achieving the customer’s business goals, and that is inferior compared to other competing systems. In addition to verification, validation should also be carried out (Boehm 1981). 1.4. Test Activities, Testware and Test Roles Testing is context dependent, but, at a high level, there are common sets of test activities without which testing is less likely to achieve test objectives. These sets of test activities form a test process. The test process can be tailored to a given situation based on various factors. Which test activities are included in this test process, how they are implemented, and when they occur is normally decided as part of the test planning for the specific situation (see section 5.1). The following sections describe the general aspects of this test process in terms of test activities and tasks, the impact of context, testware, traceability between the test basis and testware, and testing roles. The ISO/IEC/IEEE 29119-2 standard provides further information about test processes. 1.4.1. Test Activities and Tasks A test process usually consists of the main groups of activities described below. Although many of these activities may appear to follow a logical sequence, they are often implemented iteratively or in parallel. These testing activities usually need to be tailored to the system and the project. Test planning consists of defining the test objectives and then selecting an approach that best achieves the objectives within the constraints imposed by the overall context. Test planning is further explained in section 5.1. Test monitoring and control. Test monitoring involves the ongoing checking of all test activities and the comparison of actual progress against the plan. Test control involves taking the actions necessary to meet the objectives of testing. Test monitoring and control are further explained in section 5.3. Test analysis includes analyzing the test basis to identify testable features and to define and prioritize associated test conditions, together with the related risks and risk levels (see section 5.2). The test basis and the test objects are also evaluated to identify defects they may contain and to assess their testability. Test analysis is often supported by the use of test techniques (see chapter 4). Test analysis answers the question “what to test?” in terms of measurable coverage criteria. Test design includes elaborating the test conditions into test cases and other testware (e.g., test charters). This activity often involves the identification of coverage items, which serve as a guide to specify test case inputs. Test techniques (see chapter 4) can be used to support this activity. Test design v4.0 Page 18 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level also includes defining the test data requirements, designing the test environment and identifying any other required infrastructure and tools. Test design answers the question “how to test?”. Test implementation includes creating or acquiring the testware necessary for test execution (e.g., test data). Test cases can be organized into test procedures and are often assembled into test suites. Manual and automated test scripts are created. Test procedures are prioritized and arranged within a test execution schedule for efficient test execution (see section 5.1.5). The test environment is built and verified to be set up correctly. Test execution includes running the tests in accordance with the test execution schedule (test runs). Test execution may be manual or automated. Test execution can take many forms, including continuous testing or pair testing sessions. Actual test results are compared with the expected results. The test results are logged. Anomalies are analyzed to identify their likely causes. This analysis allows us to report the anomalies based on the failures observed (see section 5.5). Test completion activities usually occur at project milestones (e.g., release, end of iteration, test level completion) for any unresolved defects, change requests or product backlog items created. Any testware that may be useful in the future is identified and archived or handed over to the appropriate teams. The test environment is shut down to an agreed state. The test activities are analyzed to identify lessons learned and improvements for future iterations, releases, or projects (see section 2.1.6). A test completion report is created and communicated to the stakeholders. 1.4.2. Test Process in Context Testing is not performed in isolation. Test activities are an integral part of the development processes carried out within an organization. Testing is also funded by stakeholders and its final goal is to help fulfill the stakeholders’ business needs. Therefore, the way the testing is carried out will depend on a number of contextual factors including: Stakeholders (needs, expectations, requirements, willingness to cooperate, etc.) Team members (skills, knowledge, level of experience, availability, training needs, etc.) Business domain (criticality of the test object, identified risks, market needs, specific legal regulations, etc.) Technical factors (type of software, product architecture, technology used, etc.) Project constraints (scope, time, budget, resources, etc.) Organizational factors (organizational structure, existing policies, practices used, etc.) Software development lifecycle (engineering practices, development methods, etc.) Tools (availability, usability, compliance, etc.) These factors will have an impact on many test-related issues, including: test strategy, test techniques used, degree of test automation, required level of coverage, level of detail of test documentation, reporting, etc. 1.4.3. Testware Testware is created as output work products from the test activities described in section 1.4.1. There is a significant variation in how different organizations produce, shape, name, organize and manage their v4.0 Page 19 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level work products. Proper configuration management (see section 5.4) ensures consistency and integrity of work products. The following list of work products is not exhaustive: Test planning work products include: test plan, test schedule, risk register, and entry and exit criteria (see section 5.1). Risk register is a list of risks together with risk likelihood, risk impact and information about risk mitigation (see section 5.2). Test schedule, risk register and entry and exit criteria are often a part of the test plan. Test monitoring and control work products include: test progress reports (see section 5.3.2), documentation of control directives (see section 5.3) and risk information (see section 5.2). Test analysis work products include: (prioritized) test conditions (e.g., acceptance criteria, see section 4.5.2), and defect reports regarding defects in the test basis (if not fixed directly). Test design work products include: (prioritized) test cases, test charters, coverage items, test data requirements and test environment requirements. Test implementation work products include: test procedures, automated test scripts, test suites, test data, test execution schedule, and test environment elements. Examples of test environment elements include: stubs, drivers, simulators, and service virtualizations. Test execution work products include: test logs, and defect reports (see section 5.5). Test completion work products include: test completion report (see section 5.3.2), action items for improvement of subsequent projects or iterations, documented lessons learned, and change requests (e.g., as product backlog items). 1.4.4. Traceability between the Test Basis and Testware In order to implement effective test monitoring and control, it is important to establish and maintain traceability throughout the test process between the test basis elements, testware associated with these elements (e.g., test conditions, risks, test cases), test results, and detected defects. Accurate traceability supports coverage evaluation, so it is very useful if measurable coverage criteria are defined in the test basis. The coverage criteria can function as key performance indicators to drive the activities that show to what extent the test objectives have been achieved (see section 1.1.1). For example: Traceability of test cases to requirements can verify that the requirements are covered by test cases. Traceability of test results to risks can be used to evaluate the level of residual risk in a test object. In addition to evaluating coverage, good traceability makes it possible to determine the impact of changes, facilitates test audits, and helps meet IT governance criteria. Good traceability also makes test progress and completion reports more easily understandable by including the status of test basis elements. This can also assist in communicating the technical aspects of testing to stakeholders in an understandable manner. Traceability provides information to assess product quality, process capability, and project progress against business goals. v4.0 Page 20 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 1.4.5. Roles in Testing In this syllabus, two principal roles in testing are covered: a test management role and a testing role. The activities and tasks assigned to these two roles depend on factors such as the project and product context, the skills of the people in the roles, and the organization. The test management role takes overall responsibility for the test process, test team and leadership of the test activities. The test management role is mainly focused on the activities of test planning, test monitoring and control and test completion. The way in which the test management role is carried out varies depending on the context. For example, in Agile software development, some of the test management tasks may be handled by the Agile team. Tasks that span multiple teams or the entire organization may be performed by test managers outside of the development team. The testing role takes overall responsibility for the engineering (technical) aspect of testing. The testing role is mainly focused on the activities of test analysis, test design, test implementation and test execution. Different people may take on these roles at different times. For example, the test management role can be performed by a team leader, by a test manager, by a development manager, etc. It is also possible for one person to take on the roles of testing and test management at the same time. 1.5. Essential Skills and Good Practices in Testing Skill is the ability to do something well that comes from one’s knowledge, practice and aptitude. Good testers should possess some essential skills to do their job well. Good testers should be effective team players and should be able to perform testing on different levels of test independence. 1.5.1. Generic Skills Required for Testing While being generic, the following skills are particularly relevant for testers: Testing knowledge (to increase effectiveness of testing, e.g., by using test techniques) Thoroughness, carefulness, curiosity, attention to details, being methodical (to identify defects, especially the ones that are difficult to find) Good communication skills, active listening, being a team player (to interact effectively with all stakeholders, to convey information to others, to be understood, and to report and discuss defects) Analytical thinking, critical thinking, creativity (to increase effectiveness of testing) Technical knowledge (to increase efficiency of testing, e.g., by using appropriate test tools) Domain knowledge (to be able to understand and to communicate with end users/business representatives) Testers are often the bearers of bad news. It is a common human trait to blame the bearer of bad news. This makes communication skills crucial for testers. Communicating test results may be perceived as criticism of the product and of its author. Confirmation bias can make it difficult to accept information that disagrees with currently held beliefs. Some people may perceive testing as a destructive activity, even though it contributes greatly to project success and product quality. To try to improve this view, information about defects and failures should be communicated in a constructive way. v4.0 Page 21 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 1.5.2. Whole Team Approach One of the important skills for a tester is the ability to work effectively in a team context and to contribute positively to the team goals. The whole team approach – a practice coming from Extreme Programming (see section 2.1) – builds upon this skill. In the whole-team approach any team member with the necessary knowledge and skills can perform any task, and everyone is responsible for quality. The team members share the same workspace (physical or virtual), as co-location facilitates communication and interaction. The whole team approach improves team dynamics, enhances communication and collaboration within the team, and creates synergy by allowing the various skill sets within the team to be leveraged for the benefit of the project. Testers work closely with other team members to ensure that the desired quality levels are achieved. This includes collaborating with business representatives to help them create suitable acceptance tests and working with developers to agree on the test strategy and decide on test automation approaches. Testers can thus transfer testing knowledge to other team members and influence the development of the product. Depending on the context, the whole team approach may not always be appropriate. For instance, in some situations, such as safety-critical, a high level of test independence may be needed. 1.5.3. Independence of Testing A certain degree of independence makes the tester more effective at finding defects due to differences between the author’s and the tester’s cognitive biases (cf. Salman 1995). Independence is not, however, a replacement for familiarity, e.g., developers can efficiently find many defects in their own code. Work products can be tested by their author (no independence), by the author's peers from the same team (some independence), by testers from outside the author's team but within the organization (high independence), or by testers from outside the organization (very high independence). For most projects, it is usually best to carry out testing with multiple levels of independence (e.g., developers performing component and component integration testing, test team performing system and system integration testing, and business representatives performing acceptance testing). The main benefit of independence of testing is that independent testers are likely to recognize different kinds of failures and defects compared to developers because of their different backgrounds, technical perspectives, and biases. Moreover, an independent tester can verify, challenge, or disprove assumptions made by stakeholders during specification and implementation of the system. However, there are also some drawbacks. Independent testers may be isolated from the development team, which may lead to a lack of collaboration, communication problems, or an adversarial relationship with the development team. Developers may lose a sense of responsibility for quality. Independent testers may be seen as a bottleneck or be blamed for delays in release. v4.0 Page 22 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 2. Testing Throughout the Software Development Lifecycle – 130 minutes Keywords acceptance testing, black-box testing, component integration testing, component testing, confirmation testing, functional testing, integration testing, maintenance testing, non-functional testing, regression testing, shift-left, system integration testing, system testing, test level, test object, test type, white-box testing Learning Objectives for Chapter 2: 2.1 Testing in the Context of a Software Development Lifecycle FL-2.1.1 (K2) Explain the impact of the chosen software development lifecycle on testing FL-2.1.2 (K1) Recall good testing practices that apply to all software development lifecycles FL-2.1.3 (K1) Recall the examples of test-first approaches to development FL-2.1.4 (K2) Summarize how DevOps might have an impact on testing FL-2.1.5 (K2) Explain the shift-left approach FL-2.1.6 (K2) Explain how retrospectives can be used as a mechanism for process improvement 2.2 Test Levels and Test Types FL-2.2.1 (K2) Distinguish the different test levels FL-2.2.2 (K2) Distinguish the different test types FL-2.2.3 (K2) Distinguish confirmation testing from regression testing 2.3 Maintenance Testing FL-2.3.1 (K2) Summarize maintenance testing and its triggers v4.0 Page 23 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 2.1. Testing in the Context of a Software Development Lifecycle A software development lifecycle (SDLC) model is an abstract, high-level representation of the software development process. A SDLC model defines how different development phases and types of activities performed within this process relate to each other, both logically and chronologically. Examples of SDLC models include: sequential development models (e.g., waterfall model, V-model), iterative development models (e.g., spiral model, prototyping), and incremental development models (e.g., Unified Process). Some activities within software development processes can also be described by more detailed software development methods and Agile practices. Examples include: acceptance test-driven development (ATDD), behavior-driven development (BDD), domain-driven design (DDD), extreme programming (XP), feature-driven development (FDD), Kanban, Lean IT, Scrum, and test-driven development (TDD). 2.1.1. Impact of the Software Development Lifecycle on Testing Testing must be adapted to the SDLC to succeed. The choice of the SDLC impacts on the: Scope and timing of test activities (e.g., test levels and test types) Level of detail of test documentation Choice of test techniques and test approach Extent of test automation Role and responsibilities of a tester In sequential development models, in the initial phases testers typically participate in requirement reviews, test analysis, and test design. The executable code is usually created in the later phases, so typically dynamic testing cannot be performed early in the SDLC. In some iterative and incremental development models, it is assumed that each iteration delivers a working prototype or product increment. This implies that in each iteration both static and dynamic testing may be performed at all test levels. Frequent delivery of increments requires fast feedback and extensive regression testing. Agile software development assumes that change may occur throughout the project. Therefore, lightweight work product documentation and extensive test automation to make regression testing easier are favored in agile projects. Also, most of the manual testing tends to be done using experience-based test techniques (see Section 4.4) that do not require extensive prior test analysis and design. 2.1.2. Software Development Lifecycle and Good Testing Practices Good testing practices, independent of the chosen SDLC model, include the following: For every software development activity, there is a corresponding test activity, so that all development activities are subject to quality control Different test levels (see chapter 2.2.1) have specific and different test objectives, which allows for testing to be appropriately comprehensive while avoiding redundancy Test analysis and design for a given test level begins during the corresponding development phase of the SDLC, so that testing can adhere to the principle of early testing (see section 1.3) v4.0 Page 24 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Testers are involved in reviewing work products as soon as drafts of this documentation are available, so that this earlier testing and defect detection can support the shift-left strategy (see section 2.1.5) 2.1.3. Testing as a Driver for Software Development TDD, ATDD and BDD are similar development approaches, where tests are defined as a means of directing development. Each of these approaches implements the principle of early testing (see section 1.3) and follows a shift-left approach (see section 2.1.5), since the tests are defined before the code is written. They support an iterative development model. These approaches are characterized as follows: Test-Driven Development (TDD): Directs the coding through test cases (instead of extensive software design) (Beck 2003) Tests are written first, then the code is written to satisfy the tests, and then the tests and code are refactored Acceptance Test-Driven Development (ATDD) (see section 4.5.3): Derives tests from acceptance criteria as part of the system design process (Gärtner 2011) Tests are written before the part of the application is developed to satisfy the tests Behavior-Driven Development (BDD): Expresses the desired behavior of an application with test cases written in a simple form of natural language, which is easy to understand by stakeholders – usually using the Given/When/Then format. (Chelimsky 2010) Test cases are then automatically translated into executable tests For all the above approaches, tests may persist as automated tests to ensure the code quality in future adaptions / refactoring. 2.1.4. DevOps and Testing DevOps is an organizational approach aiming to create synergy by getting development (including testing) and operations to work together to achieve a set of common goals. DevOps requires a cultural shift within an organization to bridge the gaps between development (including testing) and operations while treating their functions with equal value. DevOps promotes team autonomy, fast feedback, integrated toolchains, and technical practices like continuous integration (CI) and continuous delivery (CD). This enables the teams to build, test and release high-quality code faster through a DevOps delivery pipeline (Kim 2016). From the testing perspective, some of the benefits of DevOps are: Fast feedback on the code quality, and whether changes adversely affect existing code CI promotes a shift-left approach in testing (see section 2.1.5) by encouraging developers to submit high quality code accompanied by component tests and static analysis Promotes automated processes like CI/CD that facilitate establishing stable test environments Increases the view on non-functional quality characteristics (e.g., performance, reliability) v4.0 Page 25 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Automation through a delivery pipeline reduces the need for repetitive manual testing The risk in regression is minimized due to the scale and range of automated regression tests DevOps is not without its risks and challenges, which include: The DevOps delivery pipeline must be defined and established CI / CD tools must be introduced and maintained Test automation requires additional resources and may be difficult to establish and maintain Although DevOps comes with a high level of automated testing, manual testing – especially from the user's perspective – will still be needed. 2.1.5. Shift-Left Approach The principle of early testing (see section 1.3) is sometimes referred to as shift-left because it is an approach where testing is performed earlier in the SDLC. Shift-left normally suggests that testing should be done earlier (e.g., not waiting for code to be implemented or for components to be integrated), but it does not mean that testing later in the SDLC should be neglected. There are some good practices that illustrate how to achieve a “shift-left” in testing, which include: Reviewing the specification from the perspective of testing. These review activities on specifications often find potential defects, such as ambiguities, incompleteness, and inconsistencies Writing test cases before the code is written and have the code run in a test harness during code implementation Using CI and even better CD as it comes with fast feedback and automated component tests to accompany source code when it is submitted to the code repository Completing static analysis of source code prior to dynamic testing, or as part of an automated process Performing non-functional testing starting at the component test level, where possible. This is a form of shift-left as these non-functional test types tend to be performed later in the SDLC when a complete system and a representative test environment are available A shift-left approach might result in extra training, effort and/or costs earlier in the process but is expected to save efforts and/or costs later in the process. For the shift-left approach it is important that stakeholders are convinced and bought into this concept. 2.1.6. Retrospectives and Process Improvement Retrospectives (also known as “post-project meetings” and project retrospectives) are often held at the end of a project or an iteration, at a release milestone, or can be held when needed. The timing and organization of the retrospectives depend on the particular SDLC model being followed. In these meetings the participants (not only testers, but also e.g., developers, architects, product owner, business analysts) discuss: What was successful, and should be retained? v4.0 Page 26 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level What was not successful and could be improved? How to incorporate the improvements and retain the successes in the future? The results should be recorded and are normally part of the test completion report (see section 5.3.2). Retrospectives are critical for the successful implementation of continuous improvement and it is important that any recommended improvements are followed up. Typical benefits for testing include: Increased test effectiveness / efficiency (e.g., by implementing suggestions for process improvement) Increased quality of testware (e.g., by jointly reviewing the test processes) Team bonding and learning (e.g., as a result of the opportunity to raise issues and propose improvement points) Improved quality of the test basis (e.g., as deficiencies in the extent and quality of the requirements could be addressed and solved) Better cooperation between development and testing (e.g., as collaboration is reviewed and optimized regularly) 2.2. Test Levels and Test Types Test levels are groups of test activities that are organized and managed together. Each test level is an instance of the test process, performed in relation to software at a given stage of development, from individual components to complete systems or, where applicable, systems of systems. Test levels are related to other activities within the SDLC. In sequential SDLC models, the test levels are often defined such that the exit criteria of one level are part of the entry criteria for the next level. In some iterative models, this may not apply. Development activities may span through multiple test levels. Test levels may overlap in time. Test types are groups of test activities related to specific quality characteristics and most of those test activities can be performed at every test level. 2.2.1. Test Levels In this syllabus, the following five test levels are described: Component testing (also known as unit testing) focuses on testing components in isolation. It often requires specific support, such as test harnesses or unit test frameworks. Component testing is normally performed by developers in their development environments. Component integration testing (also known as unit integration testing) focuses on testing the interfaces and interactions between components. Component integration testing is heavily dependent on the integration strategy approaches like bottom-up, top-down or big-bang. System testing focuses on the overall behavior and capabilities of an entire system or product, often including functional testing of end-to-end tasks and the non-functional testing of quality characteristics. For some non-functional quality characteristics, it is preferable to test them on a complete system in a representative test environment (e.g., usability). Using simulations of sub- v4.0 Page 27 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level systems is also possible. System testing may be performed by an independent test team, and is related to specifications for the system. System integration testing focuses on testing the interfaces of the system under test and other systems and external services. System integration testing requires suitable test environments preferably similar to the operational environment. Acceptance testing focuses on validation and on demonstrating readiness for deployment, which means that the system fulfills the user’s business needs. Ideally, acceptance testing should be performed by the intended users. The main forms of acceptance testing are: user acceptance testing (UAT), operational acceptance testing, contractual and regulatory acceptance testing, alpha testing and beta testing. Test levels are distinguished by the following non-exhaustive list of attributes, to avoid overlapping of test activities: Test object Test objectives Test basis Defects and failures Approach and responsibilities 2.2.2. Test Types A lot of test types exist and can be applied in projects. In this syllabus, the following four test types are addressed: Functional testing evaluates the functions that a component or system should perform. The functions are “what” the test object should do. The main objective of functional testing is checking the functional completeness, functional correctness and functional appropriateness. Non-functional testing evaluates attributes other than functional characteristics of a component or system. Non-functional testing is the testing of “how well the system behaves”. The main objective of non- functional testing is checking the non-functional software quality characteristics. The ISO/IEC 25010 standard provides the following classification of the non-functional software quality characteristics: Performance efficiency Compatibility Usability Reliability Security Maintainability Portability It is sometimes appropriate for non-functional testing to start early in the life cycle (e.g., as part of reviews and component testing or system testing). Many non-functional tests are derived from functional tests as v4.0 Page 28 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level they use the same functional tests, but check that while performing the function, a non-functional constraint is satisfied (e.g., checking that a function performs within a specified time, or a function can be ported to a new platform). The late discovery of non-functional defects can pose a serious threat to the success of a project. Non-functional testing sometimes needs a very specific test environment, such as a usability lab for usability testing. Black-box testing (see section 4.2) is specification-based and derives tests from documentation external to the test object. The main objective of black-box testing is checking the system's behavior against its specifications. White-box testing (see section 4.3) is structure-based and derives tests from the system's implementation or internal structure (e.g., code, architecture, work flows, and data flows). The main objective of white-box testing is to cover the underlying structure by the tests to the acceptable level. All the four above mentioned test types can be applied to all test levels, although the focus will be different at each level. Different test techniques can be used to derive test conditions and test cases for all the mentioned test types. 2.2.3. Confirmation Testing and Regression Testing Changes are typically made to a component or system to either enhance it by adding a new feature or to fix it by removing a defect. Testing should then also include confirmation testing and regression testing. Confirmation testing confirms that an original defect has been successfully fixed. Depending on the risk, one can test the fixed version of the software in several ways, including: executing all test cases that previously have failed due to the defect, or, also by adding new tests to cover any changes that were needed to fix the defect However, when time or money is short when fixing defects, confirmation testing might be restricted to simply exercising the steps that should reproduce the failure caused by the defect and checking that the failure does not occur. Regression testing confirms that no adverse consequences have been caused by a change, including a fix that has already been confirmation tested. These adverse consequences could affect the same component where the change was made, other components in the same system, or even other connected systems. Regression testing may not be restricted to the test object itself but can also be related to the environment. It is advisable first to perform an impact analysis to optimize the extent of the regression testing. Impact analysis shows which parts of the software could be affected. Regression test suites are run many times and generally the number of regression test cases will increase with each iteration or release, so regression testing is a strong candidate for automation. Automation of these tests should start early in the project. Where CI is used, such as in DevOps (see section 2.1.4), it is good practice to also include automated regression tests. Depending on the situation, this may include regression tests on different levels. Confirmation testing and/or regression testing for the test object are needed on all test levels if defects are fixed and/or changes are made on these test levels. v4.0 Page 29 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 2.3. Maintenance Testing There are different categories of maintenance, it can be corrective, adaptive to changes in the environment or improve performance or maintainability (see ISO/IEC 14764 for details), so maintenance can involve planned releases/deployments and unplanned releases/deployments (hot fixes). Impact analysis may be done before a change is made, to help decide if the change should be made, based on the potential consequences in other areas of the system. Testing the changes to a system in production includes both evaluating the success of the implementation of the change and the checking for possible regressions in parts of the system that remain unchanged (which is usually most of the system). The scope of maintenance testing typically depends on: The degree of risk of the change The size of the existing system The size of the change The triggers for maintenance and maintenance testing can be classified as follows: Modifications, such as planned enhancements (i.e., release-based), corrective changes or hot fixes. Upgrades or migrations of the operational environment, such as from one platform to another, which can require tests associated with the new environment as well as of the changed software, or tests of data conversion when data from another application is migrated into the system being maintained. Retirement, such as when an application reaches the end of its life. When a system is retired, this can require testing of data archiving if long data-retention periods are required. Testing of restore and retrieval procedures after archiving may also be needed in the event that certain data is required during the archiving period. v4.0 Page 30 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 3. Static Testing – 80 minutes Keywords anomaly, dynamic testing, formal review, informal review, inspection, review, static analysis, static testing, technical review, walkthrough Learning Objectives for Chapter 3: 3.1 Static Testing Basics FL-3.1.1 (K1) Recognize types of products that can be examined by the different static test techniques FL-3.1.2 (K2) Explain the value of static testing FL-3.1.3 (K2) Compare and contrast static and dynamic testing 3.2 Feedback and Review Process FL-3.2.1 (K1) Identify the benefits of early and frequent stakeholder feedback FL-3.2.2 (K2) Summarize the activities of the review process FL-3.2.3 (K1) Recall which responsibilities are assigned to the principal roles when performing reviews FL-3.2.4 (K2) Compare and contrast the different review types FL-3.2.5 (K1) Recall the factors that contribute to a successful review v4.0 Page 31 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 3.1. Static Testing Basics In contrast to dynamic testing, in static testing the software under test does not need to be executed. Code, process specification, system architecture specification or other work products are evaluated through manual examination (e.g., reviews) or with the help of a tool (e.g., static analysis). Test objectives include improving quality, detecting defects and assessing characteristics like readability, completeness, correctness, testability and consistency. Static testing can be applied for both verification and validation. Testers, business representatives and developers work together during example mappings, collaborative user story writing and backlog refinement sessions to ensure that user stories and related work products meet defined criteria, e.g., the Definition of Ready (see section 5.1.3). Review techniques can be applied to ensure user stories are complete and understandable and include testable acceptance criteria. By asking the right questions, testers explore, challenge and help improve the proposed user stories. Static analysis can identify problems prior to dynamic testing while often requiring less effort, since no test cases are required, and tools (see chapter 6) are typically used. Static analysis is often incorporated into CI frameworks (see section 2.1.4). While largely used to detect specific code defects, static analysis is also used to evaluate maintainability and security. Spelling checkers and readability tools are other examples of static analysis tools. 3.1.1. Work Products Examinable by Static Testing Almost any work product can be examined using static testing. Examples include requirement specification documents, source code, test plans, test cases, product backlog items, test charters, project documentation, contracts and models. Any work product that can be read and understood can be the subject of a review. However, for static analysis, work products need a structure against which they can be checked (e.g., models, code or text with a formal syntax). Work products that are not appropriate for static testing include those that are difficult to interpret by human beings and that should not be analyzed by tools (e.g., 3rd party executable code due to legal reasons). 3.1.2. Value of Static Testing Static testing can detect defects in the earliest phases of the SDLC, fulfilling the principle of early testing (see section 1.3). It can also identify defects which cannot be detected by dynamic testing (e.g., unreachable code, design patterns not implemented as desired, defects in non-executable work products). Static testing provides the ability to evaluate the quality of, and to build confidence in work products. By verifying the documented requirements, the stakeholders can also make sure that these requirements describe their actual needs. Since static testing can be performed early in the SDLC, a shared understanding can be created among the involved stakeholders. Communication will also be improved between the involved stakeholders. For this reason, it is recommended to involve a wide variety of stakeholders in static testing. Even though reviews can be costly to implement, the overall project costs are usually much lower than when no reviews are performed because less time and effort needs to be spent on fixing defects later in the project. v4.0 Page 32 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Code defects can be detected using static analysis more efficiently than in dynamic testing, usually resulting in both fewer code defects and a lower overall development effort. 3.1.3. Differences between Static Testing and Dynamic Testing Static testing and dynamic testing practices complement each other. They have similar objectives, such as supporting the detection of defects in work products (see section 1.1.1), but there are also some differences, such as: Static and dynamic testing (with analysis of failures) can both lead to the detection of defects, however there are some defect types that can only be found by either static or dynamic testing. Static testing finds defects directly, while dynamic testing causes failures from which the associated defects are determined through subsequent analysis Static testing may more easily detect defects that lay on paths through the code that are rarely executed or hard to reach using dynamic testing Static testing can be applied to non-executable work products, while dynamic testing can only be applied to executable work products Static testing can be used to measure quality characteristics that are not dependent on executing code (e.g., maintainability), while dynamic testing can be used to measure quality characteristics that are dependent on executing code (e.g., performance efficiency) Typical defects that are easier and/or cheaper to find through static testing include: Defects in requirements (e.g., inconsistencies, ambiguities, contradictions, omissions, inaccuracies, duplications) Design defects (e.g., inefficient database structures, poor modularization) Certain types of coding defects (e.g., variables with undefined values, undeclared variables, unreachable or duplicated code, excessive code complexity) Deviations from standards (e.g., lack of adherence to naming conventions in coding standards) Incorrect interface specifications (e.g., mismatched number, type or order of parameters) Specific types of security vulnerabilities (e.g., buffer overflows) Gaps or inaccuracies in test basis coverage (e.g., missing tests for an acceptance criterion) 3.2. Feedback and Review Process 3.2.1. Benefits of Early and Frequent Stakeholder Feedback Early and frequent feedback allows for the early communication of potential quality problems. If there is little stakeholder involvement during the SDLC, the product being developed might not meet the stakeholder’s original or current vision. A failure to deliver what the stakeholder wants can result in costly rework, missed deadlines, blame games, and might even lead to complete project failure. v4.0 Page 33 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Frequent stakeholder feedback throughout the SDLC can prevent misunderstandings about requirements and ensure that changes to requirements are understood and implemented earlier. This helps the development team to improve their understanding of what they are building. It allows them to focus on those features that deliver the most value to the stakeholders and that have the most positive impact on identified risks. 3.2.2. Review Process Activities The ISO/IEC 20246 standard defines a generic review process that provides a structured but flexible framework from which a specific review process may be tailored to a particular situation. If the required review is more formal, then more of the tasks described for the different activities will be needed. The size of many work products makes them too large to be covered by a single review. The review process may be invoked a couple of times to complete the review for the entire work product. The activities in the review process are: Planning. During the planning phase, the scope of the review, which comprises the purpose, the work product to be reviewed, quality characteristics to be evaluated, areas to focus on, exit criteria, supporting information such as standards, effort and the timeframes for the review, shall be defined. Review initiation. During review initiation, the goal is to make sure that everyone and everything involved is prepared to start the review. This includes making sure that every participant has access to the work product under review, understands their role and responsibilities and receives everything needed to perform the review. Individual review. Every reviewer performs an individual review to assess the quality of the work product under review, and to identify anomalies, recommendations, and questions by applying one or more review techniques (e.g., checklist-based reviewing, scenario-based reviewing). The ISO/IEC 20246 standard provides more depth on different review techniques. The reviewers log all their identified anomalies, recommendations, and questions. Communication and analysis. Since the anomalies identified during a review are not necessarily defects, all these anomalies need to be analyzed and discussed. For every anomaly, the decision should be made on its status, ownership and required actions. This is typically done in a review meeting, during which the participants also decide what the quality level of reviewed work product is and what follow-up actions are required. A follow-up review may be required to complete actions. Fixing and reporting. For every defect, a defect report should be created so that corrective actions can be followed-up. Once the exit criteria are reached, the work product can be accepted. The review results are reported. 3.2.3. Roles and Responsibilities in Reviews Reviews involve various stakeholders, who may take on several roles. The principal roles and their responsibilities are: Manager – decides what is to be reviewed and provides resources, such as staff and time for the review Author – creates and fixes the work product under review v4.0 Page 34 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Moderator (also known as the facilitator) – ensures the effective running of review meetings, including mediation, time management, and a safe review environment in which everyone can speak freely Scribe (also known as recorder) – collates anomalies from reviewers and records review information, such as decisions and new anomalies found during the review meeting Reviewer – performs reviews. A reviewer may be someone working on the project, a subject matter expert, or any other stakeholder Review leader – takes overall responsibility for the review such as deciding who will be involved, and organizing when and where the review will take place Other, more detailed roles are possible, as described in the ISO/IEC 20246 standard. 3.2.4. Review Types There exist many review types ranging from informal reviews to formal reviews. The required level of formality depends on factors such as the SDLC being followed, the maturity of the development process, the criticality and complexity of the work product being reviewed, legal or regulatory requirements, and the need for an audit trail. The same work product can be reviewed with different review types, e.g., first an informal one and later a more formal one. Selecting the right review type is key to achieving the required review objectives (see section 3.2.5). The selection is not only based on the objectives, but also on factors such as the project needs, available resources, work product type and risks, business domain, and company culture. Some commonly used review types are: Informal review. Informal reviews do not follow a defined process and do not require a formal documented output. The main objective is detecting anomalies. Walkthrough. A walkthrough, which is led by the author, can serve many objectives, such as evaluating quality and building confidence in the work product, educating reviewers, gaining consensus, generating new ideas, motivating and enabling authors to improve and detecting anomalies. Reviewers might perform an individual review before the walkthrough, but this is not required. Technical Review. A technical review is performed by technically qualified reviewers and led by a moderator. The objectives of a technical review are to gain consensus and make decisions regarding a technical problem, but also to detect anomalies, evaluate quality and build confidence in the work product, generate new ideas, and to motivate and enable authors to improve. Inspection. As inspections are the most formal type of review, they follow the complete generic process (see section 3.2.2). The main objective is to find the maximum number of anomalies. Other objectives are to evaluate quality, build confidence in the work product, and to motivate and enable authors to improve. Metrics are collected and used to improve the SDLC, including the inspection process. In inspections, the author cannot act as the review leader or scribe. 3.2.5. Success Factors for Reviews There are several factors that determine the success of reviews, which include: v4.0 Page 35 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Defining clear objectives and measurable exit criteria. Evaluation of participants should never be an objective Choosing the appropriate review type to achieve the given objectives, and to suit the type of work product, the review participants, the project needs and context Conducting reviews on small chunks, so that reviewers do not lose concentration during an individual review and/or the review meeting (when held) Providing feedback from reviews to stakeholders and authors so they can improve the product and their activities (see section 3.2.1) Providing adequate time to participants to prepare for the review Support from management for the review process Making reviews part of the organization’s culture, to promote learning and process improvement Providing adequate training for all participants so they know how to fulfil their role Facilitating meetings v4.0 Page 36 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 4. Test Analysis and Design – 390 minutes Keywords acceptance criteria, acceptance test-driven development, black-box test technique, boundary value analysis, branch coverage, checklist-based testing, collaboration-based test approach, coverage, coverage item, decision table testing, equivalence partitioning, error guessing, experience-based test technique, exploratory testing, state transition testing, statement coverage, test technique, white-box test technique Learning Objectives for Chapter 4: 4.1 Test Techniques Overview FL-4.1.1 (K2) Distinguish black-box, white-box and experience-based test techniques 4.2 Black-box Test Techniques FL-4.2.1 (K3) Use equivalence partitioning to derive test cases FL-4.2.2 (K3) Use boundary value analysis to derive test cases FL-4.2.3 (K3) Use decision table testing to derive test cases FL-4.2.4 (K3) Use state transition testing to derive test cases 4.3 White-box Test Techniques FL-4.3.1 (K2) Explain statement testing FL-4.3.2 (K2) Explain branch testing FL-4.3.3 (K2) Explain the value of white-box testing 4.4 Experience-based Test Techniques FL-4.4.1 (K2) Explain error guessing FL-4.4.2 (K2) Explain exploratory testing FL-4.4.3 (K2) Explain checklist-based testing 4.5. Collaboration-based Test Approaches FL-4.5.1 (K2) Explain how to write user stories in collaboration with developers and business representatives FL-4.5.2 (K2) Classify the different options for writing acceptance criteria FL-4.5.3 (K3) Use acceptance test-driven development (ATDD) to derive test cases v4.0 Page 37 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 4.1. Test Techniques Overview Test techniques support the tester in test analysis (what to test) and in test design (how to test). Test techniques help to develop a relatively small, but sufficient, set of test cases in a systematic way. Test techniques also help the tester to define test conditions, identify coverage items, and identify test data during the test analysis and design. Further information on test techniques and their corresponding measures can be found in the ISO/IEC/IEEE 29119-4 standard, and in (Beizer 1990, Craig 2002, Copeland 2004, Koomen 2006, Jorgensen 2014, Ammann 2016, Forgács 2019). In this syllabus, test techniques are classified as black-box, white-box, and experience-based. Black-box test techniques (also known as specification-based techniques) are based on an analysis of the specified behavior of the test object without reference to its internal structure. Therefore, the test cases are independent of how the software is implemented. Consequently, if the implementation changes, but the required behavior stays the same, then the test cases are still useful. White-box test techniques (also known as structure-based techniques) are based on an analysis of the test object’s internal structure and processing. As the test cases are dependent on how the software is designed, they can only be created after the design or implementation of the test object. Experience-based test techniques effectively use the knowledge and experience of testers for the design and implementation of test cases. The effectiveness of these techniques depends heavily on the tester’s skills. Experience-based test techniques can detect defects that may be missed using the black- box and white-box test techniques. Hence, experience-based test techniques are complementary to the black-box and white-box test techniques. 4.2. Black-Box Test Techniques Commonly used black-box test techniques discussed in the following sections are: Equivalence Partitioning Boundary Value Analysis Decision Table Testing State Transition Testing 4.2.1. Equivalence Partitioning Equivalence Partitioning (EP) divides data into partitions (known as equivalence partitions) based on the expectation that all the elements of a given partition are to be processed in the same way by the test object. The theory behind this technique is that if a test case, that tests one value from an equivalence partition, detects a defect, this defect should also be detected by test cases that test any other value from the same partition. Therefore, one test for each partition is sufficient. Equivalence partitions can be identified for any data element related to the test object, including inputs, outputs, configuration items, internal values, time-related values, and interface parameters. The partitions may be continuous or discrete, ordered or unordered, finite or infinite. The partitions must not overlap and must be non-empty sets. For simple test objects EP can be easy, but in practice, understanding how the test object will treat different values is often complicated. Therefore, partitioning should be done with care. v4.0 Page 38 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level A partition containing valid values is called a valid partition. A partition containing invalid values is called an invalid partition. The definitions of valid and invalid values may vary among teams and organizations. For example, valid values may be interpreted as those that should be processed by the test object or as those for which the specification defines their processing. Invalid values may be interpreted as those that should be ignored or rejected by the test object or as those for which no processing is defined in the test object specification. In EP, the coverage items are the equivalence partitions. To achieve 100% coverage with this technique, test cases must exercise all identified partitions (including invalid partitions) by covering each partition at least once. Coverage is measured as the number of partitions exercised by at least one test case, divided by the total number of identified partitions, and is expressed as a percentage. Many test objects include multiple sets of partitions (e.g., test objects with more than one input parameter), which means that a test case will cover partitions from different sets of partitions. The simplest coverage criterion in the case of multiple sets of partitions is called Each Choice coverage (Ammann 2016). Each Choice coverage requires test cases to exercise each partition from each set of partitions at least once. Each Choice coverage does not take into account combinations of partitions. 4.2.2. Boundary Value Analysis Boundary Value Analysis (BVA) is a technique based on exercising the boundaries of equivalence partitions. Therefore, BVA can only be used for ordered partitions. The minimum and maximum values of a partition are its boundary values. In the case of BVA, if two elements belong to the same partition, all elements between them must also belong to that partition. BVA focuses on the boundary values of the partitions because developers are more likely to make errors with these boundary values. Typical defects found by BVA are located where implemented boundaries are misplaced to positions above or below their intended positions or are omitted altogether. This syllabus covers two versions of the BVA: 2-value and 3-value BVA. They differ in terms of coverage items per boundary that need to be exercised to achieve 100% coverage. In 2-value BVA (Craig 2002, Myers 2011), for each boundary value there are two coverage items: this boundary value and its closest neighbor belonging to the adjacent partition. To achieve 100% coverage with 2-value BVA, test cases must exercise all coverage items, i.e., all identified boundary values. Coverage is measured as the number of boundary values that were exercised, divided by the total number of identified boundary values, and is expressed as a percentage. In 3-value BVA (Koomen 2006, O’Regan 2019), for each boundary value there are three coverage items: this boundary value and both its neighbors. Therefore, in 3-value BVA some of the coverage items may not be boundary values. To achieve 100% coverage with 3-value BVA, test cases must exercise all coverage items, i.e., identified boundary values and their neighbors. Coverage is measured as the number of boundary values and their neighbors exercised, divided by the total number of identified boundary values and their neighbors, and is expressed as a percentage. 3-value BVA is more rigorous than 2-value BVA as it may detect defects overlooked by 2-value BVA. For example, if the decision “if (x ≤ 10) …” is incorrectly implemented as “if (x = 10) …”, no test data derived from the 2-value BVA (x = 10, x = 11) can detect the defect. However, x = 9, derived from the 3-value BVA, is likely to detect it. v4.0 Page 39 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 4.2.3. Decision Table Testing Decision tables are used for testing the implementation of system requirements that specify how different combinations of conditions result in different outcomes. Decision tables are an effective way of recording complex logic, such as business rules. When creating decision tables, the conditions and the resulting actions of the system are defined. These form the rows of the table. Each column corresponds to a decision rule that defines a unique combination of conditions, along with the associated actions. In limited-entry decision tables all the values of the conditions and actions (except for irrelevant or infeasible ones; see below) are shown as Boolean values (true or false). Alternatively, in extended-entry decision tables some or all the conditions and actions may also take on multiple values (e.g., ranges of numbers, equivalence partitions, discrete values). The notation for conditions is as follows: “T” (true) means that the condition is satisfied. “F” (false) means that the condition is not satisfied. “–” means that the value of the condition is irrelevant for the action outcome. “N/A” means that the condition is infeasible for a given rule. For actions: “X” means that the action should occur. Blank means that the action should not occur. Other notations may also be used. A full decision table has enough columns to cover every combination of conditions. The table can be simplified by deleting columns containing infeasible combinations of conditions. The table can also be minimized by merging columns, in which some conditions do not affect the outcome, into a single column. Decision table minimization algorithms are out of scope of this syllabus. In decision table testing, the coverage items are the columns containing feasible combinations of conditions. To achieve 100% coverage with this technique, test cases must exercise all these columns. Coverage is measured as the number of exercised columns, divided by the total number of feasible columns, and is expressed as a percentage. The strength of decision table testing is that it provides a systematic approach to identify all the combinations of conditions, some of which might otherwise be overlooked. It also helps to find any gaps or contradictions in the requirements. If there are many conditions, exercising all the decision rules may be time consuming, since the number of rules grows exponentially with the number of conditions. In such a case, to reduce the number of rules that need to be exercised, a minimized decision table or a risk- based approach may be used. 4.2.4. State Transition Testing A state transition diagram models the behavior of a system by showing its possible states and valid state transitions. A transition is initiated by an event, which may be additionally qualified by a guard condition. The transitions are assumed to be instantaneous and may sometimes result in the software taking action. The common transition labeling syntax is as follows: “event [guard condition] / action”. Guard conditions and actions can be omitted if they do not exist or are irrelevant for the tester. A state table is a model equivalent to a state transition diagram. Its rows represent states, and its columns represent events (together with guard conditions if they exist). Table entries (cells) represent transitions, and contain the target state, as well as the resulting actions, if defined. In contrast to the state transition diagram, the state table explicitly shows invalid transitions, which are represented by empty cells. A test case based on a state transition diagram or state table is usually represented as a sequence of events, which results in a sequence of state changes (and actions, if needed). One test case may, and usually will, cover several transitions between states. There exist many coverage criteria for state transition testing. This syllabus discusses three of them. v4.0 Page 40 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level In all states coverage, the coverage items are the states. To achieve 100% all states coverage, test cases must ensure that all the states are visited. Coverage is measured as the number of visited states divided by the total number of states, and is expressed as a percentage. In valid transitions coverage (also called 0-switch coverage), the coverage items are single valid transitions. To achieve 100% valid transitions coverage, test cases must exercise all the valid transitions. Coverage is measured as the number of exercised valid transitions divided by the total number of valid transitions, and is expressed as a percentage. In all transitions coverage, the coverage items are all the transitions shown in a state table. To achieve 100% all transitions coverage, test cases must exercise all the valid transitions and attempt to execute invalid transitions. Testing only one invalid transition in a single test case helps to avoid fault masking, i.e., a situation in which one defect prevents the detection of another. Coverage is measured as the number of valid and invalid transitions exercised or attempted to be covered by executed test cases, divided by the total number of valid and invalid transitions, and is expressed as a percentage. All states coverage is weaker than valid transitions coverage, because it can typically be achieved without exercising all the transitions. Valid transitions coverage is the most widely used coverage criterion. Achieving full valid transitions coverage guarantees full all states coverage. Achieving full all transitions coverage guarantees both full all states coverage and full valid transitions coverage and should be a minimum requirement for mission and safety-critical software. 4.3. White-Box Test Techniques Because of their popularity and simplicity, this section focuses on two code-related white-box test techniques: Statement testing Branch testing There are more rigorous techniques that are used in some safety-critical, mission-critical, or high-integrity environments to achieve more thorough code coverage. There are also white-box test techniques used in higher test levels (e.g., API testing), or using coverage not related to code (e.g., neuron coverage in neural network testing). These techniques are not discussed in this syllabus. 4.3.1. Statement Testing and Statement Coverage In statement testing, the coverage items are executable statements. The aim is to design test cases that exercise statements in the code until an acceptable level of coverage is achieved. Coverage is measured as the number of statements exercised by the test cases divided by the total number of executable statements in the code, and is expressed as a percentage. When 100% statement coverage is achieved, it ensures that all executable statements in the code have been exercised at least once. In particular, this means that each statement with a defect will be executed, which may cause a failure demonstrating the presence of the defect. However, exercising a statement with a test case will not detect defects in all cases. For example, it may not detect defects that are data dependent (e.g., a division by zero that only fails when a denominator is set to zero). Also, 100% statement coverage does not ensure that all the decision logic has been tested as, for instance, it may not exercise all the branches (see chapter 4.3.2) in the code. v4.0 Page 41 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level 4.3.2. Branch Testing and Branch Coverage A branch is a transfer of control between two nodes in the control flow graph, which shows the possible sequences in which source code statements are executed in the test object. Each transfer of control can be either unconditional (i.e., straight-line code) or conditional (i.e., a decision outcome). In branch testing the coverage items are branches and the aim is to design test cases to exercise branches in the code until an acceptable level of coverage is achieved. Coverage is measured as the number of branches exercised by the test cases divided by the total number of branches, and is expressed as a percentage. When 100% branch coverage is achieved, all branches in the code, unconditional and conditional, are exercised by test cases. Conditional branches typically correspond to a true or false outcome from an “if...then” decision, an outcome from a switch/case statement, or a decision to exit or continue in a loop. However, exercising a branch with a test case will not detect defects in all cases. For example, it may not detect defects requiring the execution of a specific path in a code. Branch coverage subsumes statement coverage. This means that any set of test cases achieving 100% branch coverage also achieves 100% statement coverage (but not vice versa). 4.3.3. The Value of White-box Testing A fundamental strength that all white-box techniques share is that the entire software implementation is taken into account during testing, which facilitates defect detection even when the software specification is vague, outdated or incomplete. A corresponding weakness is that if the software does not implement one or more requirements, white box testing may not detect the resulting defects of omission (Watson 1996). White-box techniques can be used in static testing (e.g., during dry runs of code). They are well suited to reviewing code that is not yet ready for execution (Hetzel 1988), as well as pseudocode and other high- level or top-down logic which can be modeled with a control flow graph. Performing only black-box testing does not provide a measure of actual code coverage. White-box coverage measures provide an objective measurement of coverage and provide the necessary information to allow additional tests to be generated to increase this coverage, and subsequently increase confidence in the code. 4.4. Experience-based Test Techniques Commonly used experience-based test techniques discussed in the following sections are: Error guessing Exploratory testing Checklist-based testing 4.4.1. Error Guessing Error guessing is a technique used to anticipate the occurrence of errors, defects, and failures, based on the tester’s knowledge, including: How the application has worked in the past v4.0 Page 42 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level The types of errors the developers tend to make and the types of defects that result from these errors The types of failures that have occurred in other, similar applications In general, errors, defects and failures may be related to: input (e.g., correct input not accepted, parameters wrong or missing), output (e.g., wrong format, wrong result), logic (e.g., missing cases, wrong operator), computation (e.g., incorrect operand, wrong computation), interfaces (e.g., parameter mismatch, incompatible types), or data (e.g., incorrect initialization, wrong type). Fault attacks are a methodical approach to the implementation of error guessing. This technique requires the tester to create or acquire a list of possible errors, defects and failures, and to design tests that will identify defects associated with the errors, expose the defects, or cause the failures. These lists can be built based on experience, defect and failure data, or from common knowledge about why software fails. See (Whittaker 2002, Whittaker 2003, Andrews 2006) for more information on error guessing and fault attacks. 4.4.2. Exploratory Testing In exploratory testing, tests are simultaneously designed, executed, and evaluated while the tester learns about the test object. The testing is used to learn more about the test object, to explore it more deeply with focused tests, and to create tests for untested areas. Exploratory testing is sometimes conducted using session-based testing to structure the testing. In a session-based approach, exploratory testing is conducted within a defined time-box. The tester uses a test charter containing test objectives to guide the testing. The test session is usually followed by a debriefing that involves a discussion between the tester and stakeholders interested in the test results of the test session. In this approach test objectives may be treated as high-level test conditions. Coverage items are identified and exercised during the test session. The tester may use test session sheets to document the steps followed and the discoveries made. Exploratory testing is useful when there are few or inadequate specifications or there is significant time pressure on the testing. Exploratory testing is also useful to complement other more formal test techniques. Exploratory testing will be more effective if the tester is experienced, has domain knowledge and has a high degree of essential skills, like analytical skills, curiosity and creativeness (see section 1.5.1). Exploratory testing can incorporate the use of other test techniques (e.g., equivalence partitioning). More information about exploratory testing can be found in (Kaner 1999, Whittaker 2009, Hendrickson 2013). 4.4.3. Checklist-Based Testing In checklist-based testing, a tester designs, implements, and executes tests to cover test conditions from a checklist. Checklists can be built based on experience, knowledge about what is important for the user, or an understanding of why and how software fails. Checklists should not contain items that can be checked automatically, items better suited as entry/exit criteria, or items that are too general (Brykczynski 1999). Checklist items are often phrased in the form of a question. It should be possible to check each item separately and directly. These items may refer to requirements, graphical interface properties, quality characteristics or other forms of test conditions. Checklists can be created to support various test types, including functional and non-functional testing (e.g., 10 heuristics for usability testing (Nielsen 1994)). v4.0 Page 43 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Some checklist entries may gradually become less effective over time because the developers will learn to avoid making the same errors. New entries may also need to be added to reflect newly found high severity defects. Therefore, checklists should be regularly updated based on defect analysis. However, care should be taken to avoid letting the checklist become too long (Gawande 2009). In the absence of detailed test cases, checklist-based testing can provide guidelines and some degree of consistency for the testing. If the checklists are high-level, some variability in the actual testing is likely to occur, resulting in potentially greater coverage but less repeatability. 4.5. Collaboration-based Test Approaches Each of the above-mentioned techniques (see sections 4.2, 4.3, 4.4) has a particular objective with respect to defect detection. Collaboration-based approaches, on the other hand, focus also on defect avoidance by collaboration and communication. 4.5.1. Collaborative User Story Writing A user story represents a feature that will be valuable to either a user or purchaser of a system or software. User stories have three critical aspects (Jeffries 2000), called together the “3 C’s”: Card – the medium describing a user story (e.g., an index card, an entry in an electronic board) Conversation – explains how the software will be used (can be documented or verbal) Confirmation – the acceptance criteria (see section 4.5.2) The most common format for a user story is “As a [role], I want [goal to be accomplished], so that I can [resulting business value for the role]”, followed by the acceptance criteria. Collaborative authorship of the user story can use techniques such as brainstorming and mind mapping. The collaboration allows the team to obtain a shared vision of what should be delivered, by taking into account three perspectives: business, development and testing. Good user stories should be: Independent, Negotiable, Valuable, Estimable, Small and Testable (INVEST). If a stakeholder does not know how to test a user story, this may indicate that the user story is not clear enough, or that it does not reflect something valuable to them, or that the stakeholder just needs help in testing (Wake 2003). 4.5.2. Acceptance Criteria Acceptance criteria for a user story are the conditions that an implementation of the user story must meet to be accepted by stakeholders. From this perspective, acceptance criteria may be viewed as the test conditions that should be exercised by the tests. Acceptance criteria are usually a result of the Conversation (see section 4.5.1). Acceptance criteria are used to: Define the scope of the user story Reach consensus among the stakeholders Describe both positive and negative scenarios Serve as a basis for the user story acceptance testing (see section 4.5.3) v4.0 Page 44 of 74 2023-04-21 © International Software Testing Qualifications Board Certified Tester Foundation Level Allow accurate planning and estimation There are several ways to write acceptance criteria for a user story. The two most common formats are: Scenario-oriented (e.g., Given/When/Then format used in BDD, see section 2.1.3) Rule-oriented (e.g., bullet point verification list, or tabulated form of input-output mapping) Most acceptance criteria can be documented in one of these two formats. However, the team may use another, custom format, as long as the acceptance criteria are well-defined and unambiguous. 4.5.3. Acceptance Test-driven Development (ATDD) ATDD is a test-first approach (see section 2.1.3). Test cases are created prior to implementing the user story. The test cases are created by team members with different perspectives, e.g., customers, developers, and testers (Adzic 2009). Test cases may be executed manually or automated. The first step is a specification workshop where the user story and (if not yet defined) its acceptance criteria are analyzed, discussed, and written by the team members. Incompleteness, ambiguities, or defects in the user story are resolved during this process. The next step is to create the test cases. This can be done by the team as a whole or by the tester individually. The test cases are based on the acceptance criteria and can be seen as examples of how the software works. This will help the team implement the user story correctly. Since examples and tests are the same, these terms are often used interchangeably. During the test design the test techniques described in sections 4.2, 4.3 and 4.4 may be applied. Typically, the first test cases are positive, confirming the correct behavior without exceptions or error conditions, and comprising the sequence of activities executed if everything goes as expected. After the positive test cases are done, the team should perform negative testing. Finally, the team should cover non-functional quality characteristics as well (e.g., performance efficiency, usability). Test cases should be expressed in a way that is understandable for the stakeholders. Typically, test cases contain sentences in natural language involving the necessary preconditions (if any), the inputs, and the postconditions. The test cases must cover all the characteristics of the user story and should not go beyond the story. However, the acceptance criteria may detail some of the issues described in the user story. In addition, no two test cases should describe the same characteristics of the user story. When captured in a format supported by a test automation framework, the developers can automate the test cases by writing the supporting code as they implement the feature des

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