Software Testing Fundamentals

Software Testing

• Testing demonstrates a program's functionality and identifies defects before use.
• Testing involves executing a program with artificial data.
• Results are checked for errors or anomalies in program attributes.
• Testing reveals the presence of errors, not their absence.
• This is part of the broader software verification and validation process.

Program Testing Goals

• Demonstrate software meets requirements to developers and customers.
• For custom software, each requirement should have a test case.
• For generic products, tests check features and combinations of features.
• Identify situations where software behavior is incorrect or doesn't meet specifications.
• Defect testing aims to discover undesirable behavior like crashes or data corruption.

Testing Process Goals

• Validation testing demonstrates that software meets requirements.
• A successful test shows the system meets specifications.
• Defect testing seeks faults where behavior is incorrect or doesn't meet specifications.
• A successful defect test reveals a system defect.

Validation and Defect Testing

• Validation testing ensures the system operates as intended, using test cases reflecting expected use.
• Defect testing uses test cases to expose defects, not relying on normal system usage.

Input-Output Model of Program Testing

• Validation testing uses correct inputs, focused on expected behavior.
• Defect testing locates inputs to reveal anomalous behavior.

Verification vs Validation

• Verification is determining if the product is built correctly.
• Validation is establishing if the right product is being built.
• Validation is more comprehensive, considering broader user needs, and not just conforming to specifications.

Inspections and Testing

• Software inspections analyze static representations to find problems.
• Static verification techniques don't require running the software.
• Inspections are effective at discovering program errors.
• Software testing is dynamic verification, executing the software for observable results.

Advantages of Inspections over Testing

• Inspections can find issues independently from other defects.
• Incomplete or early versions can be inspected at less cost.
• Inspections can check general quality requirements like style or standards.

Software Testing Process Model

• Development Testing: Developers test during development.
• Release Testing: Separate team tests before release to users.
• User Testing: Users or potential users test in their environment.

Development Testing

• Unit testing: Testing individual units (methods, objects) in isolation.
• Component testing: Integrates and tests components.
• System testing: Tests the integrated system.

Unit Testing

• A process for testing individual components.
• Isolation is a key characteristic.
• Units can be individual functions, methods, or objects.

Object Class Testing

• Complete test coverage for operations and attributes,
• Accounts for different states (simulating events to cause state change).
• Inheritance can complicate testing. Information to test may be in a different part of the objects.

Weather Station Object Interface

• The Interface has functions for reporting variables, controlling instruments, reconfiguration of the system.

Weather Station Testing

• Using a state model to identify state transition sequences.
• Defining and testing event sequences for these transitions.

Automated Testing

• Unit tests should be automated.
• Automation frameworks (e.g., JUnit) help create and run program tests.

Automated Test Components

• Test setup: Initializing the system with input and expected output.
• Test call: Calling the tested object/method.
• Test assertion: Comparing actual with expected results.
• Mock objects simulate external dependencies during testing.

Choosing Unit Test Cases

• Design tests to show expected behavior, and reveal defects.
• Two types of test cases: normal operation tests and abnormal tests.

Testing Strategies

• Partition Testing: Groups inputs into partitions based on similar outcomes.
• Guideline-based Testing: Choose test cases using past experience.

Equivalence Partitioning

• Divide input data into groups with equivalent behavior
• Select tests from the boundaries of the partitions.

Testing Guidelines (Sequences)

• Test cases should cover various situations, including different sizes of data, various sequences, start and end points.

General Testing Guidelines

• Inputs should cause error messages.
• Test for input buffer overflows.
• Test with repeated or various inputs.
• Check for result values that are too large, or too small.

Component Testing

• Testing composite components with interacting objects.
• Focusing on component interfaces and expected behavior.

Interface Testing

• Objectives: Detecting errors and invalid assumptions in interfaces.
• Interface testing examines communication between components.
• Types of interface errors include misuse, misunderstanding, and timeliness.

Interface Testing Guidelines

• Test parameters using extreme values.
• Test pointer parameters with null values.
• Stress test message-passing systems.
• Vary the order of activation in shared-memory systems

System Testing

• Integrating components and testing the integrated system, focusing on interactions amongst components.
• Testing involves verifying interaction between components.

Use-Case Testing

• Test scenarios derived to identify system interactions.
• Scenarios are stories of how a user interacts with the system.
• Use scenarios from requirements documents.

Collecting Weather Data Sequence Chart

• This is a flow-chart showing what events happen, and the order in these events.

Test Cases Derived from Sequence Diagram

• Sequence diagrams are sources for test cases.
• Test cases show expected input and output.
• Test raw data and results.

Testing Policies

• Exhaustive system testing isn't possible.
• Testing policies define necessary coverage.

Test-Driven Development (TDD)

• Test-first approach.
• Tests created before the code.
• Implementation is driven by test requirements.
• Benefits: Increased code coverage and easier debugging.

Regression Testing

• Ensures previous functionality is not broken by recent changes.
• Simple and automated in testing environments.
• Run tests whenever there is any code modification.

Release Testing

• System testing for a release intended for external use.
• Confirming the system meets requirements and is functional.
• Focuses on checking conformance with the specification, not just testing for defects.
• Important to involve team(s) that have not worked on the project.

Requirements Based Testing

• Ensures each system requirement is tested
• A method of validation testing
• Examines each requirement before designing tests.

Scenario Testing

• Using scenarios to help design test cases.
• Scenarios are realistic stories of how a user interacts with the system.
• Helps in identifying potential interactions amongst components.

Performance Testing

• Testing system response, stability, and reliability under different load levels.
• Crucial for systems with high user interaction.
• Methods like stress testing and operational profile testing.

Performance Testing - Operational Profile

• Reflects actual system workload
• Tests performance under expected conditions.

Performance Testing - Stress Test

• Overloads the system until it fails
• Allows understanding of failure behavior.
• Helps identify problems under heavy load conditions.

User Testing

• Users test or evaluate system from end-user point of view, using system as intended, in real environment settings.
• Essential for complete system assessment, not just for testing.

Types of User Testing

• Alpha testing, developers test internally.
• Beta testing, users provide feedback outside the company.
• Acceptance testing, decision point at a defined criteria point, not testing for bugs but accepting the system.

The Acceptance Testing Process

• Outlines the stages.
• Defines acceptance criteria based on functional specifications.
• Plans acceptance testing.
• Derives the required tests.
• Runs the tests and decides if the system is acceptable for deployment.

This quiz covers the essential concepts of software testing, including its goals, processes, and the importance of detecting defects. You will learn about testing methodologies and how they help validate that software meets specified requirements. Ideal for students and professionals looking to deepen their understanding of software quality assurance.