Software Testing Fundamentals
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Questions and Answers

What is a primary purpose of software testing?

  • To show the absence of errors.
  • To detect software failures. (correct)
  • To validate the cost of development.
  • To increase the complexity of the software.

What occurred during the launch of the Ariane 5 rocket?

  • The rocket launched without any issues.
  • The rocket was grounded for further testing.
  • The rocket reached its destination successfully.
  • The rocket self-destructed due to a software error. (correct)

What does testing validate about a software application?

  • It meets the business and technical requirements. (correct)
  • It guarantees user satisfaction.
  • It ensures the software is free from any bugs.
  • It provides a warranty against defects.

What can be a consequence of software malfunction in critical applications?

<p>Legal implications, such as charges of murder. (A)</p> Signup and view all the answers

Which type of number conversion caused the failure of the Ariane 5 rocket?

<p>Converting a floating point number to an integer. (C)</p> Signup and view all the answers

What is the main goal of a Module Test?

<p>To verify that the software modules meet the software specifications and design (D)</p> Signup and view all the answers

Which statement about testing is accurate?

<p>Testing is an ongoing process that helps identify defects. (C)</p> Signup and view all the answers

Which level of software testing focuses on integrating software modules into larger assemblies?

<p>Software Integration Test (A)</p> Signup and view all the answers

What does defect masking refer to in software testing?

<p>Modifying software to prevent errors from being showcased. (D)</p> Signup and view all the answers

What is the primary purpose of the Software Test phase?

<p>To provide confidence that the software meets business requirements (A)</p> Signup and view all the answers

What is a key limitation of testing in software development?

<p>It cannot demonstrate the complete absence of errors. (C)</p> Signup and view all the answers

Which of the following accurately describes the relationship between errors, faults, and failures?

<p>Errors are caused by faults, and faults lead to failures. (B)</p> Signup and view all the answers

What does 100% C1 coverage in Module Testing signify?

<p>All branches of code have been executed (A)</p> Signup and view all the answers

During which testing phase are the interactions between the interfaces of integrated modules tested?

<p>Integration Test (B)</p> Signup and view all the answers

Which statement best describes the focus of System Test?

<p>To uncover quality defects not previously detected (D)</p> Signup and view all the answers

What can be concluded from a failure occurring in the software?

<p>An error exists that may not be directly tied to the specifications (A)</p> Signup and view all the answers

What does software reliability refer to?

<p>Probability a software component will produce an incorrect output (A)</p> Signup and view all the answers

What was a significant oversight in the development of the Aegis radar system?

<p>User interface design considerations (B)</p> Signup and view all the answers

If two independent components A and B are critical for system operation, how is the probability of system failure calculated?

<p>P(S) = P(A) + P(B) (D)</p> Signup and view all the answers

What is the primary difference between testing and debugging?

<p>Testing uses predictable outcomes, while debugging does not. (B), Testing can be constrained in procedure, debugging cannot. (C)</p> Signup and view all the answers

What defines a 'fault' in the context of software programming?

<p>A structural imperfection in a software system (C)</p> Signup and view all the answers

What role do independent testers play in software development?

<p>They help to identify bugs that programmers may overlook. (D)</p> Signup and view all the answers

What is the consequence of software not wearing out?

<p>It does not necessarily guarantee correct output. (B)</p> Signup and view all the answers

What can be concluded about safety-critical software based on experiences in the industry?

<p>It can fail despite meeting project constraints. (C)</p> Signup and view all the answers

What is a common misconception about who tests programs?

<p>Programmers cannot test their own code well. (C)</p> Signup and view all the answers

When components in a system are replicated, what indicates the failure probability?

<p>P(S) = P(A) ^ n (B)</p> Signup and view all the answers

Why is testing often assigned to less experienced team members?

<p>Testing is perceived as a simplistic task for beginners. (B)</p> Signup and view all the answers

What does a test oracle do?

<p>It compares actual outputs to expected outputs for validation. (D)</p> Signup and view all the answers

What risk is associated with inadequate consideration of user behavior in system design?

<p>Potential for critical failures in real-world use (B)</p> Signup and view all the answers

What is often a limitation of testing a system?

<p>It cannot ensure absolute completeness in coverage. (D)</p> Signup and view all the answers

What does debugging require from a programmer that is different from testing?

<p>Intuitive leaps and freedom of thought. (C)</p> Signup and view all the answers

What is a consequence of the top-down testing approach, as illustrated by the Space Shuttle Columbia launch?

<p>Errors found cannot always be fixed without redesign costs. (C)</p> Signup and view all the answers

What does fault avoidance aim to achieve in a safety-related system?

<p>To avoid the introduction of faults (C)</p> Signup and view all the answers

What defines fault tolerance in a functional unit?

<p>Continuing to perform despite the presence of faults (C)</p> Signup and view all the answers

Which statement best describes an error in a system?

<p>A discrepancy that might lead to a failure (C)</p> Signup and view all the answers

What was the cause of the Ariane 5 rocket explosion?

<p>A software error due to improper data conversion (A)</p> Signup and view all the answers

Defect masking occurs when:

<p>A defect prevents another defect from being detected (B)</p> Signup and view all the answers

Which of the following best illustrates an example of defect masking?

<p>A user reports multiple issues, including one uninvestigated issue (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of fault tolerance?

<p>Automatic identification of errors (B)</p> Signup and view all the answers

Which data conversion caused the failure of the Ariane 5 rocket?

<p>Converting a 64-bit floating-point number to a 16-bit signed integer (C)</p> Signup and view all the answers

Which of the following is NOT a commonly used test oracle in automated class testing?

<p>A design pattern oracle (B)</p> Signup and view all the answers

What type of oracle evaluates results based on statistical characteristics?

<p>Statistical oracle (C)</p> Signup and view all the answers

In the context of automated class testing, what does the term "oracle" refer to?

<p>A mechanism to verify the correctness of test results (C)</p> Signup and view all the answers

Which of the following is NOT a challenge associated with using program-based oracles?

<p>Maintaining consistency across multiple test executions (D)</p> Signup and view all the answers

What type of oracle uses a second program to evaluate the same mathematical expression as the product under test?

<p>Other products oracle (C)</p> Signup and view all the answers

Which of the following is a method of automated oracle verification?

<p>Static code analysis (D)</p> Signup and view all the answers

What is the main purpose of a consistency oracle in automated class testing?

<p>To check if the output of the program under test is similar to the output of a previous execution (A)</p> Signup and view all the answers

What is the primary difference between a heuristic oracle and a statistical oracle?

<p>A heuristic oracle provides approximate results while a statistical oracle uses statistical characteristics. (B)</p> Signup and view all the answers

Flashcards

Software Testing

The process of validating and verifying a software product meets requirements and works as expected.

Defect Masking

When a software defect hides another defect, making it harder to detect the original issue.

Test Oracle

A mechanism or reference used to determine the expected result of a test case.

Failure, Fault, and Error

Failure is the occurrence of a defect, fault is the defect itself, and error refers to the mistake that caused the fault.

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ISO 9126

An international standard for evaluating software quality, focusing on attributes like functionality and reliability.

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Scope of Software Testing

Determines what features and aspects of the software will be tested during the testing process.

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Self-Destruct Mechanism

A safety feature that can destroy a system when a fault is detected to prevent harm or further failure.

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Ariane 5 Failure

A notable incident where a software error led to the destruction of the Ariane 5 rocket during its first launch.

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Module Test

A testing phase to verify that software modules meet specifications and design.

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Integration Test

A testing phase to ensure that integrated software modules work together as intended.

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Software Requirements

Specifications that define what the software should achieve and how it should behave.

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Software Test

Evaluation to confirm that software meets defined specifications and business requirements.

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System Test

A comprehensive testing phase assessing the system as a whole against requirements.

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System Integration Test

Testing the integration of different system components to ensure they work together.

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Failure

Occurs when the software's actual behavior diverges from expected behavior.

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Fault, Error, Failure

A fault causes an error, which can lead to a failure in software behavior.

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System reliability

The overall probability that a system will perform its intended function without failure.

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Hardware reliability

The probability that a hardware component fails during operation.

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Software reliability

The probability that a software component produces incorrect output during operation.

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Operator reliability

The probability that a system user will make an error while operating the system.

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Fault

An incorrect step or data definition in a program that leads to unintended behavior.

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Failure probability

The likelihood that a system will fail due to individual component failures.

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Shared system failure

Occurs when all replicated components in a system fail at once.

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User interface impact

The design of a system’s interface influences user errors and system failures.

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Fault Avoidance

Techniques to prevent faults in the safety lifecycle.

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Fault Tolerance

Ability to function correctly despite faults present.

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Error

Discrepancy between observed and true values or conditions.

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Ariane 5 Explosion

An incident caused by a software error leading to rocket failure.

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Defect Detection

The process of identifying software defects.

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Software Lifecycle

The phases a software product goes through from inception to retirement.

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Software Quality Assurance

Processes to ensure software meets quality standards.

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Debugging

The process of identifying and fixing errors or bugs in a program.

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Testing vs Debugging

Testing uses known conditions and has predictable outcomes, while debugging starts from unknowns and is unpredictable.

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Role of Programmers in Testing

Programmers often test their own code but might miss many bugs, necessitating independent testers.

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Difficulties of Testing

Testing is often viewed as a beginner's task and is sometimes done as an afterthought.

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Proof of Error

Testing serves as proof of a programmer's error or failure in the code.

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Importance of Different Testing Levels

Various levels of testing are essential to ensure thorough validation of software systems.

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Testing Intuition

Debugging requires intuitive leaps and freedom in exploring potential solutions.

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Method Postconditions

Conditions that must hold true after a method execution, used as automated oracles in testing.

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Heuristic Oracle

An oracle that provides approximate or exact results based on a limited set of test inputs.

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Statistical Oracle

Uses statistical characteristics to evaluate output, offering a probabilistic approach to results.

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Consistency Oracle

Compares results from different test executions for similarities and consistency.

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Model-based Oracle

Generates and verifies system behavior based on a predefined model.

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Testing Oracle

A program checking the output of another program to establish correctness.

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Input/Output Challenges

Complications in capturing and interpreting complex inputs and outputs during testing.

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Automated Oracles

Real-time mechanisms that verify program behavior against expected outcomes without human intervention.

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Study Notes

Introduction to Software Testing

  • Software testing is crucial to identify defects in software.
  • Failures of software can lead to significant consequences.
  • Testing aims to detect and fix defects before software is released.
  • The goal is to ensure software functions as expected
  • Comprehensive testing is necessary for a reliable, functional product.

Overview

  • Introduction
  • Purpose of testing
  • Software failures, faults, and errors
  • Defect masking
  • Testing and debugging
  • Industry standards (e.g., ISO 9126)
  • Software Reliability
  • Test oracle
  • Roles in testing (e.g., who tests?)

All in One Question

  • Example scenario: Leading a team to test a new X-ray machine software.
  • Would the job be accepted and under what conditions?
  • Impact of potential errors, highlighting the importance of software correctness.

Workflow: Scope of Software Testing

  • June 4, 1996 Ariane 5 rocket failure due to software error (data type conversion).
  • Demonstrates the critical nature of software testing.
  • Software failure can have catastrophic consequences.

Workflow: Levels of Testing

  • Module Test: Verifying the individual modules follow specifications.
  • Software Integration Test: Integration of different modules to form a complete unit.
  • Software Test: Evaluating if software fulfills specified requirements.
  • System Integration Test: Integration of hardware and software.
  • System Test: Final evaluation.

Workflow: Module Test

  • Purpose: Verify module correctness against specifications.
  • Target: 100% code coverage, 100% requirements coverage.
  • Distinction between testing and debugging: testing finds errors; debugging fixes them.

Workflow: Integration

  • Purpose: Integrate software modules into a cohesive whole.
  • Involves developers working together to combine modules, ensuring they function as intended.
  • Crucial phase for verifying interactions between modules.

Workflow: Integration Test

  • Purpose: Evaluate how software modules interact and communicate
  • Objectives: Detect failure in interaction, communication, resource management issues and runtime errors.

Workflow: Software Test

  • Purpose: Determine if the software meets all specifications.
  • Objective: Confirm the delivered software fulfills business requirements and user needs.
  • Crucial gateway for verifying the overall quality of the software.

Failure, Fault, Error

  • Failure: Observed behavior differs from the expected one.
  • Error: Part of a system that results in a failure.
  • Fault: Reason for an error (can be in software or hardware).

System Reliability

  • Hardware reliability: Likelihood of hardware component failure.
  • Software reliability: Likelihood of incorrect software output.
  • Operator reliability: Chance of user-introduced errors.

Failure, Fault, Error: Additional Notes

  • Well-tested software can still fail.
  • The Aegis radar system or the Vincennes shootdown highlight this.
  • System issues can stem from user needs not being met.

Failure Probability

  • Independent components: Failure probability is the sum of individual probabilities.
  • Replicated components: Failure probability is the individual component failure raised to the power of the number of components.

Failure, Fault, Error: Definition

  • Fault: An error in a computer program that causes unexpected behavior.
  • Inherent weakness in implementation or design might cause failure.
  • Methods and techniques for fault avoidance are important to ensure predictable results.
  • Fault tolerance is the ability of a functional unit to maintain function even in the presence of faults.

Failure, Fault, Error: Examples

  • Ariane 5 rocket failure: Example of a software error causing a catastrophic failure due to data type issues.

Defect Masking

  • Defect masking: A defect obscures or hides another defect.
  • Example of a defect in helping adding a new customer link.

Testing vs. Debugging

  • Testing: Determining if a program works correctly.
  • Debugging: Fixing problems in the program.
  • Key differences in approach and purpose.
  • Testing is performed by outsiders, whereas debugging is usually done by programmers.

Who Tests Programs?

  • Programmers frequently test their own code.
  • Independent testers are necessary for comprehensive quality assurance.

Difficulties of Testing

  • Testing often viewed as a low-priority task.
  • Limited testing resources for complex systems.
  • Difficulties in fully evaluating the behavior of a system.
  • Challenges in fixing errors once they're detected.
  • Difficulty with top-down testing because of fixes affecting entire systems.

Why Different Levels of Testing are Needed

  • Cost of correcting defects increases significantly as the process advances.
  • Early detection and correction of errors are cost-effective.
  • Early identification and correction in different levels help save resources.

Test Oracle

  • Test oracle: A mechanism for determining if a test has passed or failed.
  • Comparison of expected outputs to actual outputs.
  • Common types include specifications, other products, heuristic or statistical methods, or models for similarity.

Test Oracles: Additional Considerations

  • Oracles should accurately reflect the expected output to generate useful test results.
  • Capturing inputs and outputs may be challenging for complex interactions
  • Oracles need to handle complex I/O and parse to understand the actual output after a process.

Software Development Lifecycle: V Model

  • Key roles in each phase: System Analyst, System Architect, Software Analyst, Software Architect, Software Developer.
  • Essential documents at this phase: System Requirements Specification, Software Requirements Specification, Software Design.

Software Development Lifecycle: Important Documents

  • Key documents crucial for the V model lifecycle: Test plans, test reports, requirements, specifications, and design.

Software Quality (ISO 9126)

References

Exercise (MISRA Rules)

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Software Testing: Why Test Programs PDF

Description

This quiz covers essential concepts and principles of software testing, including the purposes, types, and processes involved in ensuring software quality. Test your knowledge on critical software testing phases such as Module Testing and System Testing, as well as historical examples like the Ariane 5 rocket launch failure.

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