Different Kinds of Test

Understanding Test Classifications

Overview of Testing Types

• The discussion begins with the importance of understanding various types of tests, noting that literature lacks consistency in test classifications.

• Different classifications can complement each other; they are not mutually exclusive and can be combined to better characterize a test.

Quality Factors in Testing

• The first classification relates to quality factors being verified by tests, primarily focusing on whether the system behaves as expected regarding quality aspects.

• Common quality factors include performance, security, usability, and robustness. Compatibility testing is also highlighted as an important aspect.

Programming Entities in Tests

• A second classification concerns the programming entities involved in testing—whether it targets a specific method or a broader service within the system.

• It’s essential to define which part of the code will be exercised during testing, ranging from high-level components to individual methods.

Handling Dependencies in Tests

• The third classification addresses how dependencies are managed during tests. This includes deciding whether to use older versions or stubs for unit testing.

• If newer versions of dependencies are used for integration testing, it indicates collaboration among developers working on different parts of the project.

Types of Testing Based on Dependency Management

• Unit tests focus on isolated classes without external dependencies; integration tests involve new versions created by other team members.

• System tests encompass all dependencies and simulate production environments, ensuring comprehensive end-to-end functionality is validated.

Understanding System Testing and Dependencies

The Importance of Testing in the Right Environment

• System tests must be conducted in an environment that mirrors production, including the correct versions of operating systems, browsers, and all necessary dependencies.

Class Dependency and Unit Testing

• A server class depends on a student list class; modifications to the server class require testing against both old and new versions of the student list.

• Unit tests can run with either the updated or previous version of the student list to ensure compatibility and functionality.

Simulating Behavior for Testing

• When a colleague's implementation is pending, stubs can simulate expected behavior for unit testing without needing the actual new version.

Integration Testing Context

• Integration tests assess how well different components work together after changes are made, particularly when new classes are introduced by team members.

Open World vs. Closed World Testing

• Unit testing operates in an "open world" where assumptions about surrounding code may not be fully known or available during testing.

• In contrast, integration testing allows for better understanding of interactions since properties of related code are known.

Types of Tests: Their Roles and Effectiveness

Comparison of Test Types Based on Dependencies

• Different types of tests (unit, integration, system) have varying effectiveness in detecting bugs based on their isolation from dependencies.

Bug Detection Capabilities

• Unit tests excel at isolating issues directly related to modified code; failures indicate specific problems within that code segment.

• Integration tests help locate bugs across multiple components but provide less certainty about which part caused a failure due to interdependencies.

Limitations of System Tests

• System tests offer minimal assistance in pinpointing defects because they evaluate entire systems with all dependencies; failures could arise from any component involved.

Understanding Guarantees Provided by Each Test Type

• While system tests demonstrate runtime issues effectively, they do not aid significantly in identifying root causes behind observed failures.

Stakeholder Expectations and Behavior Assurance

Understanding Testing Types in Software Development

The Role of Unit and Integration Tests

• There may be issues with unit tests that do not escalate into larger problems observable by users. Integration tests provide a medium level of assurance regarding the impact of these problems on users.

• Unit tests have low coverage as they only test a small part of the system, while system tests offer much greater coverage by involving multiple parts of the system.

• The feedback loop for performance is crucial; unit tests are quick to execute, whereas system tests can be very slow due to their complexity and involvement of various components.

• Some tests exhibit non-deterministic behavior, where they may pass once but fail upon re-execution. This issue is more prevalent in system tests than in unit or integration tests.

• Non-determinism can arise from external dependencies like web services. Unit and integration tests can mitigate this through mocking techniques.

Test Classifications: Open vs Closed Systems

• Unit testing aligns with an open-world approach, while system testing corresponds to a closed-world model where all dependencies are known beforehand.

Black Box vs White Box Testing

• Black box testing relies solely on specifications or input/output models without any internal code knowledge. Testers create scenarios based on expected outcomes rather than code structure.

• In contrast, white box testing involves analyzing the source code to identify complex areas and generate targeted test cases that cover various execution paths within the code.

Acceptance Testing: Guarantees and Levels

• Acceptance testing provides strong guarantees about product acceptance; passing these tests often serves as a contract for delivery.

• Smoke testing offers minimal assurance, serving primarily to verify basic functionality after changes without extensive validation.

Regression Testing Importance

• Regression testing ensures previously functioning features remain intact after new changes or updates are made to the software.

Understanding Test Compatibility and Execution

Test Compatibility Across Implementations

• Evidence suggests that behavior compatibility exists between different implementations of the same specification, particularly through regression testing, which ensures behavior preservation over time across system versions.

• Differential testing allows for comparison between two system versions operating on different platforms or devices, identifying situations where their behaviors may differ.

Categories of Testing Assurance

• Understanding various classifications related to testing assurance is crucial as many articles and studies utilize combinations of these categories.

Types of Test Execution

Automated vs. Manual Testing

• Tests can be executed either manually by a tester following a script or automatically by a computer program designed to perform the tests.

• Manual testing can be scripted step-by-step or exploratory, where testers verify new functionalities based on objectives rather than strict scripts.

Cost Implications of Testing Methods

• Automated tests are expensive to create due to the need for programming but are cost-effective in execution, allowing frequent daily runs after initial setup.

• The ability to run numerous regression tests efficiently is facilitated by automated systems once they are established.

Challenges in Testing

Complexity in Creating Tests

• Some tests can be complex and difficult to create, especially when determining if outputs from systems like voice recognition software are accurate.

Manual Testing Limitations

• While manual tests are cheaper to create (often just requiring a script), they can be costly in execution due to human involvement and potential oversight during test execution.