Unit Test Coverage Quiz

Code coverage measures the extent to which the codebase is tested by unit tests, indicating the percentage of code that has been executed during testing. High code coverage suggests that most of the code is being tested, potentially leading to fewer undiscovered bugs and higher software quality, while low coverage may indicate untested or risky areas.

Unit testing focuses on validating the functionality of individual components or modules in isolation. This ensures that each part of the application behaves as expected before integrating them into a larger system, allowing for easier identification and resolution of issues early in the development process.

An assertion in a unit test is a statement that checks whether a specific condition is true. If the condition is true, the test passes; if false, it fails. This mechanism helps ensure that the code behaves as expected, allowing developers to verify that the results of their code match the intended outcomes.

Unit tests are designed to verify the functionality of a single unit of code, such as a function or method. Testing multiple unrelated functions simultaneously can lead to confusion in identifying which function caused a failure, making it harder to isolate and fix issues. Therefore, unit tests should focus on one specific function at a time.

Test isolation in unit testing refers to the practice of testing a single unit of code independently from other components. This ensures that the tests evaluate the functionality of that unit without interference from external dependencies, leading to more reliable and accurate results. It helps identify issues within the unit itself, rather than in related code.

A mock object is a simulated object used in testing to mimic the behavior of real objects. It allows developers to isolate and test specific components of an application without relying on the actual implementations, facilitating efficient testing of interactions and ensuring that the system behaves as expected under various conditions.

A test fixture refers to the equipment and tools used to hold and support a device under test during the testing process. It ensures that tests are conducted consistently and accurately, providing a controlled environment for evaluating performance and functionality. This setup is essential for reliable and repeatable testing results.

100% code coverage means that every line of code has been executed during testing, but it does not ensure that all possible scenarios or edge cases have been tested. Bugs can still exist in untested paths, logic errors, or integration issues, making it impossible for code coverage alone to guarantee the absence of bugs.

Unit tests are designed to validate individual components or functions in isolation, ensuring that each part of the code behaves as expected under specific conditions. By focusing on one specific behavior or outcome, unit tests help identify issues early, making debugging easier and improving code reliability without being influenced by other system components.

A unit test that passes but fails to identify existing errors is termed a false positive. This situation occurs when the test incorrectly indicates that the code is functioning correctly, even though there are underlying issues. Such tests can create a false sense of security, leading developers to overlook potential bugs.

JUnit is a widely used framework in Java for unit testing, allowing developers to write and run repeatable tests. It provides annotations to define test methods, assertions to verify expected outcomes, and a rich ecosystem of tools that facilitate test-driven development, making it an essential component for ensuring code quality in Java applications.

Unit tests should be isolated and test individual components without relying on external systems like databases or APIs. This ensures that tests are fast, reliable, and can be executed in any environment without setup issues. Dependencies on external resources can introduce variability and make it difficult to pinpoint failures.