Test Patterns

Arrange-Act-Assert (AAA) is a testing pattern that organizes unit tests into three clear phases: setting up data, executing the action, and verifying the result. It provides a predictable, readable structure for reliable test execution.

Test data builders and object mother patterns create flexible, reusable test objects with minimal duplication. Object mother composes complex test data scenarios, while builders provide a fluent API to construct customized test inputs for parameterized tests.

Use the Given-When-Then BDD pattern to write behavior-focused tests. This structure clearly documents test scenarios by specifying the initial context, the action taken, and the expected outcome, making tests more readable and maintainable.

Ensure test isolation and deterministic runs by using test fixtures and safe isolation practices. Fixtures provide a consistent, controlled environment for each test, preventing cross-test dependencies and unexpected state leakage during execution.

Spying on dependencies verifies specific interactions without replacing the entire dependency with full mocks. This approach maintains the real behavior of the dependency while confirming that your code interacts with it correctly, leading to more reliable tests.

Parameterized tests validate multiple scenarios efficiently by running the same test logic across different data sets. This pattern reduces code duplication and ensures comprehensive coverage of various test cases and edge conditions.