use-arrange-act-assert-aaa

Summary

Structure every test case or test body into three distinct sections:

1. Arrange: Set up the test logic (inputs, mocks, data).
2. Act: Execute the function or method under test.
3. Assert: Verify the results against expected values.

Rationale

• Readability: A consistent visual structure reduces cognitive load when reading tests.
• Debugging: Clearly separates the "setup" failures from the "actual logic" failures.
• Focus: Encourages tests to focus on a single action (one "Act" per test).

Guidance

1. Visual Separation: Use blank lines to separate the three sections.
2. Comments (Optional): If the test is complex, you can explicitly add // Arrange, // Act, // Assert comments, but blank lines are usually sufficient.
3. Single Act: Ideally, there should be only one logical action in the Act phase.

Examples