AAA Unit Tests

Use Arrange, Act, and Assert when writing unit tests.

The pattern

1. Arrange - prepares everything the test needs.
2. Act - executes the action to test the code.
3. Assert - applies expectations to the result.

Always separate each step with a blank line and a comment. Sometimes, when tests are very simple and some steps can be written as one-liners, do it, and use a comment like "Act & Assert".

Rules