TDD (Test Driven Development)

Basics

Have separate source and test folders. Test code should follow the structure of source.
Test should fail the first time it’s written/run.
Test names should reflect intent, and names should be expressive.
Refactor to remove duplicate code after passing test.
Re-run tests after every refactoring.
Only write new code when a test is failing. Each test should test new/different behavior.
Write the assertion first.
Minimize the assertions in each test.
All tests should pass before writing the next test.
Only refactor when all tests are passing.
Write the simplest code to pass the test.
Don’t introduce dependencies between tests. Test should pass when run in any order.
Tests should run fast. A slow test is a test that won’t get run.
Use mock objects to test code at system boundaries (e.g. database, container, file system) so that tests run fast.