Tests help to make long-term product development cost effective rather than a cost centre, they underpin the effective flow of CI/CD and reduce failure demand on a team. But the discussion of unit testing goes further than simply doing it: what makes a good unit test? It is not enough to have tests; poor quality tests can hold back development just as good tests can streamline it.

This session looks at good unit tests (GUTs) and different testing workflows, from test-driven development (TDD) to refactoring-driven development, whether the code you are testing comes from the past, from a prompt or direct from your fingertips. Examples will be in C++, C and Python.

Agenda
• Kinds of tests
• Test-writing workflow: POUT, ITL, DDT, TDD and more
• What makes a unit test good?
• Common test smells and failure modes
• Tests as documentation and specification
• Given/When/Then and Arrange/Act/Assert test structure
• Aligning tests with domain concepts
• Data-driven tests
• Choices and checklists for test data
• Understanding (and misunderstanding) code coverage
• Structuring tests according to state models
• Grouping and nesting tests according to Given/When/Then
• Addressing brittle tests and long-term skipped tests
• Test strength: overfitting and underfitting tests
• Improving the design of your code by listening to your tests
• Dependency management and mocking
• Alternatives to mocking