TDD Styles

State Verification versus Behaviour Verification.
Discovery Testing.

Transcript

1. TDD-Styles State Verification Behaviour Verification Discovery Testing Stefan Scheidt, REWE digital
2. TDD stands for ... ... Test Driven Development or ... Test Driven Design
3. TDD Primer • Write a failing unit test • Make the test pass • Refactor • Repeat
4. Test Phases • Arrange/Given • Act/When • Assert/Then
5. Stubbing and Mocking • Stub: providing "indirect input" • Stubbing: Configure a Stub • Mock: allows observation of "indirect output" • Mocking: describing mandatory interactions (Spock) See also Wikipedia
6. State Verification • "Classic TDD", "Detroit-School TDD" • mostly bottom-up / inside-out • uses stubs, but avoids mocking • design emerges through frequent iterative refactoring See Testdoubles Notes on Testing
7. Behavior Verification • "Mockists TDD", "London-School TDD" • mostly top-down / outside-in • uses mocking intensively • design emerges through iterating on the interaction between collaborators See Testdoubles Notes on Testing and Mocks Aren't Stubs
8. GOOS Growing Object Oriented Software, Guided by Tests
9. Discovery Testing Defined by Justin Searls 1. Start by identifying an entry point and write a collaboration test 2. For each dependency the first collaboration test identifies: a. if it needs to be broken down, write another collaboration test b. if its task is "logic", implement it with classic TDD c. if it interacts with third-party, implement a wrapper object
10. Discovery Testing In Discovery Testing, objects are either one of • "Collaborators", tested with Mocks • "Logic Leaf Nodes", tested with classic TDD • "Wrapper", tested with integration tests • Value Objects passed as arguments and return values
11. Discovery Testing
12. Demo: Game of Life
14. The End
15. Thank you! Contact: stefanscheidt on Twitter and GitHub