Too many mocks killed the test: What Hexagonal Architecture has changed

Video : https://youtu.be/rSO1y3lCBfk
ForumPHP 2020 : https://afup.org/talks/3414-trop-de-mock-tue-le-test-ce-que-l-archi-hexagonale-a-change
Github demo project : https://github.com/JMLamodiere/tdd-demo-forumphp2020

French version: https://speakerdeck.com/jmlamodiere/trop-de-mock-tue-le-test-ce-que-larchi-hexagonale-a-change

Transcript

1. Icons made by Icongeek26, Freepik from www.flaticon.com
2. Locking Tests vs. TDD Icons made by Roundicons from www.flaticon.com
3. Icons made by Freepik from www.flaticon.com https://github.com/JMLamodiere/tdd-demo-forumphp2020
4. Previously...
5. • A Functional Test describes a functionality • A Unit Test locks an implementation Prejudice #1 Icons made by Freepik from www.flaticon.com
6. • A Functional Test describes a behaviour • A Unit Test locks an implementation Prejudice #1 Icons made by Roundicons from www.flaticon.com All tests describe the expected public behaviour Only the audience and the size of the covered area vary
7. Only functional tests have 3 steps: • Given • When • Then Prejudice #2 Icons made by Freepik from www.flaticon.com
8. Only functional tests have 3 steps: • Given • When • Then Prejudice #2 Icons made by Roundicons from www.flaticon.com All tests follow the narrative structure: • Given = Arrange • When = Act • Then = Assert Setup Catalyst Resolution
9. Prejudice #3 Icons made by Freepik from www.flaticon.com Checking the number of calls to all mocked methods increases my confidence. ->expects($this->exactly(1))->method('xxx') ->shouldBeCalledTimes(1)
10. Prejudice #3 Checking the number of calls to all mocked methods increases my confidence ->expects($this->exactly(1))->method('xxx') ->shouldBeCalledTimes(1) Icons made by Roundicons, Smashicons from www.flaticon.com • Blurs the intent of the test • Locks implementation details • Impossible to write first
11. What to test ?
12. Prejudice #4 Icons made by Freepik from www.flaticon.com I can mock the libraries used on the Infrastructure side : • Http : Guzzle… • Database : Doctrine, Eloquent…
13. Prejudice #4 Icons made by Roundicons, Smashicons from www.flaticon.com I can mock the libraries used on the Infrastructure side : • Http : Guzzle… • Database : Doctrine, Eloquent… • Coupled with the usage details of the lib • Assumptions about the way it behaves • Impossible to write first
14. Infrastructure : Integration Tests Icons made by Freepik, Smashicons, Roundicons from www.flaticon.com
15. Prejudice #5 Icons made by Freepik from www.flaticon.com Functional Test = necessarily end to end
16. Prejudice #5 Icons made by Roundicons, smashicons from www.flaticon.com Functional Test = necessarily end to end • Slow • Brittle • Difficult to maintain • Harder to write first • Locks Infrastructure choices too soon Suggestion : mock Secondary Ports
17. Icons made by Freepik from www.flaticon.com Suggestion
18. I must know the splitting between my classes before I write my tests Prejudice #6 Icons made by Freepik from www.flaticon.com
19. I must know the splitting between my classes before I write my tests Prejudice #6 Icons made by Roundicons from www.flaticon.com • Prod classes splitting != test classes splitting • Start with an area with a known boundary
20. Icons made by Freepik from www.flaticon.com 1st test: area with a known boundary
21. Prejudice #7 Icons made by Freepik from www.flaticon.com If I don't mock my Entities / DTOs, too many tests will break if I add a field
22. Prejudice #7 Icons made by Roundicons from www.flaticon.com If I don't mock my Entities / DTOs, too many tests will break if I add a field • Use test Factori(es) with optional fields • Getter not covered ? I remove it
23. Thanks! Icons made by Roundicons, Freepik from www.flaticon.com It’s your turn ! • •