Structured unit testing using SPEK (Droidcon SF 2019)

Transcript

1. Structured unit testing using Spek Martin Petrulak @martin_petrulak
2. Martin Petrulak Droidcon San Francisco 2019 Agenda • Drawbacks? of JUnit • Introduction of Spek • Project set-up • Core principles • How to write a test ( 2 distinct styles) • Specification • Gherkin • Wrap up & Questions
4. Martin Petrulak Droidcon San Francisco 2019 JUnit - Readability
5. Martin Petrulak Droidcon San Francisco 2019 Readability
6. Martin Petrulak Droidcon San Francisco 2019 JUnit - Reusability
7. Martin Petrulak Droidcon San Francisco 2019 Reusability
8. Martin Petrulak Droidcon San Francisco 2019 Parametrised tests
9. Martin Petrulak Droidcon San Francisco 2019 Parametrised tests
10. Martin Petrulak Droidcon San Francisco 2019 Parametrised tests
12. Martin Petrulak Droidcon San Francisco 2019 Spek • Unit testing framework • It’s DSL allows you to write nested tests • Uses JUnit 5 engine • JVM / Android / Multiplatform • JaCoCo, Assertions/Mocking - use whatever you like • 1st commit 16/12/2012 - Hadi Hariri (talking Kotlin) • 2 styles how to write tests : Specification & Gherkin
13. Martin Petrulak Droidcon San Francisco 2019 Setup - Project
14. Martin Petrulak Droidcon San Francisco 2019 Setup - Module
15. Martin Petrulak Droidcon San Francisco 2019 How to create a test • Extend : Spek{…} abstract class • Nesting functions • test{…} - assertions • group{…} - create hierarchy
16. Martin Petrulak Droidcon San Francisco 2019 How to create a test
17. Martin Petrulak Droidcon San Francisco 2019 Execution order
18. Martin Petrulak Droidcon San Francisco 2019 Execution order
19. Martin Petrulak Droidcon San Francisco 2019 Execution order • Discovery • Top down build test three • Execute code in groups • Top down execution of • Registered fixtures for scopes (setup/teardown case) • Tests (assertions)
20. Martin Petrulak Droidcon San Francisco 2019 Fixtures • before/afterGroup{…}. - only current scope • before/afterEachTest{…} - all current & nested scopes
21. Martin Petrulak Droidcon San Francisco 2019 Fixtures
22. Martin Petrulak Droidcon San Francisco 2019 Fixtures
23. Martin Petrulak Droidcon San Francisco 2019 Properties
24. Martin Petrulak Droidcon San Francisco 2019 Properties
25. Martin Petrulak Droidcon San Francisco 2019 Properties
26. Martin Petrulak Droidcon San Francisco 2019 Memoized delegate • Caching mode • TEST - new instance per test • EACH_GROUP - new instance per group • SCOPE - same instance in current group & subgroups • INHERIT - ???
27. Martin Petrulak Droidcon San Francisco 2019 Parametrised tests
28. Martin Petrulak Droidcon San Francisco 2019 How to run tests • Terminal • Plugin (recommenced)
29. Martin Petrulak Droidcon San Francisco 2019 How to run tests
30. Martin Petrulak Droidcon San Francisco 2019 Specification style • group{…} -> describe{…} or context{…} • test{…} -> it{…} • before/afterEachTest{…} -> before/afterEach{…} • before/afterGroup{…} -> before/after{…}
31. Martin Petrulak Droidcon San Francisco 2019 Specification style
32. Martin Petrulak Droidcon San Francisco 2019 Specification style
33. Martin Petrulak Droidcon San Francisco 2019 Specification style
34. Martin Petrulak Droidcon San Francisco 2019 Skipping tests
35. Martin Petrulak Droidcon San Francisco 2019 Skipping tests
36. Martin Petrulak Droidcon San Francisco 2019 Skipping tests
37. Martin Petrulak Droidcon San Francisco 2019 Gherkin • Written text - executable specification • Most of the lines start with a special keyword • Feature, Scenario, Given, When , Then, And • Keywords are translated to multiple languages
38. Martin Petrulak Droidcon San Francisco 2019 Gherkin - example Feature: Guess the word # The first example has two steps Scenario: Maker starts a game When the Maker starts a game Then the Maker waits for a Breaker to join # The second example has three steps Scenario: Breaker joins a game Given the Maker has started a game with the word "silky" When the Breaker joins the Maker's game Then the Breaker must guess a word with 5 characters
39. Martin Petrulak Droidcon San Francisco 2019 Gherkin • group{…} -> Feature{…} , Scenario{…} • test{…} -> Given{…}, When{…} And{…}, Then{…}
40. Martin Petrulak Droidcon San Francisco 2019 Gherkin
41. Martin Petrulak Droidcon San Francisco 2019 Gherkin
42. Martin Petrulak Droidcon San Francisco 2019 Gherkin
43. Martin Petrulak Droidcon San Francisco 2019 Gherkin
44. Martin Petrulak Droidcon San Francisco 2019 Gherkin
45. Martin Petrulak Droidcon San Francisco 2019 Gherkin disadvantages • Not so flexible regarding nesting • Default caching mode EACH_SCOPE -> test are not isolated ->if one test fails, its over • No build in mechanism for skipping • Given/When acts as a test in output and counts as a test
46. Martin Petrulak Droidcon San Francisco 2019 Gherkin advantages • Looks sexy :) • Easy to understand by non tech people
47. Martin Petrulak Droidcon San Francisco 2019 Summary • Nested test are easy to read -> understand -> review • Reusability made easy (memoized) • Write parametrised tests as normal Kotlin code • Not so many options as JUnit 5 to fine tune • Specification vs Gherkin • Can exist alongside existing JUnit tests -> give it a shot
48. Martin Petrulak Droidcon San Francisco 2019 Advices / Best practices • println(…) is your friend • never interact with property outside of before/after..{…} • one assertion per test( it{…},Then{…}, And{…} ) • use test{…} only for assertions
49. Martin Petrulak Droidcon San Francisco 2019 Resources • https://spekframework.org/ • https://github.com/spekframework/spek/ • https://cucumber.io/docs/gherkin/ • https://github.com/Petrulak/android-mvvm-spek • //TODO slides link @martin_petrulak
50. Martin Petrulak Droidcon San Francisco 2019
51. Martin Petrulak Droidcon San Francisco 2019 –me “ Thank you very much ! Question time :) ”