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TDD - Test Driven Development in Swift (iOS) with Cuckoo, Quick and Nimble
This document discusses test-driven development (TDD). It provides an example of using TDD to develop a function to calculate the area of a square. The key steps are: 1) Write a test that fails for an initial function interface; 2) Implement the function to pass the test; 3) Refactor the code. It emphasizes writing tests before code, testing isolated units, and using a structured process of red-green-refactor cycles to develop code.
TDD - Test Driven Development in Swift (iOS) with Cuckoo, Quick and Nimble
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- 2. DRAFT INTERFACE WRITE TESTTHAT FAILS IMPLEMENT AND PASS THE TEST REFACTOR
- 3. func calculateAreaOfSquare(w: Int,h: Int) -> Double { } START FROM THE INTERFACE Given w=2, h=2, Expect area to be 4. WRITE FIRST TEST
- 4. IT FAILS. COMPILATION ERRORIS TDD ERROR func calculateAreaOfSquare(w: Int, h: Int) -> Double { }
- 5. START IMPLEMENTING func calculateAreaOfSquare(w:Int, h: Int) -> Double { return w * h }
- 6. IT PASSED. REFACTOR func calculateAreaOfRectangle(w:Int, h: Int) -> Double { } func calculateAreaOfSquare(w: Int, h: Int) -> Double { }
- 7. Given w=-1,h=-1, Expectarea to be 0. WRITE ANOTHER TEST
- 8. FAILS func calculateAreaOfRectangle(w: Int,h: Int) -> Double { return w * h } It returns 1
- 9. NEW IMPLEMENTATION func calculateAreaOfRectangle(w:Int, h: Int) -> Double { if w > 0 && h > 0 { return w * h } return 0 }
- 10. IT PASSED. REFACTOR CONTINUE THISCYCLE UNTIL ALL THE CRITERIA ARE MET
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- 12. DON’T MISS UNIT-TEST? DON’T MISS ANY REQUIREMENT!
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- 17. WHAT DOES TDDCOST ? WHEN TDD IS DONE CORRECTLY !
- 18. OTHERWISE… 10X OF WORKTHAN BEFORE
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- 20. TDD ONLY INTERFACE NEEDTO BE TESTED ▸ All the methods not used as interface should be private
- 21. TDD USE GOOD ARCHITECTURE ▸Less chance for big refactoring ▸ Less chance to destroy the tests VIP or VIPER
- 22. TDD DO REAL UNITTEST ▸ What is a unit ?
- 23. TDD Use interface(protocol) toisolate class to test
- 24. TDD Use interface(protocol) toisolate class to test
- 25. TDD let interactor =Interactor() interactor.presenter = MockPresenter() Verify function is called with parameter message interactor.presenter.presentError(message) verify(interactor.presenter.presentError(message))
- 26. TDD CREATE MOCK MANUALLYOR WITH TOOL ▸ Tool: Cuckoo ▸ https://github.com/Brightify/Cuckoo ▸ Auto-generate mock objects for Swift Protocol ▸ Simulate stub behaviors on each method ▸ Verify if a method is called with certain parameters
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- 28. TDD EFFECTIVE TESTS USINGXCTEST ▸ Test_MethodName_StateUnderTest_ExpectedBehavior Naming convention
- 29. TDD EFFECTIVE TESTS USINGXCTEST Arrange, Act, and Assert class BananaTests: XCTestCase { func testPeel() { // Arrange: Create the banana we'll be peeling. let banana = Banana() // Act: Peel the banana. banana.peel() // Assert: Verify that the banana is now edible. XCTAssertTrue(banana.isEdible) } }
- 30. TDD STRUCTURE TEST WITHTOOLS ▸ Tool: Quick & Nimble ▸ https://github.com/Quick/Quick ▸ Force developer adding clear comments for each key section
- 31. TDD STRUCTURE TEST WITHTOOLS ▸ Tool: Quick & Nimble func testDolphin_click_whenTheDolphinIsNearSomethingInteresting_isEmittedThreeTimes() { // ... } describe("a dolphin") { describe("its click") { context("when the dolphin is near something interesting") { it("is emitted three times") { // ... } } } }
- 32. TDD KEY ELEMENTS INQUICK ▸ describe closure: Describing Classes and Methods ▸ context closure: Specifying Conditional Behavior ▸ it closure: Assert if requirement is met describe("a dolphin") { describe("its click") { context("when the dolphin is near something interesting") { it("is emitted three times") { // verify or assert } } } }
- 33. TDD REAL-WORLD EXAMPLE ONUNIVADIS ▸ branch: feature/cuckoo
- 34. TDD ARE YOU READYFOR TDD ?