9 Common Misconceptions about TDD

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1. 9 Common Misconceptions about TDD MAGE TEST FEST
2. Fabian Schmengler Developer and partner at integer_net Testing Magento since 2011 @fschmengler
3. Disclaimer: Beware of straw men Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
4. ☼ EINS I have tests, thus I do TDD Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
5. TDD Test rst Tests guide development Not TDD Test after Test verify development Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
6. ☼ ZWEI Write test, then implement feature Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
7. Red-Green-Refactor In Short Cycles! 1. Write failing test 2. Make it pass 3. Make it good Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
8. Red-Green-Refactor In Short Cycles! 1. Write failing test ⬅ one little test at at time 2. Make it pass 3. Make it good Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
9. Red-Green-Refactor In Short Cycles! 1. Write failing test ⬅ one little test at at time 2. Make it pass ⬅ stupid hacky solution 3. Make it good Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
10. Red-Green-Refactor In Short Cycles! 1. Write failing test ⬅ one little test at at time 2. Make it pass ⬅ stupid hacky solution 3. Make it good ⬅ well designed solution Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
11. ☼ DREI No code is ever written without tests Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
12. Experiments, "Spikes" Try out the framework Proof of concept Throwaway code Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
13. Other ways to experiment Exploratory tests Use failing assertions to see real results of unknown operation. e.g.: $this->assertEquals([[], [], []], $result); REPL (Read-Execute-Print-Loop) JS: browser console PHP: n98-magerun2 dev:console Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
14. ☼ VIER When the tests pass, we are done Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
15. Iterative vs. Incremental Always refactor Started with a stupid solution Design evolves through refactoring Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
16. Changeability & Replacability GeePaw Hill @GeePawHill If I change out of my galoshes and in to my tennis shoes, I'm preparing to move faster. Sure, I could run the race in my galoshes. Sure, it will take me a few seconds to take them off. But I'm betting that the cost of changing the shoes will be more than made up during the race. 9 13:32 - 18. Jan. 2019 Weitere T weets von GeePaw Hill ansehen GeePaw Hill @GeePawHill · 18. Jan. 2019 Antwort an @GeePawHill It really is just that simple, not rocket science but basic efficiency: people make this kind of decision every day, where they enhance their performance by doing things that are not themselves performing. Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
17. ☼ FÜNF TDD is a testing technique Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
18. Test Driven A way to write code Tests are means to an end (and a welcome side effect) Development ⬆ Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
19. ☼ SECHS No upfront design needed Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
20. TDD does not replace Requirement analysis Domain Modeling System Design API Design => WHAT to build Architects are not becoming unemployed Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
21. ☼ SIEBEN Mock all the collaborators Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
22. Isolation Isolation From WHAT? External resources: certainly Framework: mostly Except for integration tests Libraries: rather not No implementation details. Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
23. Avoid the Mocking Hell Keep Magento dependencies to a minimum Mock/stub service contracts (API interfaces), not concrete classes Write adapters for complex or insu cient API Mock or fake those Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
24. ☼ ACHT A unit is a class Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
25. Unit Test Subject Public API of components e.g. Service as Facade, and its return types No unit tests for framework integration layer: Controllers Plugins Observers Blocks Resource Models, Repositories Those remain dumb and use our components. Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
26. Unit Test Test behavior, not implementation 1 Test Case != 1 Class 1 Test != 1 Method Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
27. Example feature: Subscriptions Orders can be turned into subscriptions Subsequent orders are placed automatically Behavior to test A subscription is created if an order has been marked as subscription during checkout Orders are created for active subscriptions with due date Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
28. Subscriptions ├── Cron │ └── HandleSubscriptionsCron.php ⬅ integration layer ├── Model │ ├── CreateSubscription.php ⬅ services as public API │ ├── CreateOrders.php │ ├── Subscription.php ⬅ implementation details │ ├── SubscriptionPeriod.php │ ├── SubscriptionStatus.php │ ├── SubscriptionRepository.php ⬅ integration layer, mocked in test │ └── SubscriptionRepositoryInterface.php ├── Plugin │ └── PlaceOrderPlugin.php ⬅ integration layer └── Test ├── Unit │ ├── CreateSubscriptionTest.php ⬅ test behavior │ └── CreateOrdersTest.php └── Integration ├── CronTest.php ⬅ test framework integration ├── PlaceOrderTest.php └── SubscriptionRepositoryTest.php Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
29. Subscriptions ├── Cron │ └── HandleSubscriptionsCron.php ⬅ integration layer ├── Model │ ├── CreateSubscription.php ⬅ services as public API │ ├── CreateOrders.php` │ ├── Subscription.php ⬅ implementation details │ ├── SubscriptionPeriod.php │ ├── SubscriptionStatus.php │ ├── SubscriptionRepository.php ⬅ integration layer, mocked in test │ └── SubscriptionRepositoryInterface.php ├── Plugin │ └── PlaceOrderPlugin.php ⬅ integration layer └── Test ├── Unit │ ├── CreateSubscriptionTest.php ⬅ test behavior │ └── CreateOrdersTest.php` └── Integration ├── CronTest.php ⬅ test framework integration ├── PlaceOrderTest.php └── SubscriptionRepositoryTest.php Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
30. Subscriptions ├── Cron │ └── HandleSubscriptionsCron.php ⬅ integration layer ├── Model │ ├── CreateSubscription.php ⬅ services as public API │ ├── CreateOrders.php │ ├── Subscription.php ⬅ implementation details │ ├── SubscriptionPeriod.php │ ├── SubscriptionStatus.php │ ├── SubscriptionRepository.php ⬅ integration layer, mocked in test │ └── SubscriptionRepositoryInterface.php ├── Plugin │ └── PlaceOrderPlugin.php ⬅ integration layer └── Test ├── Unit │ ├── CreateSubscriptionTest.php ⬅ test behavior │ └── CreateOrdersTest.php └── Integration ├── CronTest.php ⬅ test framework integration ├── PlaceOrderTest.php └── SubscriptionRepositoryTest.php Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
31. Subscriptions ├── Cron │ └── HandleSubscriptionsCron.php ⬅ integration layer ├── Model │ ├── CreateSubscription.php ⬅ services as public API │ ├── CreateOrders.php │ ├── Subscription.php ⬅ implementation details │ ├── SubscriptionPeriod.php │ ├── SubscriptionStatus.php │ ├── SubscriptionRepository.php ⬅ integration layer, mocked in test │ └── SubscriptionRepositoryInterface.php ├── Plugin │ └── PlaceOrderPlugin.php ⬅ integration layer └── Test ├── Unit │ ├── CreateSubscriptionTest.php ⬅ test behavior │ └── CreateOrdersTest.php └── Integration ├── CronTest.php ⬅ test framework integration ├── PlaceOrderTest.php └── SubscriptionRepositoryTest.php Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
32. Exception Testing implementation details can aid development and small scale refactoring. BUT those tests can be thrown away when their job is done! Otherwise they stay only as maintenance burden. Let them go! Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
33. ☼ NEUN BDD is better than TDD Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
34. TDD Helps with code design Focus on developers BDD/ATDD Helps with requirement analysis Focus on users Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
35. Test Behavior Ideas are not contradictional! With TDD we should test behavior as well And why not both? Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
36. Tests in Natural Language Who is really writing their tests together with the customer? Expressive test code is possible without Gherkin Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
37. Gherkin Scenario 1: Refunded items should be returned to stock Given that a customer previously bought a black sweater from me And I have three black sweaters in stock. When they return the black sweater for a refund Then I should have four black sweaters in stock. PHPUnit public function test_refunded_items_should_be_returned_to_stock() { $this->given_that_a_customer_previously_bought_a_black_sweater_from_me(); $this->and_I_have_three_black_sweaters_in_stock(); $this->when_they_return_the_black_sweater_for_a_refund(); $this->then_I_should_have_four_black_sweaters_in_stock(); } Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
38. ☼ AUS Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
39. Coming soon when it's done: Test Driven Magento by Example https://tddwizard.com/ @fschmengler Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler
40. Image sources Rammstein concert: Matt Foster CC-BY 2.0 (colors modi ed) Cliparts: pixaby.com (Pixaby Licence, free for commercial usage) Fabian Schmengler /> 9 Common misconceptions about TDD @fschmengler