Flutter Test Pyramid Sayeed & Chandru 

Ground Rules Feel free to stop us if you don’t understand something Let’s keep it interactive No question is silly 

Q. What is a test in developer terminology 

A Some code to AUTOMATICALLY validate some other code 

Different kinds of tests Unit Tests UI Tests Integration Tests Functional Tests Snapshot Tests * Contract Tests * Performance Tests 

Comparison of Various Types Of Tests Speed Feedback Cycle Confidence Flakiness/Dep endencies Cost of Maintenance Unit Fast Fast Low Low Low Integration Fast Fast Medium Medium Medium Functional Slow Slow High High High 

Principles of Test Distribution Based on the trade-offs, an ideal test distribution should optimize for * Maximum Unit tests * Sufficient Functional tests to cover important app flows Required number integration tests When we do this, the shape of test distribution generally turns out to be a PYRAMID 

Q. What is a test pyramid 

A. Way to distribute different kinds of tests 

Test Distribution Anti-Patterns 

Agenda How to distribute tests for a Flutter app across different layers of tests 

Before We Dive Into Code Let’s understand the importance of App Architecture in achieving test pyramid 

Application Architecture & Test Pyramid Layering your app correctly using SOLID principles makes achieving the right test pyramid 

Common Architecture Anti-patterns - Difficulty In Testing Logic code in UI classes UI classes hard & slow to test Lack Of Dependency Injection - We end up integration testing instead of unit - Test setup becomes difficult 

Sample App Architecture - Single Responsibility Principle - Dependency Inversion - bLoc pattern with Reactive State Management - Dependency Injection - Clean Architecture Layers - data, domain, presentation 

HandsOn What to test, Which layer of test pyramid to test it in 

Q. What all do we need to test in the product list screen - 

A. 

Sample App Architecture Walkthrough 

Unit Tests 

Widget Tests - ProductListTest - What to test [branch widget_test_1] - ProductListItemTest - What to test [branch widget_test2] - ProductListScreenTest - What to test [branch widget_test3] 

Integration Tests Actually they are Functional Tests - They require a real device to run on - They are much slower - Multiple tests in a _test file depend on each other in terms previous state - Hard to change application setup from test file - Hard to debug failing test. Error messages not descriptive enough 

Golden File Tests Q. When to use Golden File Tests A. Keep it minimal. Test only critical functionality where alignment/size of UI controls could be a make or break scenario. a. [Should Test] Add To Cart button size as without this you get no money b. [Should Not Test] Profile page - They can be flaky as even 1px misalignment causes failure - Need to maintain golden images in CI which can increase repo size [branch golden_test_1] 

References Talk to Us On Gitter -> https://gitter.im/gdg-flutter-test-pyramid/community See The Code Here -> https://github.com/sayeedhussain/flutter_test_pyramid_gdg Thank You