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Js fwdays unit tesing javascript(by Anna Khabibullina)

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See video from JS Frameworks Day, April 2014 …

See video from JS Frameworks Day, April 2014
https://www.youtube.com/watch?v=edOIMiQFZ2w&list=UU3NDbeN0Jq_InNAhiJtvHcQ

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  • 1. В поисках качества JavaScript: модульное тестирование Анна Хабибуллина DA-14 / da-14.com anna.khabibullina@da-14.com akhabibullina _khabibullina
  • 2. ZE QUALITYS? “Any feature without a test doesn’t exist” Steve Loughran HP Laboratories
  • 3. AGENDA  Unit Testing Concept  Pros & Cons  Basic Terms & Structure  TDD &/vs. BDD  Tools & Libraries  Unit Testing Specifics in JavaScript  Best Practices
  • 4. UNIT TESTING CONCEPT Unit testing is a method by which individual units of source code are tested to determine if they are fit for use.
  • 5. WHY UNIT TESTING? Unit tests find problems early in the development cycle (TDD & BDD) Refactoring Integration Documentation Better design
  • 6. IS UNIT TESTING A GOOD INVESTMENT?  slow down the development process  share the same blind spots with the code  doesn’t prove that they’re compatible with one another or configured correctly
  • 7. BASIC TERMS
  • 8. In simple words, the goal of assertion is to forcefully define if the test fails or passes. STATEMENT PASSES FAILS x = 1 assert(x > 0) assert(x < 0) expect(4+5).to.equal(9); ASSERTION
  • 9. function initialize() { // The initialization was successful. return true; } Given the function initialize(): ASSERTION: EXAMPLE
  • 10. ASSERTION: EXAMPLE var isInitialized = initialize(); TDD assert.isTrue(isInitialized) BDD expect(isInitialized).to.be.true Check that function initialize() returns true when called.
  • 11. FIXTURE A test fixture is a fixed state of the software under test used as a baseline for running tests. In JavaScript for client side: simulate AJAX responses; loading known set of data such as html objects.
  • 12. FIXTURE: EXAMPLE Require the piece of markup stored in myfixturemarkup.html file before each test: beforeEach(function() { loadFixtures('myfixturemarkup.html'); });
  • 13. STUB Method stubs are functions with pre- programmed behavior.
  • 14. STUB: EXAMPLE Forcing a method to throw an error in order to test error handling. var fn = foo.stub().throws(Error); expect(fn).to.throw(Error);
  • 15. SPY A test spy is a function that records arguments, return value, the value of this and exception thrown (if any) for all its calls.
  • 16. SPY: EXAMPLE Test that a function cursor.hide() has been only called once, and only once. sinon.spy(cursor, "hide"); TDD sinon.assert.calledOnce(cursor.hide) BDD expect(cursor.hide.calledOnce).to.be.true
  • 17. MOCK Mocks are fake objects with pre- programmed behavior (like stubs) and pre-programmed expectations. They are like both stubs and spies – in one.
  • 18. MOCK: EXAMPLE Create an expectation that jQuery.each is called once, and only once, and also instructs the mock to behave as we pre- define. var mock = sinon.mock(jQuery);
  • 19. MOCK: EXAMPLE #1 – which method? #2 – how many times it is called? #3 – what are the arguments when the method called? #4 – what the method returns?
  • 20. TEST DRIVEN DEVELOPMENT(TDD) TDD is a software development process that… I’ll tell you the rest 
  • 21. WHAT ARE THESE BDD?
  • 22. ALRIGHT, WHAT IS BDD YOU ASK? Terminology: TDD BDD Test Example Assertion Expectation Unit Behavior
  • 23. BASIC STRUCTURE #1. Setup/BeforeEach/Before #2. Prepare an input #3. Call a method #4. Check an output #5. Tear down/AfterEach/After
  • 24. #1. Setup / Before before(function(done) { // Create a basic document. document = jsdom.jsdom(); window = document.parentWindow; done(); }); BASIC STRUCTURE: EXPLAINED
  • 25. Before / BeforeEach before(function() { console.log(‘before test’); }); test(‘first test’, function() { console.log(‘first test’); }); test(‘second test’, function() { console.log(‘second test’);}); afterEach(function() { console.log(‘after each test’); }); Result before test first test after each test second test after each test BASIC STRUCTURE: EXPLAINED
  • 26. BASIC STRUCTURE: EXPLAINED it('should initialize cursor if zoom level >= minimum zoom level.', #2. Prepare an input and predicted result. var minZoomLevel = 1; var zoomLevel = minZoomLevel + 0.1; var expectedCursor = {‘color’: ‘white’, ‘height’: … }; #3. Call a method. var actualCursor = cursor.init(zoomLevel); #4. Check an output. expect(actualCursor).to.deep.equal(expectedCursor); done(); }); function(done) {
  • 27. BASIC STRUCTURE: EXPLAINED it('should initialize cursor if zoom level >= minimum zoom level.', #2. Prepare an input and predicted result. var minZoomLevel = 1; var zoomLevel = minZoomLevel + 0.1; var expectedCursor = {‘color’: ‘white’, ‘height’: … }; #3. Call a method. var actualCursor = cursor.init(zoomLevel); #4. Check an output. expect(actualCursor).to.deep.equal(expectedCursor); done(); }); function(done) {
  • 28. BASIC STRUCTURE: EXPLAINED it('should initialize cursor if zoom level >= minimum zoom level.', #2. Prepare an input and predicted result. var minZoomLevel = 1; var zoomLevel = minZoomLevel + 0.1; var expectedCursor = {‘color’: ‘white’, ‘height’: … }; #3. Call a method. var actualCursor = cursor.init(zoomLevel); #4. Check an output. expect(actualCursor).to.deep.equal(expectedCursor); done(); }); function(done) {
  • 29. BASIC STRUCTURE: EXPLAINED it('should initialize cursor if zoom level >= minimum zoom level.', #2. Prepare an input and predicted result. var minZoomLevel = 1; var zoomLevel = minZoomLevel + 0.1; var expectedCursor = {‘color’: ‘white’, ‘height’: … }; #3. Call a method. var actualCursor = cursor.init(zoomLevel); #4. Check an output. expect(actualCursor).to.deep.equal(expectedCursor); done(); }); function(done) {
  • 30. #5. TearDown / After after(function(done) { // Remove global objects document. document = null; window = null; done(); }); BASIC STRUCTURE: EXPLAINED
  • 31. OUTPUT
  • 32. <testsuite name="Macchiato Tests" tests="13" failures="0" errors="0" skipped="0" timestamp="Mon, 02 Dec 2013 11:08:09 GMT" time="0.114"> <testcase classname = "cursor #init ()" name = "should initialize cursor if zoom level &gt; minimum zoom level." time="0.004"/> </testsuite> OUTPUT: SUCCESS
  • 33. <failure classname="cursor #init()" name="should initialize cursor if zoom level &gt; minimum zoom level." time="0" message="Cannot read property 'show' of undefined"><![CDATA[TypeError: Cannot read property 'show' of undefined // ..... Exception Stack Trace ..... </failure> OUTPUT: FAILURE
  • 34. TOOLS
  • 35. TOOLS > 40 frameworks & libraries qUnit(TDD) light-weight TDD framework Jasmine(BDD) flexible BDD framework Mocha / Karma test runner for async code + Chai TDD / BDD assertion library + Sinon test spies, stubs & mocks
  • 36. ENTIRE SPACE OF FRAMEWORKS…
  • 37. HOW DO I UNIT TEST Known Frameworks / Libraries? What to test? What to use? Angular, React, Flight Karma + Jasmine Backbone qUnit Ember Karma + qUnit (ember-app-kit) ExtJs Jasmine, Siesta (UI) TypeScript tsUnit CoffeeScript qUnit Dart Unittest, Hop and Drone.io NodeJs expresso and vows, Nodeunit
  • 38. TOOLS: WHAT WE USE  Run UT: Mocha  Run UT in parallel: Macchiato  Assert/Expect: Chai  W3C DOM in JavaScript: Jsdom  Mock, spy, stub: Sinon  Code coverage tool: None  Routine automation: make/Grunt
  • 39. TOOLS: WHAT WE USE
  • 40. TOOLS: WHAT WE USE Project unit tested like a dream ♥
  • 41. UNIT TESTING SPECIFICS IN JAVASCRIPT UI Load fake data via “fixtures” Jsdom(W3C JavaScript implementation)
  • 42. UNIT TESTING SPECIFICS IN JAVASCRIPT AJAX Stub jQuery.ajax Fake XMLHttpRequest (XMLHTTP ActiveXObject) Fake server
  • 43. UNIT TESTING SPECIFICS IN JAVASCRIPT 3rd-party scripts Stubbing jQuery plugin functions (mock jQuery.fn)
  • 44. UNIT TESTING SPECIFICS IN JAVASCRIPT Dependency Injection Mocking deps in RequireJs sucks hard! Squire.js lib / testr.js
  • 45. UNIT TESTING SPECIFICS IN JAVASCRIPT NodeJs Server-side specifics rewire: node.js dependency injection
  • 46. BEST PRACTISES Fast Isolated Consistent Responsibility Self-descriptive No exception Handling Use assertions when needed
  • 47. WRAPPING UP  Each test verifies a small chunk of code  Unit tests work best in isolation  Mocks, stubs and spies help to isolate test  Don’t test everything but write many tests  > 40 tools are available to ease unit testing experience, so CHOOSE YOUR OWN!
  • 48. SHWEEET
  • 49. ありがとう

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