В поисках качества JavaScript кода: модульное тестирование

Анна Хабибуллина

Transcript

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 Isol ated Consistent Responsibil ity Sel f-descr iptive NoexceptionHandl ing Use asser tions whenneeded
47. WRAPPING UP  Eachtestver ifies a smal lchunk ofcode  Unittests wor k bestinisol ation  Mocks, stubs and spies hel p toisol ate test  Don’ttestever ythingbutwr ite many tests  > 40 tool s ar e avail abl e to ease unittesting exper ience, soCHOOSE YOUR OWN!
48. SHWEEET
49. ͋Γ͕ͱ͏