JS UNIT TESTING
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PART 1: JS Unit Testing
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- Intro to Mocha
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Test suite
- In Mocha, relates to a group of related tests!
- Test suite def is context specific.
// in the console
mocha <test_name.js>
For debugging... creating a test folder. For the example used:
test > utilities_spec.js // this relates to the utilities.js file
Mocha makes:
- Testing output easy to read
- Helps return the results in an informative way
- Test files are separated from the real code
- Guarantees code works as expected
- Instantly see if anything has broken when making changes
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- Different Types of Testing
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Unit Tests: Writing tests that confirm an individual function or piece of code as working how we want it to. Unit tests are like drills.
Integration Testing: Used to test new code added to pre-existing code and that they run correctly together without breaking.
End-To-End Testing: Running the application from start to finish to test everything that we can. Maybe only a few times run in a product cycle.
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- Behaviour Driven Dev
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BDD is an approach to building software.
- like creating a plan before writing a program
- write tests first, then code after
Refactoring:
- ticking off tests first
- refactoring to run faster later
- Write the tests, ever though they'll fail
- Write the easiest code to pass
- Go back and improve the code
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- Red, Green, Refactor
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Testing for title case
- Install Chai (expectation library)
- throws error is expectation is not met
npm install chai --save-dev touch textUtilites.js
// in textUtitlies.js
var expect = require('chai').expect;
expect(true).to.be.true;
function titleCase(title) { return title; }
expect(titleCase('the great mouse detective')).to.be.a('string');
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- Greater Expectations
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// in textUtitlies.js
var expect = require('chai').expect;
expect(true).to.be.true;
function titleCase(title) { var words = title.split(' '); var titleCasedWords = words.map(function(word) { return word[0].toUpperCase() + title.substring(1); });
return titleCasedWords.join(' ');
}
expect(titleCase('the great mouse detective')).to.be.a('string'); expect(titleCase('a')).to.equal('A'); expect(titleCase('vertigo')).to.equal('Vertigo'); expect(titleCase('the great mouse detective')).to.equal('The Great Mouse Detective');
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PART 2: Getting started with Chai and Mocha
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- Writing Test Suites
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- using battleship as an example
- refer to the code to have a look at how the test and actual implementation look
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PART 4: Going further
mocha --reporter min mocha --reporter markdown // for git
Check the websites.
Feel free to add it to your package.json file.
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- Outlining Your Test Suite
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Communicating test ideas before writing it.
- pending test spec
// gametest.js
var expect = require('chai').expect;
describe('GAME INSTANCE FUNCTIONS', function(){ describe('checkGameStatus', function() { it('should tell me when the game is over'); // no expectations yet. It is pending! }); });
Could also add an x... (in this eg, two pending)
xdescribe('GAME INSTANCE FUNCTIONS', function(){ describe('checkGameStatus', function() { it('should tell me when the game is over'); // no expectations yet. It is pending! }); });
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- Watching Test Files
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How to run auto run tests:
mocha --watch ./test/game_test.js ./game_logic/game_instance.js
// in package.json > scripts
"test:watch": "mocha --watch ./test ./"
npm run test:watch
You can even add other test:watch:name scripts to watch specific things at specific times!
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- Mocks and Stubs
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Advanced Features
- what happens if you have many dependencies?
- testing ones other than your test spec
Writing your own functions in the beforeEach() spec.
sinon.js is also a great framework for stubbing data.