Test Driven Development with JavaScript
Author: Andrey Kucherenko
TDD steps
-
Navigation map
-
Test first
-
Assert first
-
Fail first
Test first
describe('Calculator', () => {
it('should summarize two numbers', () => {
});
});Assert first
describe('Calculator', () => {
it('should summarize two numbers', () => {
sut.sum(1, 2).should.equal(3);
}
);
});Fail first
> mocha --require babel-polyfill --compilers js:babel-register test/*.spec.js
․
0 passing (4ms)
1 failing
1) String Calculator "before each" hook:
ReferenceError: Calculator is not defined
at Context.<anonymous> (/home/apk/workspace/lab/tdd/test/Calculator.spec.js:5:15)
at callFn (/home/apk/workspace/lab/tdd/node_modules/mocha/lib/runnable.js:223:21)
at Hook.Runnable.run (/home/apk/workspace/lab/tdd/node_modules/mocha/lib/runnable.js:216:7)
at next (/home/apk/workspace/lab/tdd/node_modules/mocha/lib/runner.js:258:10)
at Object._onImmediate (/home/apk/workspace/lab/tdd/node_modules/mocha/lib/runner.js:275:5)
at processImmediate [as _immediateCallback] (timers.js:330:15)
Benefits
-
Unit tests coverage
-
Increases assurance of correctness
-
More complete explorations of requirements
-
Improved code
-
Code as documentation
-
Safe refactoring
- No extra code
Pair programming
Pair Programming Rules
- Ping Pong
- Silent coding
- Evil coder
- Baby steps
- ...
I don't use Pair Programming when:
- Build nonproduction code
- Work on spikes for future stories
- Learn new tool or technique
- Improve existing test coverage or fix code violations
Pair Programming Smells
- Unequal access
- Domination
- Unhealthy relationship
- Every player play his game
- Endless debate
Emergent Design
Continious integration
Show me the source!
grunt-mutation-testing
coverage-blamer
Enzyme
chai.should();
beforeEach(() => {
window.env = sinon.sandbox.create();
});
afterEach(() => {
window.env.restore();
});
test_config.js
it('should show spy', () => {
const callback = sinon.spy();
PubSub.subscribe("message", callback);
PubSub.publishSync("message");
assertTrue(callback.called);
});it('should show stub', () => {
const message = 'an example message';
const stub = sinon.stub().throws();
const spy1 = sinon.spy();
const spy2 = sinon.spy();
PubSub.subscribe(message, stub);
PubSub.subscribe(message, spy1);
PubSub.subscribe(message, spy2);
PubSub.publishSync(message, undefined);
spy1.should.have.been.called;
spy2.should.have.been.called;
stub.should.have.been.calledBefore(spy1);
});it('should show stub', () => {
const myAPI = { method: () => {} };
const spy = sinon.spy();
const mock = sinon.mock(myAPI);
mock.expects("method").once().throws();
PubSub.subscribe("message", myAPI.method);
PubSub.subscribe("message", spy);
PubSub.publishSync("message", undefined);
mock.verify();
assert(spy.calledOnce);
});