add unit tests

package.json

@@ -1,11 +1,12 @@
 {
   "name": "rxjs-animation-loop",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "description": "This module provides a game / animation loop based upon requestAnimationFrame.",
   "author": "Gareth Whittaker <[email protected]>",
   "scripts": {
     "compile": "babel src -d dist",
     "prepublish": "npm run compile",
+    "test": "ava src/index.spec.js",
     "example-multiple-subscribers": "npm run compile; node dist/examples/multiple-subscribers.js",
     "example-pausing-game-loop": "npm run compile; node dist/examples/pausing-game-loop.js"
   },
@@ -28,7 +29,9 @@
   },
   "license": "MIT",
   "devDependencies": {
+    "ava": "0.18.2",
     "babel-cli": "6.22.2",
-    "babel-preset-es2015": "6.22.0"
+    "babel-preset-es2015": "6.22.0",
+    "sinon": "1.17.7"
   }
 }

src/index.spec.js

@@ -0,0 +1,48 @@
+import test from 'ava'
+import sinon from 'sinon'
+import { Observable } from 'rxjs/Observable'
+import { BehaviorSubject } from 'rxjs/BehaviorSubject'
+import { animationLoop } from '../dist'
+
+let nextSpy
+let gameLoop
+
+test.beforeEach(t => {
+    nextSpy = sinon.spy(BehaviorSubject.prototype, 'next')
+
+    gameLoop = animationLoop()
+})
+
+test.afterEach(t => {
+    nextSpy.restore()
+})
+
+test('start', t => {
+    gameLoop.start()
+
+    t.true(nextSpy.calledOnce)
+    t.true(nextSpy.calledWithExactly(true))
+})
+
+test('stop', t => {
+    gameLoop.stop()
+
+    t.true(nextSpy.calledOnce)
+    t.true(nextSpy.calledWithExactly(false))
+})
+
+test('subscribe', t => {
+    const observerStub = sinon.stub()
+    const subscriberStub = sinon.stub()
+
+    const subscribeStub = sinon.stub(Observable.prototype, 'subscribe').returns(subscriberStub)
+
+    const gameLoopSubscriber = gameLoop.subscribe(observerStub)
+
+    t.true(subscribeStub.calledOnce)
+    t.true(subscribeStub.calledWithExactly(observerStub))
+
+    t.is(gameLoopSubscriber, subscriberStub)
+
+    subscribeStub.restore()
+})