Track active observables & fix tests (#321)

src/index.js

@@ -1,5 +1,15 @@
 import {install} from '@sinonjs/fake-timers'
 
+function extend(target /*, mixin1, mixin2... */) {
+  for (let i = 1; i < arguments.length; i++) {
+    for (const prop in arguments[i]) {
+      target[prop] = arguments[i][prop]
+    }
+  }
+
+  return target
+}
+
 const throwEventTypeError = event => {
   throw new TypeError(`Expected event object, received:
 ${JSON.stringify(event, null, '  ')}`)
@@ -207,10 +217,31 @@ export default function createTestHelpers(Kefir) {
     return log
   }
 
+  const observables = {
+    active: [],
+    clear: function() {
+      this.active = []
+    },
+  }
+
+  const {_onActivation, _onDeactivation} = Kefir.Observable.prototype
+
+  extend(Kefir.Observable.prototype, {
+    _onActivation() {
+      observables.active.push(this)
+      _onActivation.apply(this)
+    },
+    _onDeactivation() {
+      observables.active.splice(observables.active.indexOf(this), 1)
+      _onDeactivation.apply(this)
+    },
+  })
+
   return {
     END,
     VALUE,
     ERROR,
+    observables,
     send,
     parseDiagram,
     sendFrames,

test/kefir-test-utils.spec.js

@@ -8,6 +8,7 @@ describe('kefir-test-utils', () => {
     END,
     VALUE,
     ERROR,
+    observables,
     send,
     parseDiagram,
     sendFrames,
@@ -24,6 +25,141 @@ describe('kefir-test-utils', () => {
     watchWithTime,
   } = createTestUtils(Kefir)
 
+  beforeEach(() => {
+    observables.clear()
+  })
+
+  afterEach(() => {
+    expect(observables.active.length).to.equal(0, 'Expected 0 active observables after test execution.')
+  })
+
+  describe('activeObservables', () => {
+    const noop = () => {}
+
+    describe('Observable', () => {
+      it('counts active observables', () => {
+        const observable = new Kefir.Observable()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+      })
+
+      it('counts all observable activations', () => {
+        const observable = new Kefir.Observable()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+
+      it('multiple subscriptions do not count as multiple active observables', () => {
+        const observable = new Kefir.Observable()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.onError(noop)
+        expect(observables.active.length).to.equal(1)
+
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offError(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+    })
+
+    describe('Property', () => {
+      it('counts active observables', () => {
+        const observable = new Kefir.Property()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+      })
+
+      it('counts all observable activations', () => {
+        const observable = new Kefir.Property()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+
+      it('multiple subscriptions do not count as multiple active observables', () => {
+        const observable = new Kefir.Property()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.onError(noop)
+        expect(observables.active.length).to.equal(1)
+
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offError(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+    })
+
+    describe('Stream', () => {
+      it('counts active observables', () => {
+        const observable = new Kefir.Stream()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+      })
+
+      it('counts all observable activations', () => {
+        const observable = new Kefir.Stream()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+
+      it('multiple subscriptions do not count as multiple active observables', () => {
+        const observable = new Kefir.Stream()
+        expect(observables.active.length).to.equal(0)
+
+        observable.onValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.onError(noop)
+        expect(observables.active.length).to.equal(1)
+
+        observable.offValue(noop)
+        expect(observables.active.length).to.equal(1)
+        observable.offError(noop)
+        expect(observables.active.length).to.equal(0)
+      })
+    })
+  })
+
   describe('observable creators', () => {
     it('should create a prop', () => {
       expect(prop()).to.be.instanceof(Kefir.Property)
@@ -41,10 +177,16 @@ describe('kefir-test-utils', () => {
   describe('send', () => {
     let log, obs
 
+    const fn = val => log.push(val)
+
     beforeEach(() => {
       log = []
       obs = stream()
-      obs.onAny(val => log.push(val))
+      obs.onAny(fn)
+    })
+
+    afterEach(() => {
+      obs.offAny(fn)
     })
 
     it('should send a value', () => {
@@ -118,6 +260,7 @@ describe('kefir-test-utils', () => {
       const obs = activate(stream())
 
       expect(obs._active).to.equal(true)
+      deactivate(obs)
     })
 
     it('should deactivate an activated observable', () => {