feat(BehaviorSubject): now throws when getValue is called after unsub…

…scription

related #758

spec/subjects/behavior-subject-spec.js

@@ -4,6 +4,7 @@ var Rx = require('../../dist/cjs/Rx');
 var BehaviorSubject = Rx.BehaviorSubject;
 var nextTick = Rx.Scheduler.nextTick;
 var Observable = Rx.Observable;
+var ObjectUnsubscribedError = Rx.ObjectUnsubscribedError;
 
 describe('BehaviorSubject', function () {
   it('should extend Subject', function (done) {
@@ -12,6 +13,23 @@ describe('BehaviorSubject', function () {
     done();
   });
 
+  it('should throw if it has received an error and getValue() is called', function () {
+    var subject = new BehaviorSubject(null);
+    subject.error(new Error('derp'));
+    expect(function () {
+      subject.getValue();
+    }).toThrow(new Error('derp'));
+  });
+
+  it('should throw an ObjectUnsubscribedError if getValue() is called ' +
+    'and the BehaviorSubject has been unsubscribed', function () {
+      var subject = new BehaviorSubject('hi there');
+      subject.unsubscribe();
+      expect(function () {
+        subject.getValue();
+      }).toThrow(new ObjectUnsubscribedError());
+    });
+
   it('should have a getValue() method to retrieve the current value', function () {
     var subject = new BehaviorSubject('staltz');
     expect(subject.getValue()).toBe('staltz');

src/subject/BehaviorSubject.ts

@@ -1,18 +1,29 @@
 import {Subject} from '../Subject';
 import {Subscriber} from '../Subscriber';
 import {Subscription} from '../Subscription';
+import {throwError} from '../util/throwError';
+import {ObjectUnsubscribedError} from '../util/ObjectUnsubscribedError';
 
 export class BehaviorSubject<T> extends Subject<T> {
+  private _hasError: boolean = false;
+  private _err: any;
+
   constructor(private _value: T) {
     super();
   }
 
   getValue(): T {
-    return this._value;
+    if (this._hasError) {
+      throwError(this._err);
+    } else if (this.isUnsubscribed) {
+      throwError(new ObjectUnsubscribedError());
+    } else {
+      return this._value;
+    }
   }
 
   get value(): T {
-    return this._value;
+    return this.getValue();
   }
 
   _subscribe(subscriber: Subscriber<any>): Subscription<T> {
@@ -28,4 +39,9 @@ export class BehaviorSubject<T> extends Subject<T> {
   _next(value: T): void {
     super._next(this._value = value);
   }
+
+  _error(err: any): void {
+    this._hasError = true;
+    super._error(this._err = err);
+  }
 }