test(defer): add unsubscription-related tests

Add test cases for Observable.defer, to include subscription assertions and to verify it behaves
correctly when the result is unsubscribed explicitly.

Author: staltz

spec/observables/defer-spec.js

@@ -1,36 +1,45 @@
-/* globals describe, it, expect, hot, cold, expectObservable */
+/* globals describe, it, expect, hot, cold, expectObservable, expectSubscriptions */
 var Rx = require('../../dist/cjs/Rx');
 var Observable = Rx.Observable;
 
 describe('Observable.defer', function () {
   it('should create an observable from the provided observbale factory', function () {
     var source = hot('--a--b--c--|');
+    var sourceSubs = '^          !';
+    var expected =   '--a--b--c--|';
+
     var e1 = Observable.defer(function () {
       return source;
     });
-    var expected = '--a--b--c--|';
 
     expectObservable(e1).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
   });
 
   it('should create an observable from completed', function () {
     var source = hot('|');
+    var sourceSubs = '(^!)';
+    var expected =   '|';
+
     var e1 = Observable.defer(function () {
       return source;
     });
-    var expected = '|';
 
     expectObservable(e1).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
   });
 
   it('should create an observable from error', function () {
     var source = hot('#');
+    var sourceSubs = '(^!)';
+    var expected =   '#';
+
     var e1 = Observable.defer(function () {
       return source;
     });
-    var expected = '#';
 
     expectObservable(e1).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
   });
 
   it('should create an observable when factory throws', function () {
@@ -41,4 +50,33 @@ describe('Observable.defer', function () {
 
     expectObservable(e1).toBe(expected);
   });
+
+  it('should allow unsubscribing early and explicitly', function () {
+    var source = hot('--a--b--c--|');
+    var sourceSubs = '^     !     ';
+    var expected =   '--a--b-     ';
+    var unsub =      '      !     ';
+
+    var e1 = Observable.defer(function () {
+      return source;
+    });
+
+    expectObservable(e1, unsub).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
+  });
+
+  it('should not break unsubscription chains when result is unsubscribed explicitly', function () {
+    var source = hot('--a--b--c--|');
+    var sourceSubs = '^     !     ';
+    var expected =   '--a--b-     ';
+    var unsub =      '      !     ';
+
+    var e1 = Observable.defer(function () {
+      return source.mergeMap(function (x) { return Observable.of(x); });
+    })
+    .mergeMap(function (x) { return Observable.of(x); });
+
+    expectObservable(e1, unsub).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
+  });
 });