diff --git a/spec/operators/switchMapTo-spec.js b/spec/operators/switchMapTo-spec.js
new file mode 100644
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+++ b/spec/operators/switchMapTo-spec.js
@@ -0,0 +1,187 @@
+/* globals describe, it, expect, cold, hot, expectObservable, expectSubscriptions */
+var Rx = require('../../dist/cjs/Rx');
+var Observable = Rx.Observable;
+var immediateScheduler = Rx.Scheduler.immediate;
+
+describe('Observable.prototype.switchMapTo()', function () {
+  it('should switch a synchronous many outer to a synchronous many inner', function (done) {
+    var a = Observable.of(1, 2, 3);
+    var expected = ['a', 'b', 'c', 'a', 'b', 'c', 'a', 'b', 'c'];
+    a.switchMapTo(Observable.of('a', 'b', 'c')).subscribe(function (x) {
+      expect(x).toBe(expected.shift());
+    }, null, done);
+  });
+
+  it('should unsub inner observables', function () {
+    var unsubbed = 0;
+
+    Observable.of('a', 'b').switchMapTo(
+      Observable.create(function (subscriber) {
+        subscriber.complete();
+        return function () {
+          unsubbed++;
+        };
+      })
+    ).subscribe();
+
+    expect(unsubbed).toEqual(2);
+  });
+
+  it('should switch to an inner cold observable', function () {
+    var x =   cold(         '--a--b--c--d--e--|          ');
+    var xsubs =   ['         ^         !                 ',
+    //                                 --a--b--c--d--e--|
+                   '                   ^                !'];
+    var e1 =   hot('---------x---------x---------|       ');
+    var expected = '-----------a--b--c---a--b--c--d--e--|';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner cold observable, outer eventually throws', function () {
+    var x =   cold(         '--a--b--c--d--e--|');
+    var xsubs =    '         ^         !';
+    var e1 =   hot('---------x---------#');
+    var expected = '-----------a--b--c-#';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner cold observable, outer is unsubscribed early', function () {
+    var x =   cold(         '--a--b--c--d--e--|   ');
+    var xsubs =   ['         ^         !          ',
+    //                                 --a--b--c--d--e--|
+                   '                   ^  !       '];
+    var e1 =   hot('---------x---------x---------|');
+    var unsub =    '                      !       ';
+    var expected = '-----------a--b--c---a-       ';
+
+    expectObservable(e1.switchMapTo(x), unsub).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner cold observable, inner never completes', function () {
+    var x =   cold(         '--a--b--c--d--e-          ');
+    var xsubs =   ['         ^         !               ',
+    //                                 --a--b--c--d--e-
+                   '                   ^               '];
+    var e1 =   hot('---------x---------y---------|');
+    var expected = '-----------a--b--c---a--b--c--d--e-';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should handle a synchronous switch to the inner observable', function () {
+    var x =   cold(         '--a--b--c--d--e--|   ');
+    var xsubs =   ['         (^!)                 ',
+                   '         ^                !   '];
+    var e1 =   hot('---------(xx)----------------|');
+    var expected = '-----------a--b--c--d--e-----|';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner cold observable, inner raises an error', function () {
+    var x =   cold(         '--a--b--#');
+    var xsubs =    '         ^       !';
+    var e1 =   hot('---------x---------x---------|');
+    var expected = '-----------a--b--#';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch an inner hot observable', function () {
+    var x =    hot('--p-o-o-p---a--b--c--d-|      ');
+    var xsubs =   ['         ^         !          ',
+                   '                   ^   !      '];
+    var e1 =   hot('---------x---------x---------|');
+    var expected = '------------a--b--c--d-------|';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner empty', function () {
+    var x = cold('|');
+    var xsubs =   ['         (^!)                 ',
+                   '                   (^!)       '];
+    var e1 =   hot('---------x---------x---------|');
+    var expected = '-----------------------------|';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner never', function () {
+    var x = cold('-');
+    var xsubs =   ['         ^         !           ',
+                   '                   ^           '];
+    var e1 =   hot('---------x---------x---------|');
+    var expected = '----------------------------------';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should switch to an inner that just raises an error', function () {
+    var x = cold('#');
+    var xsubs =    '         (^!)';
+    var e1 =   hot('---------x---------x---------|');
+    var expected = '---------#';
+
+    expectObservable(e1.switchMapTo(x)).toBe(expected);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+
+  it('should handle an empty outer', function () {
+    var e1 = cold( '|');
+    var expected = '|';
+
+    expectObservable(e1.switchMapTo(Observable.of('foo'))).toBe(expected);
+  });
+
+  it('should handle a never outer', function () {
+    var e1 = cold( '-');
+    var expected = '-';
+
+    expectObservable(e1.switchMapTo(Observable.of('foo'))).toBe(expected);
+  });
+
+  it('should handle an outer that just raises and error', function () {
+    var e1 = cold( '#');
+    var expected = '#';
+
+    expectObservable(e1.switchMapTo(Observable.of('foo'))).toBe(expected);
+  });
+
+  it('should switch with resultSelector goodness', function () {
+    var x =   cold(         '--1--2--3--4--5--|          ');
+    var xsubs =   ['         ^         !                 ',
+    //                                 --1--2--3--4--5--|
+                   '                   ^                !'];
+    var e1 =   hot('---------x---------y---------|       ');
+    var expected = '-----------a--b--c---d--e--f--g--h--|';
+    var expectedValues = {
+      a: ['x', '1', 0, 0],
+      b: ['x', '2', 0, 1],
+      c: ['x', '3', 0, 2],
+      d: ['y', '1', 1, 0],
+      e: ['y', '2', 1, 1],
+      f: ['y', '3', 1, 2],
+      g: ['y', '4', 1, 3],
+      h: ['y', '5', 1, 4]
+    };
+
+    var result = e1.switchMapTo(x, function (a, b, ai, bi) {
+      return [a, b, ai, bi];
+    });
+
+    expectObservable(result).toBe(expected, expectedValues);
+    expectSubscriptions(x.subscriptions).toBe(xsubs);
+  });
+});
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