Commit 0cf67e92

@@ -0,0 +1,22 @@
+function Player() {
+}
+Player.prototype.play = function(song) {
+  this.currentlyPlayingSong = song;
+  this.isPlaying = true;
+};
+
+Player.prototype.pause = function() {
+  this.isPlaying = false;
+};
+
+Player.prototype.resume = function() {
+  if (this.isPlaying) {
+    throw new Error("song is already playing");
+  }
+
+  this.isPlaying = true;
+};
+
+Player.prototype.makeFavorite = function() {
+  this.currentlyPlayingSong.persistFavoriteStatus(true);
+};
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@@ -0,0 +1,7 @@
+function Song() {
+}
+
+Song.prototype.persistFavoriteStatus = function(value) {
+  // something complicated
+  throw new Error("not yet implemented");
+};
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@@ -0,0 +1,9 @@
+beforeEach(function() {
+  this.addMatchers({
+    toBePlaying: function(expectedSong) {
+      var player = this.actual;
+      return player.currentlyPlayingSong === expectedSong
+          && player.isPlaying;
+    }
+  })
+});

@@ -0,0 +1,58 @@
+describe("Player", function() {
+  var player;
+  var song;
+
+  beforeEach(function() {
+    player = new Player();
+    song = new Song();
+  });
+
+  it("should be able to play a Song", function() {
+    player.play(song);
+    expect(player.currentlyPlayingSong).toEqual(song);
+
+    //demonstrates use of custom matcher
+    expect(player).toBePlaying(song);
+  });
+
+  describe("when song has been paused", function() {
+    beforeEach(function() {
+      player.play(song);
+      player.pause();
+    });
+
+    it("should indicate that the song is currently paused", function() {
+      expect(player.isPlaying).toBeFalsy();
+
+      // demonstrates use of 'not' with a custom matcher
+      expect(player).not.toBePlaying(song);
+    });
+
+    it("should be possible to resume", function() {
+      player.resume();
+      expect(player.isPlaying).toBeTruthy();
+      expect(player.currentlyPlayingSong).toEqual(song);
+    });
+  });
+
+  // demonstrates use of spies to intercept and test method calls
+  it("tells the current song if the user has made it a favorite", function() {
+    spyOn(song, 'persistFavoriteStatus');
+
+    player.play(song);
+    player.makeFavorite();
+
+    expect(song.persistFavoriteStatus).toHaveBeenCalledWith(true);
+  });
+
+  //demonstrates use of expected exceptions
+  describe("#resume", function() {
+    it("should throw an exception if song is already playing", function() {
+      player.play(song);
+
+      expect(function() {
+        player.resume();
+      }).toThrow("song is already playing");
+    });
+  });
+});
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