Fix AudioNode.disconnect() to support selective disconnection.

LayoutTests/webaudio/resources/audio-testing.js

 if (window.testRunner)
     testRunner.overridePreference("WebKitWebAudioEnabled", "1");
 
 function writeString(s, a, offset) {
     for (var i = 0; i < s.length; ++i) {
         a[offset + i] = s.charCodeAt(i);
     }
 }
 
 function writeInt16(n, a, offset) {
@@ skipping 157 matching lines @@
     var endFrame = timeToSampleFrame(grainOffset + duration, sampleRate);
 
     return endFrame - startFrame;
 }
 
 // True if the number is not an infinity or NaN
 function isValidNumber(x) {
     return !isNaN(x) && (x != Infinity) && (x != -Infinity);
 }
 
-function shouldThrowTypeError(func, text) {

[Raymond Toy, 2015/02/11 21:31:18]

No test was using this function?

[hongchan, 2015/02/12 18:38:00]

This is removed and merged into |Should| name space.

-    var ok = false;
-    try {
-        func();
-    } catch (e) {
-        if (e instanceof TypeError) {
-            ok = true;
-        }
-    }
-    if (ok) {
-        testPassed(text + " threw TypeError.");
-    } else {
-        testFailed(text + " should throw TypeError.");
-    }
-}
-
 // |Audit| is a task runner for web audio test. It makes asynchronous web audio
 // testing simple and manageable.
 //
 // EXAMPLE:
 //
 //   var audit = Audit.createTaskRunner();
 //   // Define test routine. Make sure to call done() when reached at the end.
 //   audit.defineTask('foo', function (done) {
 //     var context = new AudioContext();
 //     // do things
@@ skipping 44 matching lines @@
         // Start task 0.
         this.tasks[this.queue[this.currentTask]](done);
     };
 
     return {
         createTaskRunner: function () {
             return new Tasks();
         }
     };
 
-})();
+})();
+
+
+// Create a channel buffer for testing. Push a channel index value into the
+// each channel buffer. The channel index is between 1 and |numChannels|.
+// For example, a 4 channel buffer will have values [1, 2, 3, 4] for each
+// channel respectively.

[Raymond Toy, 2015/02/11 21:31:18]

I think I'd rephrase this. We're not really pushing anything right?  Also add
comment that each channel has a constant value.

[hongchan, 2015/02/12 18:38:00]

Done.

+function createTestingBuffer(context, numChannels, length) {
+    var buffer = context.createBuffer(numChannels, length, context.sampleRate);
+    for (var i = 1; i <= numChannels; i++) {
+        var data = buffer.getChannelData(i-1);
+        for (var j = 0; j < data.length; j++) {
+            // Storing channel index into the channel buffer.
+            data[j] = i;
+        }
+    }
+    return buffer;
+}
+
+// Get summarized (truncated) function content.

[Raymond Toy, 2015/02/11 21:31:18]

I have no idea what this function is trying to do from reading this comment and
the code.  Please clarify.

[hongchan, 2015/02/12 18:38:00]

I missed that. Will add comment here. This is basically to provide the summary
of task by concatenating first few letters of function argument. It certainly
can be improved.

+function getTaskSummary(func) {
+    var content = func.toString().replace(/(\s|\t|\r\n|\n|\r)/gm, '');
+    return '"' + content.slice(11, 30) + '..."';
+}
+
+
+// |Should| test utilities. Note that testPassed(), testFailed() are from
+// resources/js-test.js.
+var Should = {};
+
+// Expect exception with a certin type. If type is undefined, it only checks for
+// the exception.
+Should.throwWithType = function (func, type) {
+    try {
+        func();
+        var content = Expect.getTaskSummary(func);
+        testFailed('Exception should be thrown from '+ content);
+    } catch (e) {
+        if (e.name === type || type === undefined)
+            testPassed(e.name + ' was thrown as expected.');
+        else
+            testFailed('Expected ' + type + ' but got ' + e.name);

[Raymond Toy, 2015/02/11 21:31:18]

I didn't check, but it would be nice if you kind of followed the existing
shouldThrow messages from js-test.js.

[hongchan, 2015/02/12 18:38:00]

Good idea. Done.

+    }
+};
+
+// Expect not to throw an exception.
+Should.notThrow = function (func) {
+    try {
+        func();
+        testPassed('Error was not thrown as expected.');
+    } catch (e) {
+        var content = Expect.getFunctionContent(func);
+        testFailed('Error was not expected but got ' + e.name + ' from ' + content);
+    }
+};
+
+
+// Expect the channelData to have a certain value.

[Raymond Toy, 2015/02/11 21:31:18]

Expand this comment to say that every value in channelData is the constant
|value|.

[hongchan, 2015/02/12 18:38:00]

Done.

+Should.haveValueInChannel = function (value, channelData) {
+    var flag = true;

[Raymond Toy, 2015/02/11 21:31:18]

s/flag/isConstant/ or some other more meaningful name.

[hongchan, 2015/02/12 18:38:00]

Done.

+    for (var i = 0; i < channelData.length; i++) {
+        if (channelData[i] !== value) {
+            flag = false;
+            break;
+        }
+    }
+    if (flag)
+        testPassed('ChannelData has expected values.');

[Raymond Toy, 2015/02/11 21:31:18]

Include the expected value in message.

[hongchan, 2015/02/12 18:38:00]

Done.

+    else
+        testFailed('ChannelData has invalid values (expected ' + value + ')');

[Raymond Toy, 2015/02/11 21:31:18]

Might be useful for debugging to include the index and the bad value.

In fact, it might be useful to print out all of the bad values (up to some small
limit).

[hongchan, 2015/02/12 18:38:00]

Yes, I will come up with a way of doing this.

+};