Bug 836599 - Part 14: Run most of the existing Web Audio tests using OfflineAudioContext as well as AudioContext; r=roc

This helps us get a decent amount of test coverage on OfflineAudioContext in
both the existing tests and the future tests.

content/media/webaudio/test/webaudio.js

@@ -31,8 +31,11 @@ function compareBuffers(buf1, buf2,
                         /*optional*/ offset,
                         /*optional*/ length,
                         /*optional*/ sourceOffset,
-                        /*optional*/ destOffset) {
-  is(buf1.length, buf2.length, "Buffers must have the same length");
+                        /*optional*/ destOffset,
+                        /*optional*/ skipLengthCheck) {
+  if (!skipLengthCheck) {
+    is(buf1.length, buf2.length, "Buffers must have the same length");
+  }
   if (length == undefined) {
     length = buf1.length - (offset || 0);
   }
@@ -100,48 +103,89 @@ function runTest()
       gTest.numberOfChannels = 2; // default
     }
 
-    var context = new AudioContext();
-    if (!gTest.createExpectedBuffers) {
-      // Assume that the output is silence
-      var expectedBuffers = getEmptyBuffer(context, gTest.length);
-    } else {
-      var expectedBuffers = gTest.createExpectedBuffers(context);
-    }
-    if (!(expectedBuffers instanceof Array)) {
-      expectedBuffers = [expectedBuffers];
-    }
-    var expectedFrames = 0;
-    for (var i = 0; i < expectedBuffers.length; ++i) {
-      is(expectedBuffers[i].numberOfChannels, gTest.numberOfChannels,
-         "Correct number of channels for expected buffer " + i);
-      expectedFrames += expectedBuffers[i].length;
-    }
-    is(expectedFrames, gTest.length, "Correct number of expected frames");
+    var testLength;
 
-    if (gTest.createGraphAsync) {
-      gTest.createGraphAsync(context, function(nodeToInspect) {
-        testOutput(nodeToInspect);
-      });
-    } else {
-      testOutput(gTest.createGraph(context));
+    function runTestOnContext(context, callback, testOutput) {
+      if (!gTest.createExpectedBuffers) {
+        // Assume that the output is silence
+        var expectedBuffers = getEmptyBuffer(context, gTest.length);
+      } else {
+        var expectedBuffers = gTest.createExpectedBuffers(context);
+      }
+      if (!(expectedBuffers instanceof Array)) {
+        expectedBuffers = [expectedBuffers];
+      }
+      var expectedFrames = 0;
+      for (var i = 0; i < expectedBuffers.length; ++i) {
+        is(expectedBuffers[i].numberOfChannels, gTest.numberOfChannels,
+           "Correct number of channels for expected buffer " + i);
+        expectedFrames += expectedBuffers[i].length;
+      }
+      is(expectedFrames, gTest.length, "Correct number of expected frames");
+
+      if (gTest.createGraphAsync) {
+        gTest.createGraphAsync(context, function(nodeToInspect) {
+          testOutput(nodeToInspect, expectedBuffers, callback);
+        });
+      } else {
+        testOutput(gTest.createGraph(context), expectedBuffers, callback);
+      }
     }
 
-    function testOutput(nodeToInspect) {
-      var sp = context.createScriptProcessor(expectedBuffers[0].length, gTest.numberOfChannels);
-      nodeToInspect.connect(sp);
-      sp.connect(context.destination);
-      sp.onaudioprocess = function(e) {
-        var expectedBuffer = expectedBuffers.shift();
-        is(e.inputBuffer.numberOfChannels, expectedBuffer.numberOfChannels,
-           "Correct number of input buffer channels");
-        for (var i = 0; i < e.inputBuffer.numberOfChannels; ++i) {
-          compareBuffers(e.inputBuffer.getChannelData(i), expectedBuffer.getChannelData(i));
-        }
-        if (expectedBuffers.length == 0) {
-          sp.onaudioprocess = null;
-          done();
-        }
-      };
+    function testOnNormalContext(callback) {
+      function testOutput(nodeToInspect, expectedBuffers, callback) {
+        testLength = 0;
+        var sp = context.createScriptProcessor(expectedBuffers[0].length, gTest.numberOfChannels);
+        nodeToInspect.connect(sp);
+        sp.connect(context.destination);
+        sp.onaudioprocess = function(e) {
+          var expectedBuffer = expectedBuffers.shift();
+          testLength += expectedBuffer.length;
+          is(e.inputBuffer.numberOfChannels, expectedBuffer.numberOfChannels,
+             "Correct number of input buffer channels");
+          for (var i = 0; i < e.inputBuffer.numberOfChannels; ++i) {
+            compareBuffers(e.inputBuffer.getChannelData(i), expectedBuffer.getChannelData(i));
+          }
+          if (expectedBuffers.length == 0) {
+            sp.onaudioprocess = null;
+            callback();
+          }
+        };
+      }
+      var context = new AudioContext();
+      runTestOnContext(context, callback, testOutput);
     }
+
+    function testOnOfflineContext(callback) {
+      function testOutput(nodeToInspect, expectedBuffers, callback) {
+        nodeToInspect.connect(context.destination);
+        context.oncomplete = function(e) {
+          var samplesSeen = 0;
+          while (expectedBuffers.length) {
+            var expectedBuffer = expectedBuffers.shift();
+            is(e.renderedBuffer.numberOfChannels, expectedBuffer.numberOfChannels,
+               "Correct number of input buffer channels");
+            for (var i = 0; i < e.renderedBuffer.numberOfChannels; ++i) {
+              compareBuffers(e.renderedBuffer.getChannelData(i),
+                             expectedBuffer.getChannelData(i),
+                             undefined,
+                             expectedBuffer.length,
+                             samplesSeen,
+                             undefined,
+                             true);
+            }
+            samplesSeen += expectedBuffer.length;
+          }
+          callback();
+        };
+        context.startRendering();
+      }
+      var context = new OfflineAudioContext(gTest.numberOfChannels, testLength, 48000);
+      runTestOnContext(context, callback, testOutput);
+    }
+
+    testOnNormalContext(function() {
+      testOnOfflineContext(done);
+    });
   });
 }