MediaPerceptionPrivate API impl and testing.

chrome/test/data/extensions/api_test/media_perception_private/media_perception/runtest.js

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Set the state to STARTED to automatically start listening to
+// MediaPerceptionDetection signals.
+
+function registerListener() {
+  chrome.test.listenOnce(
+      chrome.mediaPerceptionPrivate.onMediaPerception,

[tbarzic, 2017/05/09 01:28:36]

setState directly causing an event to be dispathed seems to automagical :)

I'd do something like:

chrome.test.runTests([
  // the first subtest is probably not required 
  function runMediaPerceptionServiceTest() {
    chrome.mediaPerceptionPrivate.setState({
      status: 'RUNNING'
    }, chrome.test.callbackPass(function(response) {
      chrome.test.assertEq(response, {status: 'RUNNING'});
    })));
  },
  function mediaPerceptionListenerTest() {
    chrome.test.listenOnce(
        chrome.mediaPeceptionPrivate.onMediaPerception,
        function(evt) {
          chrome.test.assertEq(evt.timestamp, 1);
        });

     chrome.test.sendMessage('mediaPerceptionListenerSet');
     // in C++ test would wait for mediaPerceptionListenerSet message, and
invoke a method on
     // fake client to trigger a fake mediaPerception signal
     // this is a little more work, but it makes the test flow clearer, and more
future prone
  }
])

[Luke Sorenson, 2017/05/09 21:05:44]

Done.

+      function(evt) {
+        chrome.test.assertEq(evt.timestamp, 1);
+    });
+  let kStatusEnum = "RUNNING";
+  chrome.mediaPerceptionPrivate.setState(
+     { status: kStatusEnum }, chrome.test.callbackPass(
+         function (response) {
+           chrome.test.assertEq(response.status, kStatusEnum);
+     }));
+}
+
+// By calling setState, we trigger the fake D-Bus client to fire an
+// onMediaPerception event.
+chrome.test.runTests([registerListener]);
+