Add Polymer tests for cr-settings-prefs

chrome/test/data/webui/settings/prefs_tests.js

Index: chrome/test/data/webui/settings/prefs_tests.js
diff --git a/chrome/test/data/webui/settings/prefs_tests.js b/chrome/test/data/webui/settings/prefs_tests.js
new file mode 100644
index 0000000000000000000000000000000000000000..b6272aec047c934b9ea7de76dab30b1acd64491e
--- /dev/null
+++ b/chrome/test/data/webui/settings/prefs_tests.js
@@ -0,0 +1,291 @@
+// Copyright 2015 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.
+
+/** @fileoverview Suite of tests for cr-settings-prefs. */
+cr.define('cr_settings_prefs', function() {
+  /**
+   * Mock of chrome.settingsPrivate API.
+   * @constructor
+   * @extends {chrome.settingsPrivate}
+   */
+  function MockSettingsApi() {
+    this.prefs = {};
+    this.listener_ = null;
+
+    // Hack alert: bind this instance's onPrefsChanged members to this.
+    this.onPrefsChanged = {
+      addListener: this.onPrefsChanged.addListener.bind(this),
+      removeListener: this.onPrefsChanged.removeListener.bind(this),
+    };
+
+    this.addBooleanPref_('top_level_pref', true);
+    this.addBooleanPref_('browser.enable_flash', false);
+    this.addBooleanPref_('browser.enable_html5', true);
+    this.addNumberPref_('device.overclock', .6);
+    this.addStringPref_('homepage', 'example.com');
+  }
+
+  MockSettingsApi.prototype = {
+    // chrome.settingsPrivate overrides.
+    onPrefsChanged: {
+      addListener: function(listener) {
+        this.listener_ = listener;
+      },
+
+      removeListener: function(listener) {
+        expectNotEquals(null, this.listener_);
+        this.listener_ = null;
+      },
+    },
+
+    getAllPrefs: function(callback) {
+      // Send a copy of prefs to keep our internal state private.
+      var prefs = [];
+      for (var key in this.prefs)
+        prefs.push(Object.assign({}, this.prefs[key]));
+
+      setTimeout(callback.bind(null, prefs));
+    },
+
+    setPref: function(key, value, pageId, callback) {
+      var pref = this.prefs[key];
+      assertNotEquals(undefined, pref);
+      assertEquals(typeof value, typeof pref.value);
+      assertEquals(Array.isArray(value), Array.isArray(pref.value));
+
+      if (this.failNextSetPref_) {
+        setTimeout(callback.bind(null, false));
+        this.failNextSetPref_ = false;
+        return;
+      }
+
+      // TODO(michaelpg): support list and dict prefs.
+      var changed = this.prefs[key].value != value;
+      this.prefs[key].value = value;
+      setTimeout(function() {
+        callback(true);
+        // Like chrome.settingsPrivate, send a notification when prefs change.
+        if (changed)
+          this.sendPrefChanges([key], [value]);
+      }.bind(this));
+    },
+
+    getPref: function(key, callback) {
+      var pref = this.prefs[key];
+      assertNotEquals(undefined, pref);
+
+      var prefCopy = Object.assign({}, pref);
+      setTimeout(callback.bind(null, prefCopy));
+    },
+
+    // Functions used by tests.
+
+    /** Instructs the API to fail when setPref is next called. */
+    failNextSetPref: function() {
+      this.failNextSetPref_ = true;
+    },
+
+    /**
+     * Notifies the listener of pref changes.
+     * @param {!Array<string>} keys
+     * @param {!Array<*>} values
+     */
+    sendPrefChanges: function(keys, values) {
+      var prefs = [];
+      for (var i = 0; i < keys.length; i++) {
+        var key = keys[i];
+        var pref = this.prefs[key];
+        pref.value = values[i];
+        prefs.push(Object.assign({}, pref));
+      }
+
+      setTimeout(this.listener_.bind(null, prefs));
+    },
+
+    // Private methods for use by the mock API.
+
+    /**
+     * @param {!chrome.settingsPrivate.PrefType} type
+     * @param {string} key
+     * @param {*} value
+     */
+    addPref_: function(type, key, value) {
+      this.prefs[key] = {
+        type: type,
+        key: key,
+        value: value,
+      };
+    },
+
+    /**
+     * @param {string} key
+     * @param {boolean} value
+     */
+    addBooleanPref_: function(key, value) {
+      this.addPref_(chrome.settingsPrivate.PrefType.BOOLEAN, key, value);
+    },
+
+    /**
+     * @param {string} key
+     * @param {number} value
+     */
+    addNumberPref_: function(key, value) {
+      this.addPref_(chrome.settingsPrivate.PrefType.NUMBER, key, value);
+    },
+
+    /**
+     * @param {string} key
+     * @param {string} value
+     */
+    addStringPref_: function(key, value) {
+      this.addPref_(chrome.settingsPrivate.PrefType.STRING, key, value);
+    },
+  };
+
+  /**
+   * Helper function to deal with asynchronicity by repeatedly queueing
+   * tasks to check if the callback returns true.
+   * @param {function(): boolean} callback
+   * @return {Promise}
+   */
+  function waitUntilTrue(callback) {
+    return new Promise(function(resolve, reject) {
+      var interval = setInterval(function() {
+        if (callback.call()) {
+          clearInterval(interval);
+          resolve();
+        }
+      });
+    });
+  }
+
+  /**
+   * @param {!Object} prefStore Pref store from <cr-settings-prefs>.
+   * @param {string} key Pref key of the pref to return.
+   * @return {(chrome.settingsPrivate.PrefObject|undefined}

[Dan Beam, 2015/09/14 23:31:48]

nit: https://xkcd.com/859/

[michaelpg, 2015/09/15 01:17:57]

Done.

+   */
+  function getPrefFromKey(prefStore, key) {
+    var path = key.split('.');
+    var pref = prefStore;
+    for (var part of path) {
+      pref = pref[part];
+      if (!pref)
+        return;

[stevenjb, 2015/09/14 23:18:19]

nit: return undefined? (That would be more clear to me, but maybe in JS this is
a common enough pattern?)

[Dan Beam, 2015/09/14 23:31:48]

not all that common

[michaelpg, 2015/09/15 01:17:58]

Done.

+    }
+    return pref;
+  }
+
+  function registerTests() {
+    suite('CrSettingsPrefs', function() {
+      /**
+       * Prefs instance created before each test.
+       * @type {CrSettingsPrefs}
+       */
+      var prefs;
+
+      /** @type {MockSettingsApi} */
+      var mockApi = null;
+
+      // Initialize a <cr-settings-prefs> element before each test.
+      setup(function(done) {
+        mockApi = new MockSettingsApi();
+        // TODO(michaelpg): don't use global variables to inject the API.
+        window.mockApi = mockApi;
+
+        // Create and attach the <cr-settings-prefs> element.
+        PolymerTest.clearBody();
+        prefs = document.createElement('cr-settings-prefs');
+        document.body.appendChild(prefs);
+
+        window.mockApi = undefined;
+
+        // Wait for CrSettingsPrefs.INITIALIZED.
+        if (!CrSettingsPrefs.isInitialized) {
+          var listener = function() {
+            document.removeEventListener(CrSettingsPrefs.INITIALIZED, listener);
+            done();
+          };
+          document.addEventListener(CrSettingsPrefs.INITIALIZED, listener);
+          return;
+        }
+
+        done();
+      });
+
+      test('receives and caches prefs', function() {
+        // Test that each pref has been successfully copied to the Polymer
+        // |prefs| property.
+        for (var key in mockApi.prefs) {
+          var expectedPref = mockApi.prefs[key];
+          var actualPref = getPrefFromKey(prefs.prefs, key);
+          if (!expectNotEquals(undefined, actualPref)) {
+            // We've already registered an error, so skip the pref.
+            continue;
+          }
+
+          expectEquals(expectedPref.key, actualPref.key);
+          expectEquals(expectedPref.type, actualPref.type);
+          if (expectedPref.type != chrome.settingsPrivate.LIST) {
+            expectEquals(expectedPref.value, actualPref.value);
+          } else {
+            expectEquals(JSON.stringify(expectedPref.value),
+                         JSON.stringify(actualPref.value));
+          }
+        }
+      });
+
+      test('forwards pref changes to API', function() {
+        // Test that cr-settings-prefs uses the setPref API.
+        prefs.set('prefs.browser.enable_flash.value', true);
+        expectTrue(mockApi.prefs['browser.enable_flash'].value);
+
+        prefs.set('prefs.device.overclock.value', 1.2);
+        expectEquals(1.2, mockApi.prefs['device.overclock'].value);
+
+        prefs.set('prefs.homepage.value', 'chromium.org');
+        expectEquals('chromium.org', mockApi.prefs['homepage'].value);
+
+        // Test that when setPref fails, the pref is reverted locally.
+        mockApi.failNextSetPref();
+        prefs.set('prefs.browser.enable_flash.value', false);
+
+        mockApi.failNextSetPref();
+        prefs.set('prefs.device.overclock.value', 2.0);
+
+        mockApi.failNextSetPref();
+        prefs.set('prefs.homepage.value', 'invalid-url');
+
+        // Multiple asynchronous round trips need to happen.
+        return Promise.all([
+          waitUntilTrue(function() {
+            return prefs.prefs.browser.enable_flash.value;
+          }),
+          waitUntilTrue(function() {
+            return prefs.prefs.device.overclock.value == 1.2;
+          }),
+          waitUntilTrue(function() {
+            return prefs.prefs.homepage.value == 'chromium.org';
+          }),
+        ]);
+      });
+
+      test('responds to API changes', function(done) {
+        mockApi.sendPrefChanges(['top_level_pref'], [false]);
+        PolymerTest.async(function() {
+          expectEquals(false, prefs.prefs.top_level_pref.value);
+
+          mockApi.sendPrefChanges(['top_level_pref'], [true]);
+        });
+        PolymerTest.async(function() {
+          expectEquals(true, prefs.prefs.top_level_pref.value);
+          done();
+        });
+      });
+    });
+  }
+
+  return {
+    registerTests: registerTests,
+  };
+});