Focus and tab between diff preferences inputs

Previously, the diff preferences form did not automatically focus to the
first textfield and did not allow tabbing between input fields. This
change adds autofocus when the overlay is opened and allows for tabbing
between the other input fields in the modal.

Bug: Issue 4140
Change-Id: If15812bb4404ca4061597755eeaf68d4cae23b3f

polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.html

@@ -112,8 +112,8 @@ limitations under the License.
       </div>
     </div>
     <div class="actions">
-      <gr-button primary on-tap="_handleSave">Save</gr-button>
-      <gr-button on-tap="_handleCancel">Cancel</gr-button>
+      <gr-button id="saveButton" primary on-tap="_handleSave">Save</gr-button>
+      <gr-button id="cancelButton" on-tap="_handleCancel">Cancel</gr-button>
     </div>
   </template>
   <script src="gr-diff-preferences.js"></script>

polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.js

@@ -53,6 +53,17 @@
       '_localPrefsChanged(localPrefs.*)',
     ],
 
+    getFocusStops: function() {
+      return {
+        start: this.$.contextSelect,
+        end: this.$.cancelButton,
+      };
+    },
+
+    resetFocus: function() {
+      this.$.contextSelect.focus();
+    },
+
     _prefsChanged: function(changeRecord) {
       var prefs = changeRecord.base;
       // TODO(andybons): This is not supported in IE. Implement a polyfill.

polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences_test.html

@@ -62,6 +62,14 @@ limitations under the License.
       assert.isFalse(element._newPrefs.syntax_highlighting);
     });
 
+    test('clicking save button calls _handleSave function', function() {
+      var savePrefs = sinon.stub(element, '_handleSave');
+      MockInteractions.tap(element.$.saveButton);
+      flushAsynchronousOperations();
+      assert(savePrefs.calledOnce);
+      savePrefs.restore();
+    });
+
     test('events', function(done) {
       var savePromise = new Promise(function(resolve) {
         element.addEventListener('save', function() { resolve(); });

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html

@@ -209,6 +209,7 @@ limitations under the License.
       </div>
       <gr-overlay id="prefsOverlay" with-backdrop>
         <gr-diff-preferences
+            id="diffPreferences"
             prefs="{{_prefs}}"
             local-prefs="{{_localPrefs}}"
             on-save="_handlePrefsSave"

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js

@@ -255,7 +255,7 @@
           break;
         case 188:  // ','
           e.preventDefault();
-          this.$.prefsOverlay.open();
+          this._openPrefs();
           break;
       }
     },
@@ -267,6 +267,15 @@
       page.show(this._computeNavLinkURL(path, fileList, direction));
     },
 
+    _openPrefs: function() {
+      this.$.prefsOverlay.open().then(function() {
+        var diffPreferences = this.$.diffPreferences;
+        var focusStops = diffPreferences.getFocusStops();
+        this.$.prefsOverlay.setFocusStops(focusStops);
+        this.$.diffPreferences.resetFocus();
+      }.bind(this));
+    },
+
     /**
      * @param {?string} path The path of the current file being shown.
      * @param {Array.<string>} fileList The list of files in this change and
@@ -451,7 +460,7 @@
 
     _handlePrefsTap: function(e) {
       e.preventDefault();
-      this.$.prefsOverlay.open();
+      this._openPrefs();
     },
 
     _handlePrefsSave: function(e) {

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html

@@ -36,7 +36,7 @@ limitations under the License.
   <template>
     <div></div>
   </template>
-</text-fixture>
+</test-fixture>
 
 <script>
   suite('gr-diff-view tests', function() {
@@ -103,7 +103,9 @@ limitations under the License.
           'Should navigate to /c/42/');
       assert.equal(element.changeViewState.selectedFileIndex, 0);
 
-      var showPrefsStub = sinon.stub(element.$.prefsOverlay, 'open');
+      var showPrefsStub = sinon.stub(element.$.prefsOverlay, 'open',
+          function() { return Promise.resolve({}); });
+
       MockInteractions.pressAndReleaseKeyOn(element, 188);  // ','
       assert(showPrefsStub.calledOnce);
 
@@ -131,6 +133,26 @@ limitations under the License.
       showStub.restore();
     });
 
+    test('saving diff preferences', function() {
+      var savePrefs = sinon.stub(element, '_handlePrefsSave');
+      var cancelPrefs = sinon.stub(element, '_handlePrefsCancel');
+      element.$.diffPreferences._handleSave();
+      assert(savePrefs.calledOnce);
+      assert(cancelPrefs.notCalled);
+      savePrefs.restore();
+      cancelPrefs.restore();
+    });
+
+    test('cancelling diff preferences', function() {
+      var savePrefs = sinon.stub(element, '_handlePrefsSave');
+      var cancelPrefs = sinon.stub(element, '_handlePrefsCancel');
+      element.$.diffPreferences._handleCancel();
+      assert(cancelPrefs.calledOnce);
+      assert(savePrefs.notCalled);
+      savePrefs.restore();
+      cancelPrefs.restore();
+    });
+
     test('keyboard shortcuts with patch range', function() {
       element._changeNum = '42';
       element._patchRange = {