DevTools: Add test for SourceCodeDiff

third_party/WebKit/Source/devtools/front_end/sources/SourceCodeDiff.js

 // Copyright 2016 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.
 
 /**
  * @constructor
  * @param {!Promise<?string>} diffBaseline
  * @param {!WebInspector.CodeMirrorTextEditor} textEditor
  */
 WebInspector.SourceCodeDiff = function(diffBaseline, textEditor)
@@ skipping 206 matching lines @@
             var diffEntry = diff[i];
             for (var lineNumber = diffEntry.from; lineNumber < diffEntry.to; ++lineNumber)
                 newDecorations.set(lineNumber, {lineNumber: lineNumber, type: diffEntry.type});
         }
 
         var decorationDiff = oldDecorations.diff(newDecorations, (e1, e2) => e1.type === e2.type);
         var addedDecorations = decorationDiff.added.map(entry => new WebInspector.SourceCodeDiff.GutterDecoration(this._textEditor, entry.lineNumber, entry.type));
 
         this._decorations = decorationDiff.equal.concat(addedDecorations);
         this._updateDecorations(decorationDiff.removed, addedDecorations);
+        this._decorationsSetForTest(newDecorations);
     },
+
+    /**
+     * @param {!Map<number, !{lineNumber: number, type: !WebInspector.SourceCodeDiff.GutterDecorationType}>} decorations
+     */
+    _decorationsSetForTest: function(decorations) { }
 }
 
 /** @enum {string} */
 WebInspector.SourceCodeDiff.GutterDecorationType = {
     Insert: "Insert",
     Delete: "Delete",
     Modify: "Modify",
 }
 
 /**
@@ skipping 41 matching lines @@
 
     remove: function()
     {
         var location = this._position.resolve();
         if (!location)
             return;
         this._textEditor.setGutterDecoration(location.lineNumber, WebInspector.SourceCodeDiff.DiffGutterType, null);
         this._textEditor.toggleLineClass(location.lineNumber, this._className, false);
     }
 }