add jasmine tests to verify link rewriting in HTML editor

common/lib/xmodule/xmodule/js/fixtures/html-edit-with-links.html

+<section class="html-edit">
+    <ul class="editor-tabs">
+        <li><a href="#" class="visual-tab tab current" data-tab="visual">Visual</a></li>
+        <li><a href="#" class="html-tab tab" data-tab="advanced">HTML</a></li>
+    </ul>
+    <div class="row">
+        <textarea class="tiny-mce">dummy text</textarea>
+        <textarea name="" class="edit-box">Advanced Editor Text with link /static/dummy.jpg</textarea>
+    </div>
+</section>
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common/lib/xmodule/xmodule/js/spec/html/edit_spec.coffee

@@ -48,6 +48,16 @@ describe 'HTMLEditingDescriptor', ->
       expect(@descriptor.showingVisualEditor).toEqual(true)
       data = @descriptor.save().data
       expect(data).toEqual('from visual editor')
+    it 'Performs link rewriting for static assets when saving', ->
+      visualEditorStub =
+        isDirty: () -> true
+        getContent: () -> 'from visual editor with /c4x/foo/bar/asset/image.jpg'
+      spyOn(@descriptor, 'getVisualEditor').andCallFake () ->
+        visualEditorStub
+      expect(@descriptor.showingVisualEditor).toEqual(true)
+      @descriptor.base_asset_url = '/c4x/foo/bar/asset/'
+      data = @descriptor.save().data
+      expect(data).toEqual('from visual editor with /static/image.jpg')
   describe 'Can switch to Advanced Editor', ->
     beforeEach ->
       loadFixtures 'html-edit.html'
@@ -88,3 +98,23 @@ describe 'HTMLEditingDescriptor', ->
       expect(visualEditorStub.isDirty()).toEqual(false)
       expect(visualEditorStub.getContent()).toEqual('Advanced Editor Text')
       expect(visualEditorStub.startContent).toEqual('Advanced Editor Text')
+    it 'When switching to Advanced Editors links are rewritten to c4x format', ->
+      loadFixtures 'html-edit-with-links.html'
+      @descriptor = new HTMLEditingDescriptor($('.html-edit'))
+      @descriptor.base_asset_url = '/c4x/foo/bar/asset/'
+      @descriptor.showingVisualEditor = false
+
+      visualEditorStub =
+        isNotDirty: false
+        content: 'not set'
+        startContent: 'not set',
+        focus: () -> true
+        isDirty: () -> not @isNotDirty
+        setContent: (x) -> @content = x
+        getContent: -> @content
+
+      @descriptor.showVisualEditor(visualEditorStub)
+      expect(@descriptor.showingVisualEditor).toEqual(true)
+      expect(visualEditorStub.isDirty()).toEqual(false)
+      expect(visualEditorStub.getContent()).toEqual('Advanced Editor Text with link /c4x/foo/bar/asset/dummy.jpg')
+      expect(visualEditorStub.startContent).toEqual('Advanced Editor Text with link /c4x/foo/bar/asset/dummy.jpg')
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