Add spec for dragging/dropping tabs across editors

src/app/editor.coffee

@@ -550,11 +550,19 @@ class Editor extends View
     )
 
   moveEditSessionAtIndex: (fromIndex, toIndex) ->
+    return if fromIndex is toIndex
     editSession = @editSessions.splice(fromIndex, 1)
     @editSessions.splice(toIndex, 0, editSession[0])
     @trigger 'editor:edit-session-order-changed', [editSession, fromIndex, toIndex]
     @setActiveEditSessionIndex(toIndex)
 
+  moveEditSessionToEditor: (fromIndex, toEditor, toIndex) ->
+    fromEditSession = @editSessions[fromIndex]
+    toEditSession = fromEditSession.copy()
+    @destroyEditSessionIndex(fromIndex)
+    toEditor.edit(toEditSession)
+    toEditor.moveEditSessionAtIndex(toEditor.getActiveEditSessionIndex(), toIndex)
+
   transferEditSessionAtIndex: (fromIndex, toIndex, toEditor) ->
     toEditor.editSessions.splice(toIndex, 0, @editSessions.splice(fromIndex, 1)[0])
 

src/packages/tabs/lib/tab-view.coffee

@@ -70,6 +70,7 @@ class TabView extends SortableList
   onDrop: (event) =>
     super
 
+    droppedNearTab = @getSortableElement(event)
     transfer = event.originalEvent.dataTransfer
     previousDraggedTabIndex = transfer.getData 'sortable-index'
 
@@ -77,36 +78,21 @@ class TabView extends SortableList
     toPaneIndex   = rootView.indexOfPane($(event.target).closest('.pane'))
     fromPane      = $(rootView.find('.pane')[fromPaneIndex])
     fromEditor    = fromPane.find('.editor').view()
+    draggedTab    = fromPane.find(".#{TabView.viewClass()} .sortable:eq(#{previousDraggedTabIndex})")
+    return if draggedTab.is(droppedNearTab)
 
     if fromPaneIndex == toPaneIndex
       droppedNearTab = @getSortableElement(event)
-      draggedTab = fromPane.find(".#{TabView.viewClass()} .sortable:eq(#{previousDraggedTabIndex})")
-      unless draggedTab.is(droppedNearTab)
-        fromIndex = draggedTab.index()
-        toIndex = droppedNearTab.index()
-        toIndex++ if fromIndex > toIndex
-        fromEditor.moveEditSessionAtIndex(fromIndex, toIndex)
+      fromIndex = draggedTab.index()
+      toIndex = droppedNearTab.index()
+      toIndex++ if fromIndex > toIndex
+      fromEditor.moveEditSessionAtIndex(fromIndex, toIndex)
     else
       toPane = $(rootView.find('.pane')[toPaneIndex])
       toEditor = toPane.find('.editor').view()
 
-      droppedNearTab = @getSortableElement(event)
-      draggedTab     = fromPane.find(".#{TabView.viewClass()} .sortable:eq(#{previousDraggedTabIndex})")
-
-      return if draggedTab.is(droppedNearTab)
       if fromPaneIndex != toPaneIndex
         return if @containsEditSession(toEditor, fromEditor.editSessions[draggedTab.index()])
 
-      draggedTab.remove()
-      draggedTab.insertAfter(droppedNearTab)
-      currentDraggedTabIndex = draggedTab.index()
-      fromEditor.transferEditSessionAtIndex(previousDraggedTabIndex, currentDraggedTabIndex, toEditor)
-
-      if !fromPane.find('.tab').length
-        fromPane.view().remove()
-      else if fromPaneIndex != toPaneIndex && draggedTab.hasClass('active')
-        fromEditor.setActiveEditSessionIndex(0)
-
-      @setActiveTab(currentDraggedTabIndex)
-      toEditor.setActiveEditSessionIndex(currentDraggedTabIndex)
+      fromEditor.moveEditSessionToEditor(draggedTab.index(), toEditor, droppedNearTab.index() + 1)
       toEditor.focus()

src/packages/tabs/spec/tabs-spec.coffee

@@ -180,3 +180,28 @@ describe "TabView", ->
 
         expect(tabs.find('.tab:eq(0) .file-name').text()).toBe "sample.txt"
         expect(tabs.find('.tab:eq(1) .file-name').text()).toBe "sample.js"
+
+    describe "when a tab is dragged from one editor and dropped onto another editor", ->
+      it "moves the edit session and updates the order of the tabs", ->
+        leftTabs = tabs
+        editor.splitRight()
+        rightTabs = rootView.find('.tabs:last').view()
+
+        sortableElement = [leftTabs.find('.tab:eq(0)')]
+        spyOn(tabs, 'getSortableElement').andCallFake -> sortableElement[0]
+        event = $.Event()
+        event.target = leftTabs
+        event.originalEvent =
+          dataTransfer:
+            data: {}
+            setData: (key, value) -> @data[key] = value
+            getData: (key) -> @data[key]
+
+        tabs.onDragStart(event)
+
+        event.target = rightTabs
+        sortableElement = [rightTabs.find('.tab:eq(0)')]
+        tabs.onDrop(event)
+
+        expect(rightTabs.find('.tab:eq(0) .file-name').text()).toBe "sample.txt"
+        expect(rightTabs.find('.tab:eq(1) .file-name').text()).toBe "sample.js"