Intelligently activate new items when the active item is closed

If the active item was the pane's first item, the second item (which is
the new first item) is activated. Otherwise, the item to the left of the
closed item is activated.

spec/pane-spec.coffee

@@ -111,7 +111,7 @@ describe "Pane", ->
       pane = new Pane(items: [new Item("A"), new Item("B"), new Item("C")])
       [item1, item2, item3] = pane.items
 
-    it "removes the item from the items list and activates the next item if it was the active item", ->
+    it "removes the item from the items list", ->
       expect(pane.activeItem).toBe item1
       pane.destroyItem(item2)
       expect(item2 in pane.items).toBe false
@@ -119,7 +119,21 @@ describe "Pane", ->
 
       pane.destroyItem(item1)
       expect(item1 in pane.items).toBe false
-      expect(pane.activeItem).toBe item3
+
+    describe "when the destroyed item is the active item and is the first item", ->
+      it "activates the next item", ->
+        expect(pane.activeItem).toBe item1
+        pane.destroyItem(item1)
+        expect(pane.activeItem).toBe item2
+
+    describe "when the destroyed item is the active item and is not the first item", ->
+      beforeEach ->
+        pane.activateItem(item2)
+
+      it "activates the previous item", ->
+        expect(pane.activeItem).toBe item2
+        pane.destroyItem(item2)
+        expect(pane.activeItem).toBe item1
 
     it "emits 'item-removed' with the item, its index, and true indicating the item is being destroyed", ->
       pane.on 'item-removed', itemRemovedHandler = jasmine.createSpy("itemRemovedHandler")

spec/workspace-view-spec.coffee

@@ -429,23 +429,23 @@ describe "WorkspaceView", ->
       expect(workspace.getActivePaneItem().getUri()).not.toBeUndefined()
 
       # destroy all items
-      expect(workspace.getActivePaneItem().getUri()).toBe 'a'
+      expect(workspace.getActivePaneItem().getUri()).toBe 'file1'
       pane.destroyActiveItem()
       expect(workspace.getActivePaneItem().getUri()).toBe 'b'
       pane.destroyActiveItem()
-      expect(workspace.getActivePaneItem().getUri()).toBe 'file1'
+      expect(workspace.getActivePaneItem().getUri()).toBe 'a'
       pane.destroyActiveItem()
 
       # reopens items with uris
       expect(workspace.getActivePaneItem()).toBeUndefined()
       workspace.reopenItemSync()
-      expect(workspace.getActivePaneItem().getUri()).toBe 'file1'
+      expect(workspace.getActivePaneItem().getUri()).toBe 'a'
 
       # does not reopen items that are already open
       workspace.openSync('b')
       expect(workspace.getActivePaneItem().getUri()).toBe 'b'
       workspace.reopenItemSync()
-      expect(workspace.getActivePaneItem().getUri()).toBe 'a'
+      expect(workspace.getActivePaneItem().getUri()).toBe 'file1'
 
   describe "core:close", ->
     it "closes the active pane item until all that remains is a single empty pane", ->