Add tests to prevent superfluous update events

Author: winstliu

spec/buffer-search-spec.coffee

@@ -376,6 +376,25 @@ describe "BufferSearch", ->
 
         expect(scannedRanges()).toEqual []
 
+    describe "when no markers are affected in a change event", ->
+      it "does not emit an update event", ->
+        editor.setCursorBufferPosition([0, 0])
+        editor.backspace()
+        advanceClock(editor.buffer.stoppedChangingDelay)
+        expectNoUpdateEvent()
+
+    describe "when the find pattern is invalid and a change occurs", ->
+      it "does not attempt to update markers", ->
+        model.search "a(",
+          caseSensitive: false
+          useRegex: true
+          wholeWord: false
+
+        editor.insertText(".")
+        advanceClock(editor.buffer.stoppedChangingDelay)
+
+        expectNoUpdateEvent()
+
   describe "replacing a search result", ->
     beforeEach ->
       editor.scanInBufferRange.reset()