fix(file_list): Incorrect response after remove and add file

Remove and then immediately add same file can lead to
incorrect content in response. Because pending timeout after remove
may resolve early then file will be processed, and in response get not
processed content.

lib/file_list.js

@@ -111,9 +111,7 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
   };
 
   var resolveDeferred = function(files) {
-    if (pendingTimeout) {
-      clearTimeout(pendingTimeout);
-    }
+    clearPendingTimeout();
 
     if (!errors.length) {
       pendingDeferred.resolve(files || resolveFiles(self.buckets));
@@ -125,9 +123,7 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
   };
 
   var fireEventAndDefer = function() {
-    if (pendingTimeout) {
-      clearTimeout(pendingTimeout);
-    }
+    clearPendingTimeout();
 
     if (!pendingDeferred) {
       pendingDeferred = q.defer();
@@ -137,6 +133,12 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
     pendingTimeout = setTimeout(resolveDeferred, batchInterval);
   };
 
+  var clearPendingTimeout = function() {
+    if (pendingTimeout) {
+      clearTimeout(pendingTimeout);
+    }
+  };
+
 
   // re-glob all the patterns
   this.refresh = function() {
@@ -171,9 +173,7 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
       emitter.emit('file_list_modified', pendingDeferred.promise);
     }
 
-    if (pendingTimeout) {
-      clearTimeout(pendingTimeout);
-    }
+    clearPendingTimeout();
 
     patterns.forEach(function(patternObject, i) {
       var pattern = patternObject.pattern;
@@ -302,6 +302,8 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
     var addedFile = new File(path);
     buckets[i].push(addedFile);
 
+    clearPendingTimeout();
+
     return fs.stat(path, function(err, stat) {
       // in the case someone refresh() the list before stat callback
       if (self.buckets === buckets) {

test/unit/file_list.spec.coffee

@@ -589,7 +589,6 @@ describe 'file_list', ->
   # Batch Interval processing
   #============================================================================
   describe 'batch interval', ->
-
     it 'should batch multiple changes within an interval', (done) ->
       timeoutSpy = sinon.stub().returns true
       globals_ = setTimeout: timeoutSpy
@@ -631,6 +630,36 @@ describe 'file_list', ->
           expect(timeoutSpy).to.have.been.called
           timeoutSpy.lastCall.args[0]()
 
+    it 'should wait while file preprocessing, if file was deleted and immediately added', (done) ->
+      clock = sinon.useFakeTimers()
+
+      m = mocks.loadFile __dirname + '/../../lib/file_list.js', mocks_, global
+      list = new m.List patterns('/a.*'), [], emitter, preprocessMock, 1000
+
+      refreshListAndThen (files) ->
+        preprocessMock.reset()
+
+        emitter.once 'file_list_modified', (promise) ->
+          expect(promise).to.be.fulfilled.then((files)->
+
+            # expect file will be preprocessed when file list promise
+            # resolved, else we will get incorrect(not processed) content in response
+            expect(preprocessMock.callCount).to.equal 1
+          ).should.notify(done)
+
+        # Remove and then immediately add file to the bucket
+        list.removeFile '/a.txt'
+        list.addFile '/a.txt'
+
+        # Timed remove pending timeout
+        # but processing file after add is not completed
+        clock.tick(1000)
+
+        # Finish processing file
+        process.nextTick -> process.nextTick ->
+          clock.tick(1000)
+
+      clock.tick()
 
   #============================================================================
   # Win Globbing