refactor(filelist): rename promise -> lastCompletedRefresh and remove…

… unused promise

lib/file-list.js

@@ -65,7 +65,7 @@ class FileList {
     // So we know we are refreshing when this promise
     // is still pending, and we are done when it's either
     // resolved or rejected.
-    this._refreshing = Promise.resolve()
+    this._refreshing = null
 
     // Emit the `file_list_modified` event.
     // This function is debounced to the value of `autoWatchBatchDelay`
@@ -131,16 +131,16 @@ class FileList {
 
   // Check if we are currently refreshing
   _isRefreshing () {
-    return this._refreshing.isPending()
+    return this._refreshing && this._refreshing.isPending()
   }
 
   // Do the actual work of refreshing
   _refresh () {
     const buckets = this.buckets
     const matchedFiles = new Set()
 
-    let promise
-    promise = Promise.map(this._patterns, (patternObject) => {
+    let lastCompletedRefresh = this._refreshing
+    lastCompletedRefresh = Promise.map(this._patterns, (patternObject) => {
       const pattern = patternObject.pattern
       const type = patternObject.type
 
@@ -195,15 +195,19 @@ class FileList {
         })
     })
       .then(() => {
-        if (this._refreshing !== promise) {
+        // When we return from this function the file processing chain will be
+        // complete. In the case of two fast refresh() calls, the second call
+        // will overwrite this._refreshing, and we want the status to reflect
+        // the second call and skip the modification event from the first call.
+        if (this._refreshing !== lastCompletedRefresh) {
           return this._refreshing
         }
         this.buckets = buckets
         this._emitModified(true)
         return this.files
       })
 
-    return promise
+    return lastCompletedRefresh
   }
 
   // Public Interface