support async function for readFileFn

package.json

@@ -39,7 +39,7 @@
     "jasmine-core": "^2.4.1",
     "karma": "0.13",
     "karma-chrome-launcher": "^1.0.1",
-    "karma-coverage": "0.5.5",
+    "karma-coverage": "^2.0.3",
     "karma-firefox-launcher": "0.1.7",
     "karma-jasmine": "0.3",
     "karma-sauce-launcher": "0.3.1",

src/flow.js

@@ -1329,31 +1329,31 @@
      * Finish preprocess state
      * @function
      */
-    preprocessFinished: function () {
+    preprocessFinished: async function () {
       // Re-compute the endByte after the preprocess function to allow an
       // implementer of preprocess to set the fileObj size
       this.endByte = this.computeEndByte();
 
       this.preprocessState = 2;
-      this.send();
+      await this.send();
     },
 
     /**
      * Finish read state
      * @function
      */
-    readFinished: function (bytes) {
+    readFinished: async function (bytes) {
       this.readState = 2;
       this.bytes = bytes;
-      this.send();
+      await this.send();
     },
 
 
     /**
      * Uploads the actual data in a POST call
      * @function
      */
-    send: function () {
+    send: async function () {
       var preprocess = this.flowObj.opts.preprocess;
       var read = this.flowObj.opts.readFileFn;
       if (typeof preprocess === 'function') {
@@ -1369,7 +1369,11 @@
       switch (this.readState) {
         case 0:
           this.readState = 1;
-          read(this.fileObj, this.startByte, this.endByte, this.fileObj.file.type, this);
+          if (read.constructor.name == 'AsyncFunction') {
+              await read(this.fileObj, this.startByte, this.endByte, this.fileObj.file.type, this);
+          } else {
+              read(this.fileObj, this.startByte, this.endByte, this.fileObj.file.type, this);
+          }
           return;
         case 1:
           return;