fix: allow multiple body parser coexist

lib/form.js

@@ -37,10 +37,7 @@ module.exports = function(req, opts){
   opts.qs = opts.qs || qs;
 
   // raw-body returns a Promise when no callback is specified
-  return Promise.resolve()
-    .then(function() {
-      return raw(inflate(req), opts);
-    })
+  return raw(inflate(req), opts)
     .then(function(str){
       try {
         var parsed = opts.qs.parse(str, queryString);

lib/json.js

@@ -36,10 +36,7 @@ module.exports = function(req, opts){
   var strict = opts.strict !== false;
 
   // raw-body returns a promise when no callback is specified
-  return Promise.resolve()
-    .then(function() {
-      return raw(inflate(req), opts);
-    })
+  return raw(inflate(req), opts)
     .then(function(str) {
       try {
         var parsed = parse(str);

lib/text.js

@@ -30,10 +30,7 @@ module.exports = function(req, opts){
   opts.limit = opts.limit || '1mb';
 
   // raw-body returns a Promise when no callback is specified
-  return Promise.resolve()
-    .then(function() {
-      return raw(inflate(req), opts);
-    })
+  return raw(inflate(req), opts)
     .then(str => {
       // ensure return the same format with json / form
       return opts.returnRawBody ? { parsed: str, raw: str } : str;

test/any.js

@@ -228,4 +228,33 @@ describe('parse(req, opts)', function(){
     })
   })
 
+  describe('multiple parser coexist', function(){
+    it('should parse', function(done){
+      var app = koa();
+
+      app.use(function *(next){
+        this.request.textParser = parse.text(this);
+        yield next;
+      });
+      app.use(function *(next){
+        this.request.formParser = parse.form(this);
+        yield next;
+      });
+      app.use(function *(){
+        this.body = {
+          json: yield parse(this),
+          text: yield this.request.textParser,
+          form: yield this.request.formParser
+        };
+      });
+
+      request(app.listen())
+      .post('/')
+      .set('content-type', 'application/json')
+      .send('{"hello":"world"}')
+      .expect(200)
+      .expect({"json":{"hello":"world"},"text":"{\"hello\":\"world\"}","form":{"{\"hello\":\"world\"}":""}}, done);
+    })
+  })
+
 })