detect JSON by provided content-type instead of content check

Author: Artemy Tregubenko

src/http.js

@@ -67,8 +67,8 @@ export default function http(url, request = {}) {
 // exported for testing
 export const shouldDownloadAsText = (contentType = '') => /json|xml|yaml|text/.test(contentType)
 
-function parseBody(body) {
-  if (/^\s*\{/.test(body)) {
+function parseBody(body, contentType) {
+  if (contentType === 'application/json') {
     return JSON.parse(body)
   }
   return jsYaml.safeLoad(body)
@@ -84,7 +84,8 @@ export function serializeRes(oriRes, url, {loadSpec = false} = {}) {
     headers: serializeHeaders(oriRes.headers)
   }
 
-  const useText = loadSpec || shouldDownloadAsText(res.headers['content-type'])
+  const contentType = res.headers['content-type']
+  const useText = loadSpec || shouldDownloadAsText(contentType)
 
   // Note: Response.blob not implemented in node-fetch 1.  Use buffer instead.
   const getBody = useText ? oriRes.text : (oriRes.blob || oriRes.buffer)
@@ -95,7 +96,7 @@ export function serializeRes(oriRes, url, {loadSpec = false} = {}) {
 
     if (useText) {
       try {
-        const obj = parseBody(body)
+        const obj = parseBody(body, contentType)
         res.body = obj
         res.obj = obj
       }