improvement: add newline remover for Header values (via #1468)

Author: shockey

src/http.js

@@ -24,6 +24,22 @@ export default async function http(url, request = {}) {
   // the search string, but much easier to manipulate the req.query object
   self.mergeInQueryOrForm(request)
 
+  // Newlines in header values cause weird error messages from `window.fetch`,
+  // so let's massage them out.
+  // Context: https://stackoverflow.com/a/50709178
+  if (request.headers) {
+    Object.keys(request.headers).forEach((headerName) => {
+      const value = request.headers[headerName]
+
+      if (typeof value === 'string') {
+        request.headers[headerName] = value.replace(/\n+/g, ' ')
+      }
+    })
+  }
+
+  // Wait for the request interceptor, if it was provided
+  // WARNING: don't put anything between this and the request firing unless
+  // you have a good reason!
   if (request.requestInterceptor) {
     request = await request.requestInterceptor(request) || request
   }

test/http.js

@@ -331,6 +331,29 @@ describe('http', () => {
         expect(response.status).toEqual(200)
       }).then(fetchMock.restore)
     })
+
+    test('should remove newlines from header values', () => {
+      // Given
+      fetchMock.get('*', (url, opts) => {
+        return {
+          body: opts.headers.WilliamCWilliamsHeader
+        }
+      })
+      const req = {
+        url: 'http://example.com',
+        method: 'GET',
+        headers: {
+          WilliamCWilliamsHeader: 'so much depends\nupon\n\na red wheel\nbarrow'
+        }
+      }
+
+      return http('http://example.com', req).then((response) => {
+        expect(response.url).toEqual('http://example.com')
+        expect(response.data.toString()).toEqual(
+          'so much depends upon a red wheel barrow'
+        )
+      }).then(fetchMock.restore)
+    })
   })
 
   describe('serializeRes', () => {