Replacing the 'Content-Type' header overwrite with a generic header o…

README.md

@@ -221,15 +221,17 @@ module.exports = function(options) {
 };
 ```
 
-If the transform needs to change the `Content-Type` of the response, a `contentType` property can be declared on the transform function that the proxy will recognize and set the header accordingly.
+If the transform needs to change the headers of the response, a `headers` object can be declared on the transform function that the proxy will recognize and overwrite each header accordingly.
+
+If you wish to only overwrite headers, you can omit the transform function.
 
 ```js
 module.exports = function() {
   return {
-    name: 'appender',
-    contentType: 'application/json',
-    transform: function() {
-      return through2(...)
+    name: 'header-overwrite',
+    headers: {
+      'content-type': 'application/json',
+      'location': 'http://localhost'
     }
   };
 }

lib/proxy.js

@@ -281,11 +281,14 @@ module.exports = function(options) {
     // Pipe the stream through each transform in sequence
     transforms.forEach(function(transform) {
       debug('applying transform %s', transform.name);
-      if (transform.contentType) {
-        headers['Content-Type'] = transform.contentType;
+      if (transform.headers) {
+        for (var key in transform.headers) {
+          headers[key] = transform.headers[key];
+        }
+      }
+      if (transform.transform) {
+        stream = stream.pipe(transform.transform());
       }
-
-      stream = stream.pipe(transform.transform());
     });
 
     return stream;

test/transforms.js

@@ -35,6 +35,17 @@ describe('response transforms', function() {
       .end(done);
   });
 
+  it('transforms headers', function(done) {
+    this.proxyOptions.transforms = [
+      headerTransform('text/html', 'http://localhost')
+    ];
+    supertest(this.server).get('/proxy')
+      .expect(200)
+      .expect('Content-Type', /^text\/html/)
+      .expect('location', 'http://localhost')
+      .end(done);
+  });
+
   it('recreates the transform stream between requests', function(done) {
     var self = this;
     supertest(self.server).get('/proxy')
@@ -101,13 +112,25 @@ describe('response transforms', function() {
   function appenderTransform(appendText, contentType) {
     return {
       name: 'appender',
-      contentType: contentType,
-      transform: function() {
-        return through2(function(chunk, enc, cb) {
+      headers: {
+        'Content-Type': contentType
+      },
+      transform: function () {
+        return through2(function (chunk, enc, cb) {
           this.push(chunk + appendText);
           cb();
         });
       }
     };
   }
+
+  function headerTransform(contentType, location) {
+    return {
+      name: 'overwrite-headers',
+      headers: {
+        'Content-Type': contentType,
+        'location': location
+      }
+    }
+  }
 });