GH-125: Support multiple headers with same key

Fixes: GH-125

httpbin/core.py

@@ -16,7 +16,7 @@ import random
 import base64
 
 from flask import Flask, Response, request, render_template, redirect, jsonify, make_response
-from werkzeug.datastructures import WWWAuthenticate
+from werkzeug.datastructures import WWWAuthenticate, MultiDict
 from werkzeug.http import http_date
 from werkzeug.wrappers import BaseResponse
 from six.moves import range as xrange
@@ -267,14 +267,20 @@ def view_status_code(codes):
 @app.route('/response-headers')
 def response_headers():
     """Returns a set of response headers from the query string """
-    headers = CaseInsensitiveDict(request.args.items())
-    response = jsonify(headers.items())
+    headers = MultiDict(request.args.items(multi=True))
+    response = jsonify(headers.lists())
 
     while True:
         content_len_shown = response.headers['Content-Length']
-        response = jsonify(response.headers.items())
-        for key, value in headers.items():
-            response.headers[key] = value
+        d = {}
+        for key in response.headers.keys():
+            value = response.headers.get_all(key)
+            if len(value) == 1:
+                value = value[0]
+            d[key] = value
+        response = jsonify(d)
+        for key, value in headers.items(multi=True):
+            response.headers.add(key, value)
         if response.headers['Content-Length'] == content_len_shown:
             break
     return response

test_httpbin.py

@@ -24,6 +24,18 @@ class HttpbinTestCase(unittest.TestCase):
         httpbin.app.debug = True
         self.app = httpbin.app.test_client()
 
+    def test_response_headers_simple(self):
+        response = self.app.get('/response-headers?animal=dog')
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.headers.get_all('animal'), ['dog'])
+        assert json.loads(response.data.decode('utf-8'))['animal'] == 'dog'
+
+    def test_response_headers_multi(self):
+        response = self.app.get('/response-headers?animal=dog&animal=cat')
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.headers.get_all('animal'), ['dog', 'cat'])
+        assert json.loads(response.data.decode('utf-8'))['animal'] == ['dog', 'cat']
+
     def test_base64(self):
         greeting = u'Здравствуй, мир!'
         b64_encoded = _string_to_base64(greeting)