Allow providing credentials to HTTPS_PROXY

tests/http/test_proxyagent.py

@@ -12,6 +12,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import base64
 import logging
 import os
 from unittest.mock import patch
@@ -240,7 +241,10 @@ def test_http_request_via_proxy(self):
         body = self.successResultOf(treq.content(resp))
         self.assertEqual(body, b"result")
 
-    @patch.dict(os.environ, {"https_proxy": "proxy.com", "no_proxy": "unused.com"})
+    @patch.dict(
+        os.environ,
+        {"https_proxy": "bob:pinkponies@proxy.com", "no_proxy": "unused.com"},
+    )
     def test_https_request_via_proxy(self):
         agent = ProxyAgent(
             self.reactor,
@@ -278,6 +282,16 @@ def test_https_request_via_proxy(self):
         self.assertEqual(request.method, b"CONNECT")
         self.assertEqual(request.path, b"test.com:443")
 
+        # Check that credentials have been supplied for the proxy
+        proxy_auth_header_values = request.requestHeaders.getRawHeaders(
+            b"Proxy-Authorization"
+        )
+
+        # Compute the correct header value for Proxy-Authorization
+        encoded_credentials = base64.b64encode(b"bob:pinkponies")
+        expected_header_value = b"Basic " + encoded_credentials
+        self.assertIn(expected_header_value, proxy_auth_header_values)
+
         # tell the proxy server not to close the connection
         proxy_server.persistent = True
 
@@ -312,6 +326,13 @@ def test_https_request_via_proxy(self):
         self.assertEqual(request.method, b"GET")
         self.assertEqual(request.path, b"/abc")
         self.assertEqual(request.requestHeaders.getRawHeaders(b"host"), [b"test.com"])
+
+        # Check that the destination server DID NOT receive proxy credentials
+        proxy_auth_header_values = request.requestHeaders.getRawHeaders(
+            b"Proxy-Authorization"
+        )
+        self.assertIsNone(proxy_auth_header_values)
+
         request.write(b"result")
         request.finish()