Add option not to read body in Response.parse.

This allows keeping the connection open after reading the response
to a CONNECT request.

src/websockets/http11.py

@@ -210,6 +210,7 @@ def parse(
         read_line: Callable[[int], Generator[None, None, bytes]],
         read_exact: Callable[[int], Generator[None, None, bytes]],
         read_to_eof: Callable[[int], Generator[None, None, bytes]],
+        include_body: bool = True,
     ) -> Generator[None, None, Response]:
         """
         Parse a WebSocket handshake response.
@@ -265,9 +266,12 @@ def parse(
 
         headers = yield from parse_headers(read_line)
 
-        body = yield from read_body(
-            status_code, headers, read_line, read_exact, read_to_eof
-        )
+        if include_body:
+            body = yield from read_body(
+                status_code, headers, read_line, read_exact, read_to_eof
+            )
+        else:
+            body = b""
 
         return cls(status_code, reason, headers, body)
 

tests/test_http11.py

@@ -130,11 +130,12 @@ def setUp(self):
         super().setUp()
         self.reader = StreamReader()
 
-    def parse(self):
+    def parse(self, **kwargs):
         return Response.parse(
             self.reader.read_line,
             self.reader.read_exact,
             self.reader.read_to_eof,
+            **kwargs,
         )
 
     def test_parse(self):
@@ -322,6 +323,11 @@ def test_parse_body_not_modified(self):
         response = self.assertGeneratorReturns(self.parse())
         self.assertEqual(response.body, b"")
 
+    def test_parse_without_body(self):
+        self.reader.feed_data(b"HTTP/1.1 200 Connection Established\r\n\r\n")
+        response = self.assertGeneratorReturns(self.parse(include_body=False))
+        self.assertEqual(response.body, b"")
+
     def test_serialize(self):
         # Example from the protocol overview in RFC 6455
         response = Response(