Update the test federation client to handle streaming responses (#8130)

Now that the server supports streaming back JSON responses, it would be nice to
show the response as it is streamed, in the test tool.

changelog.d/8130.misc

@@ -0,0 +1 @@
+Update the test federation client to handle streaming responses.

scripts-dev/federation_client.py

@@ -21,10 +21,12 @@ import argparse
 import base64
 import json
 import sys
+from typing import Any, Optional
 from urllib import parse as urlparse
 
 import nacl.signing
 import requests
+import signedjson.types
 import srvlookup
 import yaml
 from requests.adapters import HTTPAdapter
@@ -69,7 +71,9 @@ def encode_canonical_json(value):
     ).encode("UTF-8")
 
 
-def sign_json(json_object, signing_key, signing_name):
+def sign_json(
+    json_object: Any, signing_key: signedjson.types.SigningKey, signing_name: str
+) -> Any:
     signatures = json_object.pop("signatures", {})
     unsigned = json_object.pop("unsigned", None)
 
@@ -122,7 +126,14 @@ def read_signing_keys(stream):
     return keys
 
 
-def request_json(method, origin_name, origin_key, destination, path, content):
+def request(
+    method: Optional[str],
+    origin_name: str,
+    origin_key: signedjson.types.SigningKey,
+    destination: str,
+    path: str,
+    content: Optional[str],
+) -> requests.Response:
     if method is None:
         if content is None:
             method = "GET"
@@ -159,11 +170,14 @@ def request_json(method, origin_name, origin_key, destination, path, content):
     if method == "POST":
         headers["Content-Type"] = "application/json"
 
-    result = s.request(
+    return s.request(
-        method=method, url=dest, headers=headers, verify=False, data=content
+        method=method,
+        url=dest,
+        headers=headers,
+        verify=False,
+        data=content,
+        stream=True,
     )
-    sys.stderr.write("Status Code: %d\n" % (result.status_code,))
-    return result.json()
 
 
 def main():
@@ -222,7 +236,7 @@ def main():
     with open(args.signing_key_path) as f:
         key = read_signing_keys(f)[0]
 
-    result = request_json(
+    result = request(
         args.method,
         args.server_name,
         key,
@@ -231,7 +245,12 @@ def main():
         content=args.body,
     )
 
-    json.dump(result, sys.stdout)
+    sys.stderr.write("Status Code: %d\n" % (result.status_code,))
+
+    for chunk in result.iter_content():
+        # we write raw utf8 to stdout.
+        sys.stdout.buffer.write(chunk)
+
     print("")