Pull test_utils server-launch boilerplate into reusable helpers (#26804)

python/sglang/test/test_utils.py

@@ -755,6 +755,43 @@ def _create_clean_subprocess_env(env: dict) -> dict:
     return child_env
 
 
+def _subprocess_popen_with_outputs(
+    command: list,
+    env: Optional[dict],
+    return_stdout_stderr: Optional[tuple],
+) -> subprocess.Popen:
+    if not return_stdout_stderr:
+        return subprocess.Popen(command, stdout=None, stderr=None, env=env)
+
+    process = subprocess.Popen(
+        command,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        env=env,
+        text=True,
+        bufsize=1,
+    )
+
+    def _dump(src, sinks):
+        for line in iter(src.readline, ""):
+            for sink in sinks:
+                sink.write(line)
+                sink.flush()
+        src.close()
+
+    threading.Thread(
+        target=_dump,
+        args=(process.stdout, [return_stdout_stderr[0], sys.stdout]),
+        daemon=True,
+    ).start()
+    threading.Thread(
+        target=_dump,
+        args=(process.stderr, [return_stdout_stderr[1], sys.stderr]),
+        daemon=True,
+    ).start()
+    return process
+
+
 def _launch_server_process(
     command: List[str],
     env: dict,
@@ -777,37 +814,11 @@ def _launch_server_process(
     hf_hub_offline = child_env.get("HF_HUB_OFFLINE", "0")
     print(f"CI_OFFLINE: Launching server HF_HUB_OFFLINE={hf_hub_offline} model={model}")
 
-    if return_stdout_stderr:
+    return _subprocess_popen_with_outputs(
-        proc = subprocess.Popen(
+        command=command,
-            command,
+        env=child_env,
-            stdout=subprocess.PIPE,
+        return_stdout_stderr=return_stdout_stderr,
-            stderr=subprocess.PIPE,
+    )
-            env=child_env,
-            text=True,
-            bufsize=1,
-        )
-
-        def _dump(src, sinks):
-            for line in iter(src.readline, ""):
-                for sink in sinks:
-                    sink.write(line)
-                    sink.flush()
-            src.close()
-
-        threading.Thread(
-            target=_dump,
-            args=(proc.stdout, [return_stdout_stderr[0], sys.stdout]),
-            daemon=True,
-        ).start()
-        threading.Thread(
-            target=_dump,
-            args=(proc.stderr, [return_stdout_stderr[1], sys.stderr]),
-            daemon=True,
-        ).start()
-    else:
-        proc = subprocess.Popen(command, stdout=None, stderr=None, env=child_env)
-
-    return proc
 
 
 def _wait_for_server_health(
@@ -1024,6 +1035,7 @@ def popen_launch_pd_server(
     api_key: Optional[str] = None,
     other_args: list[str] = (),
     env: Optional[dict] = None,
+    return_stdout_stderr: Optional[tuple] = None,
 ):
     _, host, port = base_url.split(":")
     host = host[2:]
@@ -1059,9 +1071,11 @@ def popen_launch_pd_server(
     if env is not None:
         env = {**os.environ, **env}
 
-    process = subprocess.Popen(command, stdout=None, stderr=None, env=env)
+    return _subprocess_popen_with_outputs(
-
+        command=command,
-    return process
+        env=env,
+        return_stdout_stderr=return_stdout_stderr,
+    )
 
 
 def get_similarities(vec1, vec2):