[CI/Build] Use a fixed seed to avoid flaky tests (#14480)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/entrypoints/openai/test_chat_echo.py

@@ -24,8 +24,6 @@ def server():
         "4080",
         "--chat-template",
         DUMMY_CHAT_TEMPLATE,
-        "--seed",
-        "0",
     ]
 
     with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:

tests/entrypoints/openai/test_metrics.py

@@ -47,8 +47,6 @@ def default_server_args():
         "--enforce-eager",
         "--max-num-seqs",
         "128",
-        "--seed",
-        "0",
     ]
 
 

tests/entrypoints/openai/test_root_path.py

@@ -30,8 +30,6 @@ def server():
         "/" + ROOT_PATH,
         "--chat-template",
         DUMMY_CHAT_TEMPLATE,
-        "--seed",
-        "0",
     ]
     envs = os.environ.copy()
 

tests/utils.py

@@ -76,6 +76,7 @@ class RemoteOpenAIServer:
                  vllm_serve_args: list[str],
                  *,
                  env_dict: Optional[dict[str, str]] = None,
+                 seed: Optional[int] = 0,
                  auto_port: bool = True,
                  max_wait_seconds: Optional[float] = None) -> None:
         if auto_port:
@@ -87,6 +88,12 @@ class RemoteOpenAIServer:
             vllm_serve_args = vllm_serve_args + [
                 "--port", str(get_open_port())
             ]
+        if seed is not None:
+            if "--seed" in vllm_serve_args:
+                raise ValueError("You have manually specified the seed "
+                                 f"when `seed={seed}`.")
+
+            vllm_serve_args = vllm_serve_args + ["--seed", str(seed)]
 
         parser = FlexibleArgumentParser(
             description="vLLM's remote OpenAI server.")