diff --git a/tools/server/tests/unit/test_router.py b/tools/server/tests/unit/test_router.py
new file mode 100644
index 0000000000..3b1a811c3e
--- /dev/null
+++ b/tools/server/tests/unit/test_router.py
@@ -0,0 +1,50 @@
+import pytest
+from utils import *
+
+server: ServerProcess
+
+@pytest.fixture(autouse=True)
+def create_server():
+    global server
+    server = ServerPreset.router()
+
+
+@pytest.mark.parametrize(
+    "model,success",
+    [
+        ("ggml-org/tinygemma3-GGUF:Q8_0", True),
+        ("non-existent/model", False),
+    ]
+)
+def test_chat_completion_stream(model: str, success: bool):
+    # TODO: make sure the model is in cache (ie. ServerProcess.load_all()) before starting the router server
+    global server
+    server.start()
+    content = ""
+    ex: ServerError | None = None
+    try:
+        res = server.make_stream_request("POST", "/chat/completions", data={
+            "model": model,
+            "max_tokens": 16,
+            "messages": [
+                {"role": "user", "content": "hello"},
+            ],
+            "stream": True,
+        })
+        for data in res:
+            if data["choices"]:
+                choice = data["choices"][0]
+                if choice["finish_reason"] in ["stop", "length"]:
+                    assert "content" not in choice["delta"]
+                else:
+                    assert choice["finish_reason"] is None
+                    content += choice["delta"]["content"] or ''
+    except ServerError as e:
+        ex = e
+
+    if success:
+        assert ex is None
+        assert len(content) > 0
+    else:
+        assert ex is not None
+        assert content == ""
diff --git a/tools/server/tests/utils.py b/tools/server/tests/utils.py
index da703c4c51..a9eec74822 100644
--- a/tools/server/tests/utils.py
+++ b/tools/server/tests/utils.py
@@ -46,7 +46,7 @@ class ServerProcess:
     debug: bool = False
     server_port: int = 8080
     server_host: str = "127.0.0.1"
-    model_hf_repo: str = "ggml-org/models"
+    model_hf_repo: str | None = "ggml-org/models"
     model_hf_file: str | None = "tinyllamas/stories260K.gguf"
     model_alias: str = "tinyllama-2"
     temperature: float = 0.8
@@ -519,9 +519,8 @@ class ServerPreset:
         server = ServerProcess()
         server.offline = True # will be downloaded by load_all()
         # mmproj is already provided by HF registry API
-        server.model_hf_repo = "ggml-org/tinygemma3-GGUF"
-        server.model_hf_file = "tinygemma3-Q8_0.gguf"
-        server.mmproj_url = "https://huggingface.co/ggml-org/tinygemma3-GGUF/resolve/main/mmproj-tinygemma3.gguf"
+        server.model_hf_file = None
+        server.model_hf_repo = "ggml-org/tinygemma3-GGUF:Q8_0"
         server.model_alias = "tinygemma3"
         server.n_ctx = 1024
         server.n_batch = 32
@@ -529,6 +528,21 @@ class ServerPreset:
         server.n_predict = 4
         server.seed = 42
         return server
+    
+    @staticmethod
+    def router() -> ServerProcess:
+        server = ServerProcess()
+        # router server has no models
+        server.model_file = None
+        server.model_alias = None
+        server.model_hf_repo = None
+        server.model_hf_file = None
+        server.n_ctx = 1024
+        server.n_batch = 16
+        server.n_slots = 1
+        server.n_predict = 16
+        server.seed = 42
+        return server
 
 
 def parallel_function_calls(function_list: List[Tuple[Callable[..., Any], Tuple[Any, ...]]]) -> List[Any]: