fix(models): honor model_name on /models/load and /models/unload (fixes #977)

backend/tests/test_models_load_by_name.py

@@ -0,0 +1,134 @@
+"""
+Regression tests for POST /models/load and POST /models/unload targeting a
+model by name (issue #977).
+
+``/models/load`` only accepted a ``model_size`` query parameter and always
+dispatched to the default Qwen TTS backend. A caller following the documented
+form — ``POST /models/load {"model_name": "kokoro"}`` — got a 200 back while
+the server silently started a 3.6 GB Qwen 1.7B download instead. ``/models/unload``
+had the same shape: the documented ``{"model_name": ...}`` body was ignored and
+the default Qwen model was unloaded regardless.
+
+Usage:
+    python -m pytest backend/tests/test_models_load_by_name.py -v
+"""
+
+import sys
+from pathlib import Path
+
+import pytest
+from fastapi import FastAPI
+from starlette.testclient import TestClient
+
+# Repo root on sys.path so ``backend`` imports as a package (the routes use
+# package-relative imports).
+sys.path.insert(0, str(Path(__file__).parent.parent.parent))
+
+from backend import backends
+from backend.routes.models import router as models_router
+from backend.services import tts
+
+
+@pytest.fixture
+def loaded(monkeypatch):
+    """Record what the route asked the registry to load/unload."""
+    calls: dict[str, list] = {"by_config": [], "qwen_size": [], "qwen_unload": 0}
+
+    def fake_load_func(config):
+        async def _load():
+            calls["by_config"].append(config.model_name)
+
+        return _load
+
+    def fake_unload_by_config(config):
+        calls["by_config"].append(f"unload:{config.model_name}")
+        return True
+
+    class FakeQwenBackend:
+        async def load_model_async(self, model_size):
+            calls["qwen_size"].append(model_size)
+
+    def fake_unload_tts_model():
+        calls["qwen_unload"] += 1
+
+    monkeypatch.setattr(backends, "get_model_load_func", fake_load_func)
+    monkeypatch.setattr(backends, "unload_model_by_config", fake_unload_by_config)
+    monkeypatch.setattr(tts, "get_tts_model", lambda: FakeQwenBackend())
+    monkeypatch.setattr(tts, "unload_tts_model", fake_unload_tts_model)
+    return calls
+
+
+@pytest.fixture
+def client():
+    app = FastAPI()
+    app.include_router(models_router)
+    with TestClient(app) as test_client:
+        yield test_client
+
+
+def test_load_by_model_name_targets_that_model(client, loaded):
+    """The whole point of #977 — asking for kokoro must not load Qwen."""
+    response = client.post("/models/load", json={"model_name": "kokoro"})
+
+    assert response.status_code == 200
+    assert loaded["by_config"] == ["kokoro"]
+    assert loaded["qwen_size"] == [], "must not touch the default Qwen backend"
+    assert "kokoro" in response.json()["message"]
+
+
+@pytest.mark.parametrize(
+    "model_name",
+    ["qwen-tts-0.6B", "chatterbox-tts", "whisper-turbo", "qwen3-0.6b"],
+)
+def test_load_dispatches_across_engine_families(client, loaded, model_name):
+    """TTS, STT, and LLM entries all resolve through the same registry."""
+    assert client.post("/models/load", json={"model_name": model_name}).status_code == 200
+    assert loaded["by_config"] == [model_name]
+
+
+def test_load_unknown_model_is_rejected(client, loaded):
+    """An unknown name is a 400 that names the valid ids, not a silent Qwen load."""
+    response = client.post("/models/load", json={"model_name": "not-a-model"})
+
+    assert response.status_code == 400
+    assert "kokoro" in response.json()["detail"]
+    assert loaded["by_config"] == []
+    assert loaded["qwen_size"] == []
+
+
+def test_load_without_body_keeps_the_qwen_default(client, loaded):
+    """Pre-existing callers post no body at all."""
+    assert client.post("/models/load").status_code == 200
+    assert loaded["qwen_size"] == ["1.7B"]
+
+
+def test_load_still_honors_the_model_size_query_param(client, loaded):
+    """The legacy ?model_size= form must keep selecting the Qwen variant."""
+    assert client.post("/models/load?model_size=0.6B").status_code == 200
+    assert loaded["qwen_size"] == ["0.6B"]
+
+
+def test_load_model_size_in_body_also_works(client, loaded):
+    assert client.post("/models/load", json={"model_size": "0.6B"}).status_code == 200
+    assert loaded["qwen_size"] == ["0.6B"]
+
+
+def test_unload_by_model_name_targets_that_model(client, loaded):
+    response = client.post("/models/unload", json={"model_name": "chatterbox-tts"})
+
+    assert response.status_code == 200
+    assert loaded["by_config"] == ["unload:chatterbox-tts"]
+    assert loaded["qwen_unload"] == 0, "must not unload the default Qwen model instead"
+
+
+def test_unload_without_body_keeps_the_qwen_default(client, loaded):
+    assert client.post("/models/unload").status_code == 200
+    assert loaded["qwen_unload"] == 1
+    assert loaded["by_config"] == []
+
+
+def test_unload_unknown_model_is_rejected(client, loaded):
+    response = client.post("/models/unload", json={"model_name": "not-a-model"})
+
+    assert response.status_code == 400
+    assert loaded["qwen_unload"] == 0