test(transcriber): cover persisted Whisper model selection

backend/tests/test_transcriber_provider_model_selection.py

@@ -0,0 +1,76 @@
+"""Model-selection contract tests without loading the Whisper runtime."""
+import importlib.util
+import pathlib
+import sys
+import types
+
+
+ROOT = pathlib.Path(__file__).resolve().parents[1]
+MODULE_PATH = ROOT / "app" / "transcriber" / "transcriber_provider.py"
+
+
+class _Logger:
+    def info(self, *_args, **_kwargs):
+        pass
+
+    def warning(self, *_args, **_kwargs):
+        pass
+
+    def error(self, *_args, **_kwargs):
+        pass
+
+
+class _Whisper:
+    def __init__(self, model_size, device):
+        self.model_size = model_size
+        self.device = device
+
+
+def _stub(monkeypatch, name, **attrs):
+    module = types.ModuleType(name)
+    for key, value in attrs.items():
+        setattr(module, key, value)
+    monkeypatch.setitem(sys.modules, name, module)
+
+
+def _load_provider(monkeypatch):
+    _stub(monkeypatch, "app")
+    _stub(monkeypatch, "app.transcriber")
+    _stub(monkeypatch, "app.utils")
+    _stub(monkeypatch, "app.transcriber.groq", GroqTranscriber=object)
+    _stub(monkeypatch, "app.transcriber.whisper", WhisperTranscriber=_Whisper)
+    _stub(monkeypatch, "app.transcriber.bcut", BcutTranscriber=object)
+    _stub(monkeypatch, "app.transcriber.kuaishou", KuaishouTranscriber=object)
+    _stub(monkeypatch, "app.utils.logger", get_logger=lambda _name: _Logger())
+
+    spec = importlib.util.spec_from_file_location("transcriber_provider_under_test", MODULE_PATH)
+    module = importlib.util.module_from_spec(spec)
+    assert spec.loader is not None
+    spec.loader.exec_module(module)
+    return module
+
+
+def test_explicit_whisper_model_overrides_docker_default(monkeypatch):
+    """A saved UI choice must not be replaced by WHISPER_MODEL_SIZE."""
+    provider = _load_provider(monkeypatch)
+    monkeypatch.setenv("WHISPER_MODEL_SIZE", "tiny")
+
+    transcriber = provider.get_transcriber(
+        transcriber_type="fast-whisper",
+        model_size="large-v3-turbo",
+        device="cpu",
+    )
+
+    assert transcriber.model_size == "large-v3-turbo"
+
+
+def test_switching_whisper_models_rebuilds_the_cached_instance(monkeypatch):
+    """Caching only by transcriber type would keep returning the first model."""
+    provider = _load_provider(monkeypatch)
+    monkeypatch.delenv("WHISPER_MODEL_SIZE", raising=False)
+
+    base = provider.get_transcriber("fast-whisper", model_size="base", device="cpu")
+    turbo = provider.get_transcriber("fast-whisper", model_size="large-v3-turbo", device="cpu")
+
+    assert turbo is not base
+    assert turbo.model_size == "large-v3-turbo"