Step 1 complete!

tests/test_config.py

@@ -1,16 +1,34 @@
 """Tests for transcription.config — settings loading, provider defaults, and paths."""
 
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
 from transcription.config import Provider, Settings
 
 
+def _make_settings(**overrides) -> Settings:
+    """Build a Settings instance with a dummy API key unless overridden."""
+    defaults = {"openrouter_api_key": "test-key-abc123"}
+    defaults.update(overrides)
+    return Settings(**defaults)
+
+
 class TestSettingsLoading:
     """Verify Settings construction and required-field validation."""
 
-    def test_loads_from_env(self):
+    def test_loads_from_env(self, monkeypatch):
         """Settings constructs when OPENROUTER_API_KEY is provided."""
+        monkeypatch.setenv("OPENROUTER_API_KEY", "test-key-xyz")
+        settings = Settings()
+        assert settings.openrouter_api_key == "test-key-xyz"
 
-    def test_requires_api_key(self):
+    def test_requires_api_key(self, monkeypatch):
         """Settings raises ValidationError when OPENROUTER_API_KEY is missing."""
+        monkeypatch.delenv("OPENROUTER_API_KEY", raising=False)
+        with pytest.raises(ValidationError):
+            Settings(_env_file=None)
 
 
 class TestProviderSettings:
@@ -18,12 +36,21 @@ class TestProviderSettings:
 
     def test_defaults_to_openrouter(self):
         """Default provider is openrouter when not explicitly set."""
+        settings = _make_settings()
+        assert settings.provider == Provider.OPENROUTER
+        assert settings.provider == "openrouter"
 
     def test_rejects_invalid_value(self):
         """Setting PROVIDER to an invalid value raises ValidationError."""
+        with pytest.raises(ValidationError):
+            _make_settings(provider="not-a-provider")
 
     def test_optional_fields_default_to_none(self):
         """provider_model, openrouter_http_referer, and openrouter_app_title are None when unset."""
+        settings = _make_settings()
+        assert settings.provider_model is None
+        assert settings.openrouter_http_referer is None
+        assert settings.openrouter_app_title is None
 
 
 class TestPathSettings:
@@ -31,3 +58,6 @@ class TestPathSettings:
 
     def test_path_fields_are_path_objects(self):
         """upload_dir and prompt_dir are Path instances."""
+        settings = _make_settings()
+        assert isinstance(settings.upload_dir, Path)
+        assert isinstance(settings.prompt_dir, Path)