config: improve management of CORS origins

- Replaces the onliner converting the value of the env variable into a
  list by a function. This allows to test this conversion.

Co-Authored-by: iGor milhit <igor@milhit.ch>

config.py

@@ -1,5 +1,6 @@
 from functools import lru_cache
 
+from pydantic import Field, computed_field
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
@@ -9,13 +10,29 @@ class Settings(BaseSettings):
         env_file_encoding = "utf-8"
     )
 
-    # CORS
-    cors_origins: str = "http://localhost:5173"
+    # CORS as a private field with a string type:
+    cors_origins_raw: str = Field(
+        default="http://localhost:5173",
+        alias="cors_origins"
+    )
+
+    @computed_field
+    @property
+    def cors_origins(self) -> list[str]:
+        """Converts a string into list."""
+        if isinstance(self.cors_origins_raw, list):
+            return self.cors_origins_raw
+        return [
+            origin.strip()
+            for origin in self.cors_origins_raw.split(",")
+            if origin.strip()
+        ]
 
     # Autres configurations futures
     app_name: str = "Dough Calculator"
     debug: bool = False
 
+
 @lru_cache
 def get_settings() -> Settings:
     return Settings()

main.py

@@ -8,11 +8,9 @@ from config import get_settings
 app = FastAPI()
 settings = get_settings()
 
-origins =  [origin.strip() for origin in settings.cors_origins.split(",")]
-
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=origins,
+    allow_origins=settings.cors_origins,
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],

tests/test_config.py

@@ -1,56 +1,56 @@
-from config import Settings, get_settings
+from config import Settings
 
 
-def test_settings_default_values():
-    """Vérifie les valeurs par défaut"""
-    settings = Settings()
-    assert settings.cors_origins == "http://localhost:5173"
-    assert settings.app_name == "Dough Calculator"
-    assert settings.debug is False
+class TestSettings:
+    """Tests the Settings model."""
 
-def test_settings_from_env(monkeypatch):
-    """Vérifie le chargement depuis variables d'environnement"""
-    monkeypatch.setenv("CORS_ORIGINS", "https://example.com,https://test.com")
-    monkeypatch.setenv("APP_NAME", "Test App")
-    monkeypatch.setenv("DEBUG", "true")
+    def test_default_cors_origins(self):
+        """Test the default value."""
+        settings = Settings()
+        assert settings.cors_origins == ["http://localhost:5173"]
+        assert isinstance(settings.cors_origins, list)
 
-    # Vider le cache pour forcer le rechargement
-    get_settings.cache_clear()
+    def test_cors_origins_single_value(self, monkeypatch):
+        """Test with only one origin in the env variable."""
+        monkeypatch.setenv("CORS_ORIGINS", "http://example.com")
+        settings = Settings()
+        assert settings.cors_origins == ["http://example.com"]
 
-    settings = get_settings()
-    assert settings.cors_origins == "https://example.com,https://test.com"
-    assert settings.app_name == "Test App"
-    assert settings.debug is True
+    def test_cors_origins_multiple_values(self, monkeypatch):
+        """Test with several origins comma separated."""
+        monkeypatch.setenv(
+            "CORS_ORIGINS", "http://a.com,http://b.com,http://c.com"
+        )
+        settings = Settings()
+        assert settings.cors_origins == [
+            "http://a.com", "http://b.com", "http://c.com"
+        ]
 
-def test_cors_origins_parsing():
-    """Vérifie que les origines CORS sont correctement parsées"""
-    settings = Settings(cors_origins="http://localhost:3000,https://prod.com")
-    origins = [origin.strip() for origin in settings.cors_origins.split(",")]
+    def test_cors_origins_with_spaces(self, monkeypatch):
+        """Test with origins with spaces around commas."""
+        monkeypatch.setenv(
+            "CORS_ORIGINS", "http://a.com , http://b.com , http://c.com"
+        )
+        settings = Settings()
+        assert settings.cors_origins == [
+            "http://a.com", "http://b.com", "http://c.com"
+        ]
 
-    assert len(origins) == 2
-    assert "http://localhost:3000" in origins
-    assert "https://prod.com" in origins
+    def test_cors_origins_empty_string(self, monkeypatch):
+        """Test with an empty list."""
+        monkeypatch.setenv("CORS_ORIGINS", "")
+        settings = Settings()
+        assert settings.cors_origins == []
 
-def test_settings_cache():
-    """Vérifie que le cache fonctionne"""
-    get_settings.cache_clear()
+    def test_cors_origins_with_trailing_comma(self, monkeypatch):
+        """Test with a trailing comma."""
+        monkeypatch.setenv("CORS_ORIGINS", "http://a.com,http://b.com,")
+        settings = Settings()
+        assert settings.cors_origins == ["http://a.com", "http://b.com"]
 
-    settings1 = get_settings()
-    settings2 = get_settings()
+    def test_cors_origins_type_is_list(self):
+        """Test that the returned type is a list"""
+        settings = Settings()
+        assert isinstance(settings.cors_origins, list)
+        assert all(isinstance(origin, str) for origin in settings.cors_origins)
 
-    # Même instance en mémoire grâce au cache
-    assert settings1 is settings2
-
-def test_env_file_loading(tmp_path, monkeypatch):
-    """Vérifie le chargement depuis fichier .env"""
-    # Créer un fichier .env temporaire
-    env_file = tmp_path / ".env"
-    env_file.write_text("CORS_ORIGINS=https://from-file.com\nDEBUG=true")
-
-    # Changer le répertoire de travail
-    monkeypatch.chdir(tmp_path)
-    get_settings.cache_clear()
-
-    settings = Settings()
-    assert settings.cors_origins == "https://from-file.com"
-    assert settings.debug is True