test: upgrade backend test suite, implement unit tests, and modernize CRUD patterns

backend/tests/test_config.py

@@ -0,0 +1,37 @@
+import pytest
+from app.config import Settings
+
+def test_settings_defaults():
+    """Test that default settings are correctly loaded."""
+    # We instantiate a new Settings object to test the class directly, 
+    # rather than using the already-initialized 'settings' instance in app.config.
+    s = Settings(_env_file=None)
+    assert s.DATABASE_URL == "sqlite+aiosqlite:///./data/sleep.db"
+    assert s.CORS_ORIGINS == "http://localhost:5173"
+    assert s.LOG_LEVEL == "info"
+
+def test_settings_env_overrides(monkeypatch):
+    """Test that environment variables correctly override defaults."""
+    # Set environment variables using monkeypatch
+    monkeypatch.setenv("DATABASE_URL", "postgresql+asyncpg://testuser:testpass@localhost/testdb")
+    monkeypatch.setenv("CORS_ORIGINS", "http://example.com")
+    monkeypatch.setenv("LOG_LEVEL", "debug")
+
+    # Re-instantiate Settings to pick up the new environment variables
+    s = Settings(_env_file=None)
+
+    assert s.DATABASE_URL == "postgresql+asyncpg://testuser:testpass@localhost/testdb"
+    assert s.CORS_ORIGINS == "http://example.com"
+    assert s.LOG_LEVEL == "debug"
+
+def test_settings_partial_override(monkeypatch):
+    """Test that overriding only some environment variables works correctly."""
+    monkeypatch.setenv("LOG_LEVEL", "warning")
+
+    s = Settings(_env_file=None)
+
+    # Overridden value
+    assert s.LOG_LEVEL == "warning"
+    # Default values should remain
+    assert s.DATABASE_URL == "sqlite+aiosqlite:///./data/sleep.db"
+    assert s.CORS_ORIGINS == "http://localhost:5173"