test: cover optional dependencies

src/conformal_tights/_darts_forecaster.py

@@ -35,8 +35,8 @@
             _LikelihoodMixin,
         )
     except ImportError:
-        FUTURE_LAGS_TYPE = int
-        LAGS_TYPE = list[int]
+        FUTURE_LAGS_TYPE = tuple[int, int] | list[int] | dict[str, tuple[int, int] | list[int]]
+        LAGS_TYPE = int | list[int] | dict[str, int | list[int]]
 
         class TimeSeries: ...
 

tests/test_optional_dependencies.py

@@ -0,0 +1,30 @@
+"""Test this package's optional dependencies."""
+
+import sys
+from unittest.mock import patch
+
+import pytest
+
+
+@pytest.mark.parametrize("optional_dependency", ["darts", "pandas"])
+def test_optional_dependencies(optional_dependency: str) -> None:
+    """Test that we get an expected error when an optional dependency are not available."""
+    # Prevent the optional dependency from being loaded.
+    with patch.dict("sys.modules", {optional_dependency: None}):
+        # Unload Conformal Tights.
+        mods_to_unload = [mod for mod in sys.modules if mod.startswith("conformal_tights")]
+        for mod in mods_to_unload:
+            del sys.modules[mod]
+
+        # Reload Conformal Tights now that the selected optional dependency is not available.
+        from conformal_tights import ConformalCoherentQuantileRegressor, DartsForecaster
+
+        # Test that we raise the appropriate error.
+        conformal_predictor = ConformalCoherentQuantileRegressor()
+        with pytest.raises(ImportError, match=f".*install.*{optional_dependency}.*"):
+            _ = DartsForecaster(model=conformal_predictor)
+
+        # Unload Conformal Tights again.
+        mods_to_unload = [mod for mod in sys.modules if mod.startswith("conformal_tights")]
+        for mod in mods_to_unload:
+            del sys.modules[mod]