Fix ensembles to have an empty params_to_tune (#432)

CHANGELOG.md

@@ -38,6 +38,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix forecast visualization with `horizon=1` ([#426](https://github.com/etna-team/etna/pull/426))
 - Set upper bound `<2` on numpy version ([#431](https://github.com/etna-team/etna/pull/431))
 - 
+- Fix `VotingEnsemble`, `StackingEnsemble`, `DirectEnsemble` have a valid `params_to_tune` that returns empty dict ([#432](https://github.com/etna-team/etna/pull/432))
 - Fix passing custom model to `STLTransform` ([#412](https://github.com/etna-team/etna/pull/412))
 - 
 - Update `TSDataset.describe`, `TSDataset.info` to exclude target intervals and target components in `num_exogs` ([#405](https://github.com/etna-team/etna/pull/405))

etna/ensembles/direct_ensemble.py

@@ -176,11 +176,11 @@ def _predict(
     def params_to_tune(self) -> Dict[str, BaseDistribution]:
         """Get hyperparameter grid to tune.
 
-        Not implemented for this class.
+        Currently, returns empty dict, but could have a proper implementation in the future.
 
         Returns
         -------
         :
             Grid with hyperparameters.
         """
-        raise NotImplementedError(f"{self.__class__.__name__} doesn't support this method!")
+        return {}

etna/ensembles/stacking_ensemble.py

@@ -281,11 +281,11 @@ def _predict(
     def params_to_tune(self) -> Dict[str, BaseDistribution]:
         """Get hyperparameter grid to tune.
 
-        Not implemented for this class.
+        Currently, returns empty dict, but could have a proper implementation in the future.
 
         Returns
         -------
         :
             Grid with hyperparameters.
         """
-        raise NotImplementedError(f"{self.__class__.__name__} doesn't support this method!")
+        return {}

etna/ensembles/voting_ensemble.py

@@ -235,11 +235,11 @@ def _predict(
     def params_to_tune(self) -> Dict[str, BaseDistribution]:
         """Get hyperparameter grid to tune.
 
-        Not implemented for this class.
+        Currently, returns empty dict, but could have a proper implementation in the future.
 
         Returns
         -------
         :
             Grid with hyperparameters.
         """
-        raise NotImplementedError(f"{self.__class__.__name__} doesn't support this method!")
+        return {}

tests/test_ensembles/test_direct_ensemble.py

@@ -206,9 +206,9 @@ def test_predict_with_return_components_fails(example_tsds, direct_ensemble_pipe
         direct_ensemble_pipeline.predict(ts=example_tsds, return_components=True)
 
 
-def test_params_to_tune_not_implemented(direct_ensemble_pipeline):
-    with pytest.raises(NotImplementedError, match="DirectEnsemble doesn't support this method"):
-        _ = direct_ensemble_pipeline.params_to_tune()
+def test_params_to_tune(direct_ensemble_pipeline):
+    result = direct_ensemble_pipeline.params_to_tune()
+    assert result == {}
 
 
 @pytest.mark.parametrize("n_jobs", (1, 5))

tests/test_ensembles/test_stacking_ensemble.py

@@ -453,6 +453,6 @@ def test_ts_with_segment_named_target(
         assert isinstance(df, pd.DataFrame)
 
 
-def test_params_to_tune_not_implemented(stacking_ensemble_pipeline):
-    with pytest.raises(NotImplementedError, match="StackingEnsemble doesn't support this method"):
-        _ = stacking_ensemble_pipeline.params_to_tune()
+def test_params_to_tune(stacking_ensemble_pipeline):
+    result = stacking_ensemble_pipeline.params_to_tune()
+    assert result == {}

tests/test_ensembles/test_voting_ensemble.py

@@ -310,6 +310,6 @@ def test_predict_with_return_components_fails(example_tsds, voting_ensemble_naiv
         voting_ensemble_naive.predict(ts=example_tsds, return_components=True)
 
 
-def test_params_to_tune_not_implemented(voting_ensemble_pipeline):
-    with pytest.raises(NotImplementedError, match="VotingEnsemble doesn't support this method"):
-        _ = voting_ensemble_pipeline.params_to_tune()
+def test_params_to_tune(voting_ensemble_pipeline):
+    result = voting_ensemble_pipeline.params_to_tune()
+    assert result == {}