test: add tests for the DependencyNotInstalled exception for xgboost-…

…sampler and gp-sampler

tests/test_samplers/test_gaussian_process.py

@@ -20,9 +20,11 @@
 import pytest
 from numpy.typing import NDArray
 
+import black_it
 from black_it.samplers.gaussian_process import GaussianProcessSampler, _AcquisitionTypes
 from black_it.search_space import SearchSpace
 from tests.utils.base import no_gpy_installed, no_python311_for_gpy
+from tests.utils.extras_tester import generic_test_import_error
 
 pytestmark = [no_python311_for_gpy, no_gpy_installed]  # noqa
 
@@ -137,3 +139,16 @@ def test_gaussian_process_sample_wrong_acquisition() -> None:
         f"got {wrong_acquisition}",
     ):
         GaussianProcessSampler(4, acquisition=wrong_acquisition)
+
+
+def test_dependency_not_installed_error() -> None:
+    """Test the "DependencyNotInstalled" exception in case the dependencies of the component are not installed."""
+    generic_test_import_error(
+        module_obj=black_it.samplers.gaussian_process,
+        import_error_global_variable_name="_GPY_IMPORT_ERROR",
+        component_initializer=lambda: GaussianProcessSampler(4),
+        expected_message_pattern=(
+            r"Cannot import package 'GPy', required by component GaussianProcessSampler\. "
+            r"To solve the issue, you can install the extra 'gp-sampler': pip install black-it\[gp-sampler\]"
+        ),
+    )

tests/test_samplers/test_xgboost.py

@@ -18,6 +18,7 @@
 
 import numpy as np
 
+import black_it
 from black_it.calibrator import Calibrator
 from black_it.loss_functions.msm import MethodOfMomentsLoss
 from black_it.samplers.halton import HaltonSampler
@@ -26,6 +27,7 @@
 
 from ..fixtures.test_models import BH4  # type: ignore
 from ..utils.base import no_xgboost_installed
+from ..utils.extras_tester import generic_test_import_error
 
 pytestmark = no_xgboost_installed  # noqa
 
@@ -136,3 +138,16 @@ def test_clip_losses() -> None:
     assert (
         y2 == np.array([0.0, MIN_FLOAT32 + EPS_FLOAT32, MAX_FLOAT32 - EPS_FLOAT32])
     ).all()
+
+
+def test_dependency_not_installed_error() -> None:
+    """Test the "DependencyNotInstalled" exception in case the dependencies of the component are not installed."""
+    generic_test_import_error(
+        module_obj=black_it.samplers.xgboost,
+        import_error_global_variable_name="_XGBOOST_IMPORT_ERROR",
+        component_initializer=lambda: XGBoostSampler(4),
+        expected_message_pattern=(
+            r"Cannot import package 'xgboost', required by component XGBoostSampler. "
+            r"To solve the issue, you can install the extra 'xgboost-sampler': pip install black-it\[xgboost-sampler\]"
+        ),
+    )

tests/utils/extras_tester.py

@@ -0,0 +1,73 @@
+# Black-box ABM Calibration Kit (Black-it)
+# Copyright (C) 2021-2023 Banca d'Italia
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+"""Test utilities to test the correct working of the extras mechanism."""
+import contextlib
+from types import ModuleType
+from typing import Any, Callable, Generator
+
+import pytest
+
+from black_it._load_dependency import DependencyNotInstalled
+
+
+@contextlib.contextmanager
+def _change_variable_value(
+    module_obj: ModuleType, variable_name: str, value: Any
+) -> Generator[None, None, None]:
+    """Change, temporarily, the value of a variable in a module."""
+    old_value = getattr(module_obj, variable_name)
+    setattr(module_obj, variable_name, value)
+    yield
+    setattr(module_obj, variable_name, old_value)
+
+
+def generic_test_import_error(
+    module_obj: ModuleType,
+    import_error_global_variable_name: str,
+    component_initializer: Callable,
+    expected_message_pattern: str,
+) -> None:
+    """
+    Test that the correct exception is raised when a dependency is not installed.
+
+    This function is an utility testing function to test that the correct exception is raised when a dependency is not
+      installed.
+
+    It assumes the module under testing, associated to some Black-it component (e.g. loss, sampler, etc.), has a global
+      variable named import_error_global_variable_name, which is set to None if the dependency is installed, or to a
+      DependencyNotInstalled exception if the dependency is not installed. This convention is the one used in the
+      Black-it code.
+
+    For example, samplers.xgboost has a global variable named _XGBOOST_IMPORT_ERROR, which is set to None if the xgboost
+      package is installed, or to an DependencyNotInstalled if the xgboost package is not installed. Then, during the
+      initialization of XGBoostSampler, the value of the _XGBOOST_IMPORT_ERROR variable is checked, and if it is not
+      None, an exception is raised.
+
+    This test function checks that the correct exception is raised when the import_error_global_variable_name variable
+      is set to None and we try to initialize the Black-it component.
+
+    Args:
+        module_obj: the module object to test
+        import_error_global_variable_name: the name of the global variable in the module object
+        component_initializer: the function to call to initialize the component under testing
+        expected_message_pattern: the pattern of the expected exception message
+    """
+    with _change_variable_value(
+        module_obj, import_error_global_variable_name, ImportError("fake error")
+    ):
+        with pytest.raises(DependencyNotInstalled, match=expected_message_pattern):
+            component_initializer()