Lazy load optional dependencies

src/harmonica/_forward/ellipsoids/ellipsoids.py

@@ -16,11 +16,6 @@
 
 from ..utils import get_rotation_matrix
 
-try:
-    import pyvista
-except ImportError:  # pragma: no cover
-    pyvista = None
-
 
 class Ellipsoid:
     """
@@ -313,12 +308,9 @@ def to_pyvista(self, **kwargs):
         ellipsoid : pyvista.PolyData
             A PyVista's parametric ellipsoid.
         """
-        if pyvista is None:
-            msg = (
-                "Missing optional dependency 'pyvista' required for "
-                "exporting ellipsoids to PyVista."
-            )
-            raise ImportError(msg)
+        # Lazy load optional dependency
+        import pyvista  # noqa: PLC0415
+
         ellipsoid = pyvista.ParametricEllipsoid(
             xradius=self.a, yradius=self.b, zradius=self.c, **kwargs
         )

src/harmonica/_forward/utils.py

@@ -14,12 +14,6 @@
 from numba import jit
 from scipy.spatial.transform import Rotation
 
-# Attempt to import numba_progress
-try:
-    from numba_progress import ProgressBar
-except ImportError:  # pragma: no cover
-    ProgressBar = None
-
 
 def distance(point_p, point_q, coordinate_system="cartesian", ellipsoid=None):
     """
@@ -384,12 +378,17 @@ def initialize_progressbar(total, use_progressbar):
     # Return None if progressbar is not desired
     if not use_progressbar:
         return contextlib.nullcontext()
-    # Raise error if numba_progress is not installed
-    if ProgressBar is None:
-        msg = (
-            "Missing optional dependency 'numba_progress' required if progressbar=True"
-        )
-        raise ImportError(msg)
+
+    # Lazily load optional dependency
+    try:
+        from numba_progress import ProgressBar  # noqa: PLC0415
+    except ImportError as original:  # pragma: nocover
+        error = ImportError(
+            "Cannot import the optional dependency 'numba_progress'. "
+            "It must be installed to be able to show a progressbar."
+        )  # pragma: nocover
+        raise error from original  # pragma: nocover
+
     return ProgressBar(total=total)
 
 

src/harmonica/visualization/_prism.py

@@ -10,13 +10,6 @@
 
 import numpy as np
 
-try:
-    import pyvista
-except ImportError:  # pragma: no cover
-    pyvista = None
-else:
-    import vtk
-
 
 def prism_to_pyvista(prisms, properties=None):
     """
@@ -71,12 +64,10 @@ def prism_to_pyvista(prisms, properties=None):
        >>> pv_grid.plot() # doctest: +SKIP
 
     """
-    # Check if pyvista are installed
-    if pyvista is None:
-        msg = (
-            "Missing optional dependency 'pyvista' required for building pyvista grids."
-        )
-        raise ImportError(msg)
+    # Lazily import optional dependencies
+    import pyvista  # noqa: PLC0415
+    import vtk  # noqa: PLC0415
+
     # Get prisms and number of prisms
     prisms = np.atleast_2d(prisms)
     n_prisms = prisms.shape[0]

test/ellipsoids/test_ellipsoids.py

@@ -9,7 +9,6 @@
 """
 
 import re
-from unittest.mock import patch
 
 import numpy as np
 import pytest
@@ -212,14 +211,6 @@ def ellipsoid(self):
         center = (43.0, -72.0, 105)
         return Ellipsoid(a, b, c, yaw=yaw, pitch=pitch, roll=roll, center=center)
 
-    @patch("harmonica._forward.ellipsoids.ellipsoids.pyvista", None)
-    def test_pyvista_missing_error(self, ellipsoid):
-        """
-        Check if error is raised when pyvista is not installed.
-        """
-        with pytest.raises(ImportError):
-            ellipsoid.to_pyvista()
-
     def test_pyvista_object(self, ellipsoid):
         """
         Check if method works as expected.

test/test_forward_utils.py

@@ -8,8 +8,6 @@
 Test utils functions for forward modelling.
 """
 
-from unittest.mock import patch
-
 import boule as bl
 import numpy as np
 import numpy.testing as npt
@@ -131,16 +129,3 @@ def test_initialize_progressbar(use_progressbar):
             assert isinstance(progress_proxy, ProgressBar)
         else:
             assert progress_proxy is None
-
-
-@patch("harmonica._forward.utils.ProgressBar", None)
-@pytest.mark.parametrize("use_progressbar", [True, False])
-def test_initialize_progressbar_import_error(use_progressbar):
-    """Test if it raises ImportError when numba_progress is missing."""
-    if use_progressbar:
-        with pytest.raises(ImportError):  # noqa: SIM117
-            with initialize_progressbar(3, use_progressbar) as progress_proxy:
-                pass  # pragma: no cover (won't reach this code)
-    else:
-        with initialize_progressbar(3, use_progressbar) as progress_proxy:
-            assert progress_proxy is None

test/test_prism.py

@@ -9,7 +9,6 @@
 """
 
 import re
-from unittest.mock import patch
 
 import bordado as bd
 import numpy as np
@@ -377,18 +376,6 @@ def test_progress_bar(self, coordinates, prisms, densities, field):
         )
         npt.assert_allclose(result_progress_true, result_progress_false)
 
-    @patch("harmonica._forward.utils.ProgressBar", None)
-    def test_numba_progress_missing_error(self, coordinates, prisms, densities):
-        """
-        Check if error is raised when progresbar=True and numba_progress
-        package is not installed.
-        """
-        # Check if error is raised
-        with pytest.raises(ImportError):
-            prism_gravity(
-                coordinates, prisms, densities, field="potential", progressbar=True
-            )
-
 
 class TestSingularPoints:
     """

test/test_prism_layer.py

@@ -9,7 +9,6 @@
 """
 
 import re
-from unittest.mock import patch
 
 import bordado as bd
 import numpy as np
@@ -420,24 +419,6 @@ def test_progress_bar(dummy_layer):
     npt.assert_allclose(result_progress_true, result_progress_false)
 
 
-@patch("harmonica._forward.utils.ProgressBar", None)
-def test_numba_progress_missing_error(dummy_layer):
-    """
-    Check if error is raised when progressbar=True and numba_progress package
-    is not installed.
-    """
-    coordinates = bd.grid_coordinates(
-        (1, 3, 7, 10), spacing=1, non_dimensional_coords=30.0
-    )
-    (easting, northing), surface, reference, density = dummy_layer
-    layer = prism_layer(
-        (easting, northing), surface, reference, properties={"density": density}
-    )
-    # Check if error is raised
-    with pytest.raises(ImportError):
-        layer.prism_layer.gravity(coordinates, field="g_z", progressbar=True)
-
-
 def test_gravity_discarded_thin_prisms(dummy_layer):
     """
     Check if gravity of prism layer after discarding thin prisms is correct.

test/test_tesseroid.py

@@ -9,7 +9,6 @@
 """
 
 import re
-from unittest.mock import patch
 
 import bordado as bd
 import boule
@@ -808,15 +807,3 @@ def test_progress_bar(self, coordinates, tesseroids, densities, field):
             coordinates, tesseroids, densities, field=field, progressbar=False
         )
         npt.assert_allclose(result_progress_true, result_progress_false)
-
-    @patch("harmonica._forward.utils.ProgressBar", None)
-    def test_numba_progress_missing_error(self, coordinates, tesseroids, densities):
-        """
-        Check if error is raised when progresbar=True and numba_progress
-        package is not installed.
-        """
-        # Check if error is raised
-        with pytest.raises(ImportError):
-            tesseroid_gravity(
-                coordinates, tesseroids, densities, field="potential", progressbar=True
-            )

test/test_tesseroid_layer.py

@@ -9,7 +9,6 @@
 """
 
 import warnings
-from unittest.mock import patch
 
 import bordado as bd
 import boule
@@ -493,24 +492,6 @@ def test_progress_bar(dummy_layer):
     npt.assert_allclose(result_progress_true, result_progress_false)
 
 
-@patch("harmonica._forward.utils.ProgressBar", None)
-def test_numba_progress_missing_error(dummy_layer):
-    """
-    Check if error is raised when progressbar=True and numba_progress package
-    is not installed.
-    """
-    (longitude, latitude), surface, reference, density = dummy_layer
-    coordinates = bd.grid_coordinates(
-        (-10, 10, -10, 10), spacing=7, non_dimensional_coords=(surface[0] + 10e3)
-    )
-    layer = tesseroid_layer(
-        (longitude, latitude), surface, reference, properties={"density": density}
-    )
-    # Check if error is raised
-    with pytest.raises(ImportError):
-        layer.tesseroid_layer.gravity(coordinates, field="g_z", progressbar=True)
-
-
 def test_gravity_discarded_thin_tesseroids(dummy_layer):
     """
     Check if gravity of tesseroid layer after discarding thin tesseroids is correct.

test/test_tesseroid_variable_density.py

@@ -8,8 +8,6 @@
 Test forward modelling for tesseroids with variable density.
 """
 
-from unittest.mock import patch
-
 import bordado as bd
 import numpy as np
 import numpy.testing as npt
@@ -569,15 +567,3 @@ def test_progress_bar(self, coordinates, tesseroids, densities, field):
             coordinates, tesseroids, densities, field=field, progressbar=False
         )
         npt.assert_allclose(result_progress_true, result_progress_false)
-
-    @patch("harmonica._forward.utils.ProgressBar", None)
-    def test_numba_progress_missing_error(self, coordinates, tesseroids, densities):
-        """
-        Check if error is raised when progresbar=True and numba_progress
-        package is not installed.
-        """
-        # Check if error is raised
-        with pytest.raises(ImportError):
-            tesseroid_gravity(
-                coordinates, tesseroids, densities, field="potential", progressbar=True
-            )

test/test_visualizations.py

@@ -9,7 +9,6 @@
 """
 
 import re
-from unittest.mock import patch
 
 import numpy as np
 import numpy.testing as npt
@@ -24,17 +23,6 @@
     pyvista = None
 
 
-@patch("harmonica.visualization._prism.pyvista", None)
-def test_prism_to_pyvista_missing_pyvista():
-    """
-    Check error raise after calling prism_to_pyvista when pyvista is missing.
-    """
-    prism = [0, 1, 0, 1, 0, 1]
-    with pytest.raises(ImportError) as exception:
-        prism_to_pyvista(prism)
-    assert "'pyvista'" in str(exception.value)
-
-
 @pytest.fixture(name="prisms")
 def fixture_prisms():
     """
@@ -124,13 +112,3 @@ def test_prism_to_pyvista_error_2d_property(prisms, density):
     )
     with pytest.raises(ValueError, match=msg):
         prism_to_pyvista(prisms, properties={name: density_2d})
-
-
-@patch("harmonica.visualization._prism.pyvista", None)
-def test_prisms_pyvista_missing_error(prisms, density):
-    """
-    Check if prism_to_pyvista raises error if pyvista is missing.
-    """
-    # Check if error is raised
-    with pytest.raises(ImportError):
-        prism_to_pyvista(prisms, properties={"density": density})