fix: fixed error types and increased test coverage

Author: oesteban

nitransforms/base.py

@@ -267,6 +267,9 @@ def apply(
             self.reference if reference is None else SpatialReference.factory(reference)
         )
 
+        if _ref is None:
+            raise TransformError("Cannot apply transform without reference")
+
         if isinstance(spatialimage, (str, Path)):
             spatialimage = _nbload(str(spatialimage))
 

nitransforms/nonlinear.py

@@ -153,14 +153,15 @@ def __init__(self, coefficients, reference=None, order=3):
 
     def to_field(self, reference=None, dtype="float32"):
         """Generate a displacements deformation field from this B-Spline field."""
-        reference = _ensure_image(reference)
-        _ref = self.reference if reference is None else SpatialReference.factory(reference)
+        _ref = (
+            self.reference if reference is None else
+            ImageGrid(_ensure_image(reference))
+        )
         if _ref is None:
-            raise ValueError("A reference must be defined")
+            raise TransformError("A reference must be defined")
 
         ndim = self._coeffs.shape[-1]
 
-        # If locations to be interpolated are on a grid, use faster tensor-bspline calculation
         if self._weights is None:
             self._weights = grid_bspline_weights(_ref, self._knots)
 
@@ -185,21 +186,17 @@ def apply(
     ):
         """Apply a B-Spline transform on input data."""
 
-        if reference is not None:
-            reference = _ensure_image(reference)
-
         _ref = (
-            self.reference if reference is None else SpatialReference.factory(reference)
+            self.reference if reference is None else
+            SpatialReference.factory(_ensure_image(reference))
         )
-
-        if isinstance(spatialimage, (str, Path)):
-            spatialimage = _nbload(str(spatialimage))
+        spatialimage = _ensure_image(spatialimage)
 
         # If locations to be interpolated are not on a grid, run map()
         if not isinstance(_ref, ImageGrid):
             return super().apply(
                 spatialimage,
-                reference=reference,
+                reference=_ref,
                 order=order,
                 mode=mode,
                 cval=cval,
@@ -208,7 +205,7 @@ def apply(
             )
 
         # If locations to be interpolated are on a grid, generate a displacements field
-        return self.to_field().apply(
+        return self.to_field(reference=reference).apply(
             spatialimage,
             reference=reference,
             order=order,

nitransforms/tests/test_nonlinear.py

@@ -41,7 +41,7 @@ def test_itk_disp_load(size):
         ITKDisplacementsField.from_image(nb.Nifti1Image(np.zeros(size), np.eye(4), None))
 
 
-@pytest.mark.parametrize("size", [(20, 20, 20), (20, 20, 20, 2, 3)])
+@pytest.mark.parametrize("size", [(20, 20, 20), (20, 20, 20, 2, 3), (20, 20, 20, 1, 4)])
 def test_displacements_bad_sizes(size):
     """Checks field sizes."""
     with pytest.raises(TransformError):
@@ -58,6 +58,48 @@ def test_itk_disp_load_intent():
     assert field.header.get_intent()[0] == "vector"
 
 
+def test_displacements_init():
+    DisplacementsFieldTransform(
+        np.zeros((10, 10, 10, 3)),
+        reference=nb.Nifti1Image(np.zeros((10, 10, 10, 3)), np.eye(4), None),
+    )
+
+    with pytest.raises(TransformError):
+        DisplacementsFieldTransform(np.zeros((10, 10, 10, 3)))
+    with pytest.raises(TransformError):
+        DisplacementsFieldTransform(
+            np.zeros((10, 10, 10, 3)),
+            reference=np.zeros((10, 10, 10, 3)),
+        )
+
+
+def test_bsplines_init():
+    with pytest.raises(TransformError):
+        BSplineFieldTransform(
+            nb.Nifti1Image(np.zeros((10, 10, 10, 4)), np.eye(4), None),
+            reference=nb.Nifti1Image(np.zeros((10, 10, 10)), np.eye(4), None),
+        )
+
+
+def test_bsplines_references(testdata_path):
+    with pytest.raises(TransformError):
+        BSplineFieldTransform(
+            testdata_path / "someones_bspline_coefficients.nii.gz"
+        ).to_field()
+
+    with pytest.raises(TransformError):
+        BSplineFieldTransform(
+            testdata_path / "someones_bspline_coefficients.nii.gz"
+        ).apply(testdata_path / "someones_anatomy.nii.gz")
+
+    BSplineFieldTransform(
+        testdata_path / "someones_bspline_coefficients.nii.gz"
+    ).apply(
+        testdata_path / "someones_anatomy.nii.gz",
+        reference=testdata_path / "someones_anatomy.nii.gz"
+    )
+
+
 @pytest.mark.parametrize("image_orientation", ["RAS", "LAS", "LPS", "oblique"])
 @pytest.mark.parametrize("sw_tool", ["itk", "afni"])
 @pytest.mark.parametrize("axis", [0, 1, 2, (0, 1), (1, 2), (0, 1, 2)])