tst: exercise `nitransforms.io.x5.to_filename()

Author: oesteban

nitransforms/linear.py

@@ -285,6 +285,7 @@ def to_x5(self, store_inverse=False, metadata=None):
                 grid=True,
                 size=getattr(reference or {}, "shape", (0, 0, 0)),
                 mapping=reference.affine,
+                coordinates="cartesian",
             )
         kinds = tuple("space" for _ in range(self.ndim)) + ("vector",)
         return X5Transform(

nitransforms/tests/test_linear.py

@@ -265,11 +265,15 @@ def test_Affine_to_x5(tmpdir, store_inverse):
     img_path = Path(tmpdir) / "ref.nii.gz"
     img.to_filename(str(img_path))
 
+    io.x5.to_filename("export1.x5", [node])
+
     aff.reference = img_path
     node = aff.to_x5()
     assert node.domain.grid
     assert node.domain.size == aff.reference.shape
 
+    io.x5.to_filename("export2.x5", [node])
+
 
 def test_mapping_to_x5():
     mats = [