test: cover x5.from_filename

Author: oesteban

nitransforms/tests/test_x5.py

@@ -1,7 +1,8 @@
 import numpy as np
+import pytest
 from h5py import File as H5File
 
-from ..io.x5 import X5Transform, X5Domain, to_filename
+from ..io.x5 import X5Transform, X5Domain, to_filename, from_filename
 
 
 def test_x5_transform_defaults():
@@ -39,3 +40,38 @@ def test_to_filename(tmp_path):
         assert "0" in grp
         assert grp["0"].attrs["Type"] == "linear"
         assert grp["0"].attrs["ArrayLength"] == 1
+
+
+def test_from_filename_roundtrip(tmp_path):
+    domain = X5Domain(grid=False, size=(5, 5, 5), mapping=np.eye(4))
+    node = X5Transform(
+        type="linear",
+        transform=np.eye(4),
+        dimension_kinds=("space", "space", "space", "vector"),
+        domain=domain,
+        metadata={"foo": "bar"},
+        inverse=np.eye(4),
+    )
+    fname = tmp_path / "test.x5"
+    to_filename(fname, [node])
+
+    x5_list = from_filename(fname)
+    assert len(x5_list) == 1
+    x5 = x5_list[0]
+    assert x5.type == node.type
+    assert np.allclose(x5.transform, node.transform)
+    assert x5.dimension_kinds == list(node.dimension_kinds)
+    assert x5.domain.grid == domain.grid
+    assert x5.domain.size == tuple(domain.size)
+    assert np.allclose(x5.domain.mapping, domain.mapping)
+    assert x5.metadata == node.metadata
+    assert np.allclose(x5.inverse, node.inverse)
+
+
+def test_from_filename_invalid(tmp_path):
+    fname = tmp_path / "invalid.h5"
+    with H5File(fname, "w") as f:
+        f.attrs["Format"] = "NOTX5"
+
+    with pytest.raises(ValueError):
+        from_filename(fname)