test: add ndarray type test

tests/patterns/ndarray_type_test.py

@@ -0,0 +1,32 @@
+import asdf
+import numpy as np
+from asdf.extension import Extension
+
+from asdf_pydantic import AsdfPydanticConverter, AsdfPydanticModel
+
+
+class Data(AsdfPydanticModel):
+    _tag = "asdf://asdf-pydantic/examples/tags/data-1.0.0"
+    array: np.ndarray
+
+
+def setup_module():
+    AsdfPydanticConverter.add_models(Data)
+
+    class TestExtension(Extension):
+        extension_uri = "asdf://asdf-pydantic/examples/extensions/test-1.0.0"
+
+        converters = [AsdfPydanticConverter()]  # type: ignore
+        tags = [*AsdfPydanticConverter().tags]  # type: ignore
+
+    asdf.get_config().add_extension(TestExtension())
+
+
+def test_can_write_with_subclass_model(tmp_path):
+    data = Data(array=np.array([1, 2, 3]))
+
+    af = asdf.AsdfFile({"data": data})
+    af.write_to(tmp_path / "test.asdf")
+
+    with asdf.open(tmp_path / "test.asdf", lazy_load=False) as af:
+        assert isinstance(af["data"], Data)