diff --git a/src/numpydantic/serialization.py b/src/numpydantic/serialization.py
index d9a73e0..2fda25c 100644
--- a/src/numpydantic/serialization.py
+++ b/src/numpydantic/serialization.py
@@ -9,6 +9,7 @@ from typing import TYPE_CHECKING, Any, Callable, Iterable, TypeVar, Union
 from pydantic_core import SchemaSerializer
 from pydantic_core.core_schema import (
     SerializationInfo,
+    any_schema,
     plain_serializer_function_ser_schema,
 )
 
@@ -75,9 +76,11 @@ def postprocess_json(
 
 
 pydantic_serializer = SchemaSerializer(
-    plain_serializer_function_ser_schema(
-        jsonize_array, when_used="json", info_arg=True
-    ),
+    any_schema(
+        serialization=plain_serializer_function_ser_schema(
+            jsonize_array, when_used="json", info_arg=True
+        )
+    )
 )
 """
 A generic serializer that can be applied to interface proxies et al as
diff --git a/src/numpydantic/testing/cases.py b/src/numpydantic/testing/cases.py
index d0f44ee..73b401c 100644
--- a/src/numpydantic/testing/cases.py
+++ b/src/numpydantic/testing/cases.py
@@ -225,34 +225,36 @@ All the interface cases
 """
 
 
-DTYPE_AND_SHAPE_CASES = merged_product(SHAPE_CASES, DTYPE_CASES)
+DTYPE_AND_SHAPE_CASES = list(merged_product(SHAPE_CASES, DTYPE_CASES))
 """
 Merged product of dtype and shape cases
 """
-DTYPE_AND_SHAPE_CASES_PASSING = merged_product(
-    SHAPE_CASES, DTYPE_CASES, conditions={"passes": True}
+DTYPE_AND_SHAPE_CASES_PASSING = list(
+    merged_product(SHAPE_CASES, DTYPE_CASES, conditions={"passes": True})
 )
 """
 Merged product of dtype and shape cases that are valid
 """
 
-DTYPE_AND_INTERFACE_CASES = merged_product(INTERFACE_CASES, DTYPE_CASES)
+DTYPE_AND_INTERFACE_CASES = list(merged_product(INTERFACE_CASES, DTYPE_CASES))
 """
 Merged product of dtype and interface cases
 """
-DTYPE_AND_INTERFACE_CASES_PASSING = merged_product(
-    INTERFACE_CASES, DTYPE_CASES, conditions={"passes": True}
+DTYPE_AND_INTERFACE_CASES_PASSING = list(
+    merged_product(INTERFACE_CASES, DTYPE_CASES, conditions={"passes": True})
 )
 """
 Merged product of dtype and interface cases that pass
 """
 
-ALL_CASES = merged_product(SHAPE_CASES, DTYPE_CASES, INTERFACE_CASES)
+ALL_CASES = list(merged_product(SHAPE_CASES, DTYPE_CASES, INTERFACE_CASES))
 """
 Merged product of all cases - dtype, shape, and interface
 """
-ALL_CASES_PASSING = merged_product(
-    SHAPE_CASES, DTYPE_CASES, INTERFACE_CASES, conditions={"passes": True}
+ALL_CASES_PASSING = list(
+    merged_product(
+        SHAPE_CASES, DTYPE_CASES, INTERFACE_CASES, conditions={"passes": True}
+    )
 )
 """
 Merged product of all cases, but only those that pass
diff --git a/src/numpydantic/testing/helpers.py b/src/numpydantic/testing/helpers.py
index b337e7d..37d8f1e 100644
--- a/src/numpydantic/testing/helpers.py
+++ b/src/numpydantic/testing/helpers.py
@@ -129,7 +129,7 @@ class ValidationCase(BaseModel):
     """
     Dtype to use in computed annotation used to validate against
     """
-    shape: Tuple[int, ...] = (10, 10, 2, 2)
+    shape: Tuple[int, ...] = (10, 10, 2, 3)
     """Shape of the array to validate"""
     dtype: Union[Type, np.dtype] = float
     """Dtype of the array to validate"""
diff --git a/tests/test_interface/test_interfaces.py b/tests/test_interface/test_interfaces.py
index cd113bf..a2eaf82 100644
--- a/tests/test_interface/test_interfaces.py
+++ b/tests/test_interface/test_interfaces.py
@@ -14,6 +14,11 @@ from zarr.core import Array as ZarrArray
 
 from numpydantic import NDArray
 from numpydantic.interface import Interface, InterfaceMark, MarkedJson
+from numpydantic.testing.cases import (
+    ALL_CASES_PASSING,
+    DTYPE_AND_INTERFACE_CASES_PASSING,
+    INTERFACE_CASES,
+)
 from numpydantic.testing.helpers import ValidationCase
 
 
@@ -40,6 +45,26 @@ def _test_roundtrip(source: BaseModel, target: BaseModel):
     assert target.array.dtype == source.array.dtype
 
 
+@pytest.mark.parametrize(
+    "interface",
+    [
+        pytest.param(i, marks=getattr(pytest.mark, i.interface.interface.name))
+        for i in INTERFACE_CASES
+    ],
+)
+@pytest.mark.parametrize(
+    "cases", [ALL_CASES_PASSING, DTYPE_AND_INTERFACE_CASES_PASSING]
+)
+def test_cases_include_all_interfaces(interface: ValidationCase, cases):
+    """
+    Test our test cases - we should hit all interfaces in the common "test all" fixtures
+    """
+    cases = list(cases)
+    assert any(
+        [case.interface is interface.interface for case in cases]
+    ), f"Interface case unused in general test cases: {interface.interface}"
+
+
 def test_dunder_len(interface_cases, tmp_output_dir_func):
     """
     Each interface or proxy type should support __len__
@@ -177,7 +202,8 @@ def test_roundtrip_from_extra(dtype_by_interface, tmp_output_dir_func):
 @pytest.mark.serialization
 def test_roundtrip_from_union(dtype_by_interface, tmp_output_dir_func):
     """
-    Arrays can be dumped when they are specified along with a union of another type field
+    Arrays can be dumped when they are specified along with a
+    union of another type field
     """
 
     class Model(BaseModel):
@@ -209,16 +235,3 @@ def test_roundtrip_from_generic(dtype_by_interface, tmp_output_dir_func):
     dumped = instance.model_dump_json(round_trip=True)
     roundtripped = Model.model_validate_json(dumped)
     _test_roundtrip(instance, roundtripped)
-
-
-@pytest.mark.serialization
-def test_roundtrip_from_any(dtype_by_interface, tmp_output_dir_func):
-    """
-    We can roundtrip from an AnyType
-    Args:
-        dtype_by_interface:
-        tmp_output_dir_func:
-
-    Returns:
-
-    """