diff --git a/ndonnx/_logic_in_data/_array.py b/ndonnx/_logic_in_data/_array.py
index 39f430b..a000068 100644
--- a/ndonnx/_logic_in_data/_array.py
+++ b/ndonnx/_logic_in_data/_array.py
@@ -106,11 +106,14 @@ def unwrap_numpy(self) -> np.ndarray:
         """
         return self._data.unwrap_numpy()
 
-    def to_numpy(self) -> np.ndarray:
+    def to_numpy(self) -> np.ndarray | None:
         from warnings import warn
 
         warn("'to_numpy' is deprecated in favor of 'unwrap_numpy'", DeprecationWarning)
-        return self.unwrap_numpy()
+        try:
+            return self.unwrap_numpy()
+        except ValueError:
+            return None
 
     def __getitem__(self, key: GetitemIndex, /) -> Array:
         from ._typed_array import TyArrayBool, TyArrayInteger
diff --git a/ndonnx/_logic_in_data/_build.py b/ndonnx/_logic_in_data/_build.py
index f68b1c9..90fb889 100644
--- a/ndonnx/_logic_in_data/_build.py
+++ b/ndonnx/_logic_in_data/_build.py
@@ -18,13 +18,16 @@ def build(arguments: dict[str, Array], results: dict[str, Array]) -> onnx.ModelP
     mp = spox_build(ins, outs, drop_unused_inputs=True)
 
     metadata = {
-        "schemas": json.dumps(
+        "ndonnx": json.dumps(
             {
-                "arguments": json.loads(_json_schema(arguments)),
-                "results": json.loads(_json_schema(results)),
+                "schemas": {
+                    "arguments": json.loads(_json_schema(arguments)),
+                    "results": json.loads(_json_schema(results)),
+                },
+                # Version for how we organize our metadata in general
+                "metadata_version": "1",
             }
-        ),
-        "ndonnx_schema_version": "1",
+        )
     }
     onnx.helper.set_model_props(mp, metadata)
 
diff --git a/ndonnx/_logic_in_data/_schema.py b/ndonnx/_logic_in_data/_schema.py
index 73425af..66e9656 100644
--- a/ndonnx/_logic_in_data/_schema.py
+++ b/ndonnx/_logic_in_data/_schema.py
@@ -4,38 +4,46 @@
 
 import json
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Any, Literal
+from typing import Any, Literal
 
 import numpy as np
 import onnx
-
-if TYPE_CHECKING:
-    from spox import Var
-    from typing_extensions import Self
-
-    Json = dict[str, "Json"] | list["Json"] | str | int | float | bool | None
-    PrimitiveComponent = Literal[
-        "float16",
-        "float32",
-        "float64",
-        "int8",
-        "int16",
-        "int32",
-        "int64",
-        "uint8",
-        "uint16",
-        "uint32",
-        "uint64",
-        "bool",
-        "str",
-    ]
-    StructComponent = dict[str, "Schema"]
-    Components = dict[str, Var]
+from spox import Var
+from typing_extensions import Self
+
+Json = dict[str, "Json"] | list["Json"] | str | int | float | bool | None
+"""A JSON serializable object."""
+
+PrimitiveComponent = Literal[
+    "float16",
+    "float32",
+    "float64",
+    "int8",
+    "int16",
+    "int32",
+    "int64",
+    "uint8",
+    "uint16",
+    "uint32",
+    "uint64",
+    "bool",
+    "str",
+]
+"""Primitive type with an equivalent type in the ONNX standard."""
+
+StructComponent = dict[str, "Schema"]
+"""A composite type consisting of other ``StructComponents`` or ``PrimitiveTypes``."""
+
+Components = dict[str, Var]
+"""A flattened representation of the components of an array with arbitrary data type."""
 
 
 @dataclass
 class DTypeInfo:
+    """Class returned by ``DType._info`` describing the respective data type."""
+
     defining_library: str
+    # Version of this particular data type
     version: int
     dtype: str
     dtype_state: Json
@@ -43,6 +51,11 @@ class DTypeInfo:
 
 @dataclass
 class Schema:
+    """Schema describing a data type.
+
+    The names are suffixes of the names ultimately used in the model API.
+    """
+
     dtype_info: DTypeInfo
     components: PrimitiveComponent | StructComponent
 
@@ -110,7 +123,15 @@ class Schemas:
 
 def get_schemas(mp: onnx.ModelProto) -> Schemas:
     metadict = {el.key: el.value for el in mp.metadata_props}
-    schema_dict = json.loads(metadict["schemas"])
+    return _get_schemas(metadict)
+
+
+def _get_schemas(metadata: dict[str, str]) -> Schemas:
+    """Get ``Schemas`` from metadata dict.
+
+    This function is factored out from ``get_schemas`` for easier testing.
+    """
+    schema_dict = json.loads(metadata["ndonnx"])["schemas"]
 
     arguments = {k: Schema.from_json(v, 1) for k, v in schema_dict["arguments"].items()}
     results = {k: Schema.from_json(v, 1) for k, v in schema_dict["results"].items()}
diff --git a/ndonnx/_logic_in_data/_typed_array/onnx.py b/ndonnx/_logic_in_data/_typed_array/onnx.py
index 9d5a864..cc3ed00 100644
--- a/ndonnx/_logic_in_data/_typed_array/onnx.py
+++ b/ndonnx/_logic_in_data/_typed_array/onnx.py
@@ -260,7 +260,7 @@ def unwrap_numpy(self) -> np.ndarray:
                 # TODO: Where does the "object" kind come from?
                 # Probably spox; we should have a more predictable
                 # upstream string support.
-                return np_arr
+                return np_arr.astype(str)
 
             # Should not happen
             raise ValueError("unexpected value data type")
diff --git a/tests/schemas/Bool.json b/tests/schemas/Bool.json
new file mode 100644
index 0000000..a36118d
--- /dev/null
+++ b/tests/schemas/Bool.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Float32.json b/tests/schemas/Float32.json
new file mode 100644
index 0000000..ef9d247
--- /dev/null
+++ b/tests/schemas/Float32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float32\", \"dtype_state\": null}, \"components\": \"float32\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float32\", \"dtype_state\": null}, \"components\": \"float32\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Float64.json b/tests/schemas/Float64.json
new file mode 100644
index 0000000..c23a776
--- /dev/null
+++ b/tests/schemas/Float64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float64\", \"dtype_state\": null}, \"components\": \"float64\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float64\", \"dtype_state\": null}, \"components\": \"float64\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Int16.json b/tests/schemas/Int16.json
new file mode 100644
index 0000000..e299e6c
--- /dev/null
+++ b/tests/schemas/Int16.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int16\", \"dtype_state\": null}, \"components\": \"int16\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int16\", \"dtype_state\": null}, \"components\": \"int16\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Int32.json b/tests/schemas/Int32.json
new file mode 100644
index 0000000..cf39d74
--- /dev/null
+++ b/tests/schemas/Int32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int32\", \"dtype_state\": null}, \"components\": \"int32\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int32\", \"dtype_state\": null}, \"components\": \"int32\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Int64.json b/tests/schemas/Int64.json
new file mode 100644
index 0000000..b1d81bf
--- /dev/null
+++ b/tests/schemas/Int64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int64\", \"dtype_state\": null}, \"components\": \"int64\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int64\", \"dtype_state\": null}, \"components\": \"int64\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Int8.json b/tests/schemas/Int8.json
new file mode 100644
index 0000000..dbf3489
--- /dev/null
+++ b/tests/schemas/Int8.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int8\", \"dtype_state\": null}, \"components\": \"int8\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int8\", \"dtype_state\": null}, \"components\": \"int8\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NBool.json b/tests/schemas/NBool.json
new file mode 100644
index 0000000..d5188fd
--- /dev/null
+++ b/tests/schemas/NBool.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NBool\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NBool\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NFloat32.json b/tests/schemas/NFloat32.json
new file mode 100644
index 0000000..f772f68
--- /dev/null
+++ b/tests/schemas/NFloat32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NFloat32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float32\", \"dtype_state\": null}, \"components\": \"float32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NFloat32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float32\", \"dtype_state\": null}, \"components\": \"float32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NFloat64.json b/tests/schemas/NFloat64.json
new file mode 100644
index 0000000..67a1fe6
--- /dev/null
+++ b/tests/schemas/NFloat64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NFloat64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float64\", \"dtype_state\": null}, \"components\": \"float64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NFloat64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Float64\", \"dtype_state\": null}, \"components\": \"float64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NInt16.json b/tests/schemas/NInt16.json
new file mode 100644
index 0000000..19d71a6
--- /dev/null
+++ b/tests/schemas/NInt16.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt16\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int16\", \"dtype_state\": null}, \"components\": \"int16\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt16\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int16\", \"dtype_state\": null}, \"components\": \"int16\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NInt32.json b/tests/schemas/NInt32.json
new file mode 100644
index 0000000..b6cbe4d
--- /dev/null
+++ b/tests/schemas/NInt32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int32\", \"dtype_state\": null}, \"components\": \"int32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int32\", \"dtype_state\": null}, \"components\": \"int32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NInt64.json b/tests/schemas/NInt64.json
new file mode 100644
index 0000000..a7b96fd
--- /dev/null
+++ b/tests/schemas/NInt64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int64\", \"dtype_state\": null}, \"components\": \"int64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int64\", \"dtype_state\": null}, \"components\": \"int64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NInt8.json b/tests/schemas/NInt8.json
new file mode 100644
index 0000000..c37bf38
--- /dev/null
+++ b/tests/schemas/NInt8.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt8\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int8\", \"dtype_state\": null}, \"components\": \"int8\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NInt8\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Int8\", \"dtype_state\": null}, \"components\": \"int8\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NString.json b/tests/schemas/NString.json
new file mode 100644
index 0000000..c7b881f
--- /dev/null
+++ b/tests/schemas/NString.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NString\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"String\", \"dtype_state\": null}, \"components\": \"str\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NString\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"String\", \"dtype_state\": null}, \"components\": \"str\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NUint16.json b/tests/schemas/NUint16.json
new file mode 100644
index 0000000..fcb3819
--- /dev/null
+++ b/tests/schemas/NUint16.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint16\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint16\", \"dtype_state\": null}, \"components\": \"uint16\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint16\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint16\", \"dtype_state\": null}, \"components\": \"uint16\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NUint32.json b/tests/schemas/NUint32.json
new file mode 100644
index 0000000..ebd04cf
--- /dev/null
+++ b/tests/schemas/NUint32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint32\", \"dtype_state\": null}, \"components\": \"uint32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint32\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint32\", \"dtype_state\": null}, \"components\": \"uint32\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NUint64.json b/tests/schemas/NUint64.json
new file mode 100644
index 0000000..fc0a738
--- /dev/null
+++ b/tests/schemas/NUint64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint64\", \"dtype_state\": null}, \"components\": \"uint64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint64\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint64\", \"dtype_state\": null}, \"components\": \"uint64\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/NUint8.json b/tests/schemas/NUint8.json
new file mode 100644
index 0000000..723124f
--- /dev/null
+++ b/tests/schemas/NUint8.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint8\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint8\", \"dtype_state\": null}, \"components\": \"uint8\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"NUint8\", \"dtype_state\": null}, \"components\": {\"data\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint8\", \"dtype_state\": null}, \"components\": \"uint8\"}, \"mask\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Bool\", \"dtype_state\": null}, \"components\": \"bool\"}}}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/String.json b/tests/schemas/String.json
new file mode 100644
index 0000000..dd20a11
--- /dev/null
+++ b/tests/schemas/String.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"String\", \"dtype_state\": null}, \"components\": \"str\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"String\", \"dtype_state\": null}, \"components\": \"str\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Uint16.json b/tests/schemas/Uint16.json
new file mode 100644
index 0000000..d28feb2
--- /dev/null
+++ b/tests/schemas/Uint16.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint16\", \"dtype_state\": null}, \"components\": \"uint16\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint16\", \"dtype_state\": null}, \"components\": \"uint16\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Uint32.json b/tests/schemas/Uint32.json
new file mode 100644
index 0000000..4a51ee6
--- /dev/null
+++ b/tests/schemas/Uint32.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint32\", \"dtype_state\": null}, \"components\": \"uint32\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint32\", \"dtype_state\": null}, \"components\": \"uint32\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Uint64.json b/tests/schemas/Uint64.json
new file mode 100644
index 0000000..9cfd60e
--- /dev/null
+++ b/tests/schemas/Uint64.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint64\", \"dtype_state\": null}, \"components\": \"uint64\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint64\", \"dtype_state\": null}, \"components\": \"uint64\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/schemas/Uint8.json b/tests/schemas/Uint8.json
new file mode 100644
index 0000000..8c3e42e
--- /dev/null
+++ b/tests/schemas/Uint8.json
@@ -0,0 +1,3 @@
+{
+    "ndonnx": "{\"schemas\": {\"arguments\": {\"a\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint8\", \"dtype_state\": null}, \"components\": \"uint8\"}}, \"results\": {\"b\": {\"dtype_info\": {\"defining_library\": \"ndonnx\", \"version\": 1, \"dtype\": \"Uint8\", \"dtype_state\": null}, \"components\": \"uint8\"}}}, \"metadata_version\": \"1\"}"
+}
diff --git a/tests/test_logic_in_data.py b/tests/test_logic_in_data.py
index 1d35915..f88fc7c 100644
--- a/tests/test_logic_in_data.py
+++ b/tests/test_logic_in_data.py
@@ -7,7 +7,7 @@
 
 import ndonnx._logic_in_data as ndx
 from ndonnx._logic_in_data import _dtypes as dtypes
-from ndonnx._logic_in_data._schema import get_schemas
+from ndonnx._logic_in_data._schema import _get_schemas, get_schemas
 
 
 def check_dtype_shape(arr, dtype, shape):
@@ -187,17 +187,60 @@ def test_add_pyscalar_timedelta(op):
     check_dtype_shape(op(arr, scalar), expected_dtype, shape)
 
 
-def test_build():
-    a = ndx.Array(shape=("N",), dtype=ndx.nint64)
-    b = a[0]
+@pytest.mark.parametrize(
+    "dtype",
+    [
+        ndx.int8,
+        ndx.int16,
+        ndx.int32,
+        ndx.int64,
+        ndx.uint8,
+        ndx.uint16,
+        ndx.uint32,
+        ndx.uint64,
+        ndx.float32,
+        ndx.float64,
+        ndx.string,
+        ndx.bool,
+        ndx.nint8,
+        ndx.nint16,
+        ndx.nint32,
+        ndx.nint64,
+        ndx.nuint8,
+        ndx.nuint16,
+        ndx.nuint32,
+        ndx.nuint64,
+        ndx.nfloat32,
+        ndx.nfloat64,
+        ndx.nstring,
+        ndx.nbool,
+    ],
+)
+def test_build(dtype):
+    a = ndx.Array(shape=("N",), dtype=dtype)
+    b = a[0]  # make the build non-trivial
 
     mp = ndx.build({"a": a}, {"b": b})
 
-    schemas = get_schemas(mp)
+    # We must not break backwards compatibility. We test every type we
+    # support that it keeps producing the same schema.
+    import json
+    from pathlib import Path
+
+    fname = Path(__file__).parent / f"schemas/{dtype}.json"
+    with open(fname, "w+") as f:
+        json.dump({el.key: el.value for el in mp.metadata_props}, f, indent=4)
+        f.write("\n")  # Avoid pre-commit complaint about missing new lines
+
+    with open(fname) as f:
+        expected_schemas = _get_schemas(json.load(f))
+    candidate_schemas = get_schemas(mp)
+
+    assert expected_schemas == candidate_schemas
 
     # test json round trip of schema data
-    assert schemas.arguments["a"] == a._data.disassemble()[1]
-    assert schemas.results["b"] == b._data.disassemble()[1]
+    assert candidate_schemas.arguments["a"] == a._data.disassemble()[1]
+    assert candidate_schemas.results["b"] == b._data.disassemble()[1]
 
 
 @pytest.mark.parametrize(