add tests for codecjson typeguard

Author: d-v-b

tests/test_abc/__init__.py

@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+from zarr.abc.codec import _check_codecjson_v2
+
+
+def test_check_codecjson_v2_valid() -> None:
+    """
+    Test that the _check_codecjson_v2 function works
+    """
+    assert _check_codecjson_v2({"id": "gzip"})
+    assert not _check_codecjson_v2({"id": 10})
+    assert not _check_codecjson_v2([10, 11])