diff --git a/tests/test_utils_jsonext.py b/tests/test_utils_jsonext.py
new file mode 100644
index 000000000..d1f3ec0f0
--- /dev/null
+++ b/tests/test_utils_jsonext.py
@@ -0,0 +1,72 @@
+import pytest
+import sys
+import os
+from pathlib import Path
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
+from slic.utils.jsonext import *
+
+@pytest.mark.parametrize(
+    "input_obj, expected",
+    [
+        # Numpy array case
+        (np.array([1, 2, 3]), [1, 2, 3]),
+
+        # Numpy scalar case
+        (np.int32(42), 42),
+
+        # Complex number case
+        (complex(1, -1), {"real": 1.0, "imag": -1.0}),
+
+        # Path object case
+        (Path("/tmp/file.txt"), "/tmp/file.txt"),
+
+        # Set case
+        ({3, 1, 2}, [1, 2, 3]),
+
+        # Dict case
+        ({"a": np.array([10, 20])}, {"a": [10, 20]}),
+
+        # Dict case
+        ({"c": complex(2, 3)}, {"c": {"real": 2.0, "imag": 3.0}}),
+
+        # Mixte
+        (
+            {
+                "nested": {
+                    "arr": np.array([[10, 20], [30, 40]]),
+                    "complex_num": complex(-1, 5),
+                    "files": [Path("/file1"), Path("/file2")],
+                    "set_values": {100, 200},
+                    "inner": {"num": np.int16(7)},
+                }
+            },
+            {
+                "nested": {
+                    "arr": [[10, 20], [30, 40]],
+                    "complex_num": {"real": -1.0, "imag": 5.0},
+                    "files": ["/file1", "/file2"],
+                    "set_values": [100, 200],  # sets become sorted lists
+                    "inner": {"num": 7},
+                }
+            }
+        ),
+    ]
+)
+
+def test_json_validate_save_load(tmp_path, input_obj, expected):
+    # Validate the object by serializing and deserializing it with ExtendedJSONEncoder
+    validated = json_validate(input_obj)
+    # Assert that the validated object matches the expected JSON-compatible structure
+    assert validated == expected
+
+    # Save the original input object to a JSON file + test json_save()
+    filepath = tmp_path / "test.json"
+    json_save(input_obj, filepath)
+    # Confirm the file was created
+    assert filepath.exists()
+
+    # Load the JSON file back into a Python object + test json_load()
+    loaded = json_load(filepath)
+
+    # Assert the loaded object matches the expected JSON-compatible structure
+    assert loaded == expected
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