feat: validate_schema for literal error

raillabel_providerkit/validation/validate_schema/validate_schema.py

@@ -26,6 +26,8 @@ def _make_errors_readable(errors: ValidationError) -> list[str]:
             readable_errors.append(_convert_missing_error_to_string(error))
         elif error["type"] == "extra_forbidden":
             readable_errors.append(_convert_unexpected_field_error_to_string(error))
+        elif error["type"] == "literal_error":
+            readable_errors.append(_convert_literal_error_to_string(error))
         else:
             raise ValueError
 
@@ -40,6 +42,13 @@ def _convert_unexpected_field_error_to_string(error: dict) -> str:
     return f"{_build_error_path(error["loc"][:-1])}: found unexpected field '{error["loc"][-1]}'."
 
 
+def _convert_literal_error_to_string(error: dict) -> str:
+    return (
+        f"{_build_error_path(error["loc"])}: value '{error["input"]}' does not match allowed values "
+        f"({error["ctx"]["expected"]})."
+    )
+
+
 def _build_error_path(loc: list[str]) -> str:
     path = "$"
     for part in loc:

tests/test_raillabel_providerkit/validation/validate_schema/test_validate_schema.py

@@ -14,13 +14,13 @@ def test_no_errors__empty():
 
 
 def test_required_field_missing():
-    data = {"openlabel": {}}
+    data = {"openlabel": {"metadata": {}}}
 
     actual = validate_schema(data)
     assert len(actual) == 1
-    assert "$.openlabel" in actual[0]
+    assert "$.openlabel.metadata" in actual[0]
     assert "required" in actual[0]
-    assert "metadata" in actual[0]
+    assert "schema_version" in actual[0]
     assert "missing" in actual[0]
 
 
@@ -34,5 +34,16 @@ def test_unsupported_field():
     assert "UNSUPPORTED_FIELD" in actual[0]
 
 
+def test_unexpected_value():
+    data = {"openlabel": {"metadata": {"schema_version": "SOMETHING UNSUPPORTED"}}}
+
+    actual = validate_schema(data)
+    assert len(actual) == 1
+    assert "$.openlabel.metadata.schema_version" in actual[0]
+    assert "value" in actual[0]
+    assert "SOMETHING UNSUPPORTED" in actual[0]
+    assert "'1.0.0'" in actual[0]
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])