fix(CFT-223): Handle empty list to dict conversion for user_properties

src/configuration.py

@@ -1,6 +1,8 @@
 from dataclasses import dataclass, field
 from enum import Enum
 
+from keboola.component.exceptions import UserException
+
 
 # the encrypted keys (prefixed with # in Keboola) have to be prefixed with "encrypted_" here
 def encrypted_keys(key: str) -> str:
@@ -50,8 +52,15 @@ class GitConfiguration:
 @dataclass
 class Configuration:
     source: SourceEnum = SourceEnum.CODE
-    user_properties: dict[str, object] = field(default_factory=dict)
+    user_properties: dict[str, object] | list = field(default_factory=dict)
     venv: VenvEnum = VenvEnum.BASE
     packages: list[str] = field(default_factory=list)
     code: str = ""
     git: GitConfiguration = field(default_factory=GitConfiguration)
+
+    def __post_init__(self):
+        if isinstance(self.user_properties, list):
+            if len(self.user_properties) == 0:
+                self.user_properties = {}
+            else:
+                raise UserException("Invalid user_properties: non-empty list not supported")

tests/test_component.py

@@ -3,8 +3,10 @@
 
 import mock
 from freezegun import freeze_time
+from keboola.component.exceptions import UserException
 
 from component import Component
+from configuration import Configuration
 
 
 class TestComponent(unittest.TestCase):
@@ -19,6 +21,45 @@ def test_run_no_cfg_fails(self):
             comp.run()
 
 
+class TestConfigurationUserProperties(unittest.TestCase):
+    """Test cases for user_properties handling in Configuration dataclass.
+
+    These tests verify the fix for the 'eternal KBC bug' where the Keboola platform
+    converts empty JSON objects {} to empty arrays [] in configuration parameters.
+    """
+
+    def test_empty_list_converted_to_empty_dict(self):
+        """Empty list [] should be converted to empty dict {} via __post_init__."""
+        config = Configuration(user_properties=[])
+        self.assertEqual(config.user_properties, {})
+        self.assertIsInstance(config.user_properties, dict)
+
+    def test_non_empty_list_raises_user_exception(self):
+        """Non-empty list should raise UserException."""
+        with self.assertRaises(UserException) as context:
+            Configuration(user_properties=["item1", "item2"])
+        self.assertIn("non-empty list not supported", str(context.exception))
+
+    def test_dict_unchanged(self):
+        """Normal dict input should remain unchanged."""
+        test_dict = {"key1": "value1", "key2": 123}
+        config = Configuration(user_properties=test_dict)
+        self.assertEqual(config.user_properties, test_dict)
+        self.assertIsInstance(config.user_properties, dict)
+
+    def test_empty_dict_unchanged(self):
+        """Empty dict input should remain unchanged."""
+        config = Configuration(user_properties={})
+        self.assertEqual(config.user_properties, {})
+        self.assertIsInstance(config.user_properties, dict)
+
+    def test_default_user_properties_is_empty_dict(self):
+        """Default user_properties should be an empty dict."""
+        config = Configuration()
+        self.assertEqual(config.user_properties, {})
+        self.assertIsInstance(config.user_properties, dict)
+
+
 if __name__ == "__main__":
     # import sys;sys.argv = ['', 'Test.testName']
     unittest.main()