Fix JSON serialization of DeletionMark objects in Change.to_dict()

The Change.to_dict() method was returning raw DeletionMark objects instead
of calling their to_dict() method, causing 'TypeError: Object of type
DeletionMark is not JSON serializable' when serializing changes.

This fix ensures DeletionMark objects are properly converted to dictionaries
before serialization, consistent with how other nested objects like Region
and StylesInfo are handled.

Changes:
- Fix Change.to_dict() to call self.__deletionMark.to_dict() when present
- Handle None and missing deletionMark cases properly
- Add comprehensive test suite covering all serialization scenarios

Fixes: JSON serialization errors when changes contain deletion marks

Author: pablospe

draftable/endpoints/comparisons/changes.py

@@ -325,7 +325,9 @@ def to_dict(self):
             "stylesInfo": (
                 self.__stylesInfo.to_dict() if self.__stylesInfo else None
             ),
-            "deletionMark": self.__deletionMark,
+            "deletionMark": (
+                self.__deletionMark.to_dict() if self.__deletionMark else None
+            ),
         }
 
     def __repr__(self):

draftable/endpoints/comparisons/test_changes.py

@@ -0,0 +1,169 @@
+import json
+from .changes import Change, DeletionMark, ChangeDetails
+
+
+class TestDeletionMarkSerialization:
+    """Test that DeletionMark objects are properly serialized in Change.to_dict()"""
+
+    def test_deletion_mark_serialization(self):
+        """Test that DeletionMark objects are properly serialized in Change.to_dict()"""
+
+        # Create test data with a DeletionMark
+        change_data = {
+            "kind": "deletion",
+            "leftText": "Some deleted text",
+            "rightText": None,
+            "leftRegion": None,
+            "rightRegion": None,
+            "stylesInfo": None,
+            "deletionMark": {"pageIndex": 1, "point": [100, 200]},
+        }
+
+        # Create Change object
+        change = Change(change_data)
+
+        # Convert to dict (this should not raise a TypeError)
+        result_dict = change.to_dict()
+
+        # Verify the result can be JSON serialized
+        json_str = json.dumps(result_dict)
+
+        # Verify the structure is correct
+        assert result_dict["deletionMark"]["pageIndex"] == 1
+        assert result_dict["deletionMark"]["point"] == [100, 200]
+
+        # Verify we can round-trip through JSON
+        parsed_back = json.loads(json_str)
+        assert parsed_back["deletionMark"]["pageIndex"] == 1
+        assert parsed_back["deletionMark"]["point"] == [100, 200]
+
+    def test_deletion_mark_none(self):
+        """Test that None deletionMark is handled correctly"""
+
+        change_data = {
+            "kind": "insertion",
+            "leftText": None,
+            "rightText": "Some new text",
+            "leftRegion": None,
+            "rightRegion": None,
+            "stylesInfo": None,
+            "deletionMark": None,
+        }
+
+        change = Change(change_data)
+        result_dict = change.to_dict()
+
+        # Should be serializable and deletionMark should be None
+        json.dumps(result_dict)
+        assert result_dict["deletionMark"] is None
+
+    def test_deletion_mark_missing(self):
+        """Test that missing deletionMark is handled correctly"""
+
+        change_data = {
+            "kind": "modification",
+            "leftText": "Old text",
+            "rightText": "New text",
+            "leftRegion": None,
+            "rightRegion": None,
+            "stylesInfo": None,
+            # deletionMark is missing entirely
+        }
+
+        change = Change(change_data)
+        result_dict = change.to_dict()
+
+        # Should be serializable and deletionMark should be None
+        json.dumps(result_dict)
+        assert result_dict["deletionMark"] is None
+
+    def test_change_details_with_deletion_marks(self):
+        """Test that Changes with DeletionMarks can be serialized"""
+
+        change_details_data = {
+            "changes": [
+                {
+                    "kind": "deletion",
+                    "leftText": "Deleted text",
+                    "rightText": None,
+                    "deletionMark": {"pageIndex": 0, "point": [50, 100]},
+                },
+                {
+                    "kind": "insertion",
+                    "leftText": None,
+                    "rightText": "Added text",
+                    "deletionMark": None,
+                },
+            ],
+            "summary": {"anyChanges": True},
+        }
+
+        # Create ChangeDetails object
+        change_details = ChangeDetails(change_details_data)
+
+        # Convert to dict (this should not raise a TypeError)
+        result_dict = change_details.to_dict()
+
+        # Verify the result can be JSON serialized
+        json.dumps(result_dict)
+
+        # Verify structure is correct
+        assert len(result_dict["changes"]) == 2
+        assert result_dict["changes"][0]["deletionMark"]["pageIndex"] == 0
+        assert result_dict["changes"][0]["deletionMark"]["point"] == [50, 100]
+        assert result_dict["changes"][1]["deletionMark"] is None
+
+    def test_deletion_mark_direct_serialization(self):
+        """Test that DeletionMark objects can be directly serialized"""
+
+        deletion_mark_data = {"pageIndex": 2, "point": [150, 250]}
+
+        deletion_mark = DeletionMark(deletion_mark_data)
+
+        # Test to_dict method
+        result_dict = deletion_mark.to_dict()
+        assert result_dict["pageIndex"] == 2
+        assert result_dict["point"] == [150, 250]
+
+        # Test JSON serialization
+        json_str = json.dumps(result_dict)
+        parsed_back = json.loads(json_str)
+        assert parsed_back["pageIndex"] == 2
+        assert parsed_back["point"] == [150, 250]
+
+    def test_change_with_complex_nested_data(self):
+        """Test serialization of Change with multiple nested objects including DeletionMark"""
+
+        change_data = {
+            "kind": "replacement",
+            "leftText": "Old text",
+            "rightText": "New text",
+            "leftRegion": {
+                "pageIndex": 0,
+                "rectangles": [{"left": 10, "top": 20, "right": 100, "bottom": 50}],
+            },
+            "rightRegion": {
+                "pageIndex": 0,
+                "rectangles": [{"left": 10, "top": 20, "right": 120, "bottom": 50}],
+            },
+            "stylesInfo": {
+                "leftStyles": [{"color": "red", "font": "Arial", "size": 12}],
+                "rightStyles": [{"color": "blue", "font": "Arial", "size": 12}],
+                "leftStyleMap": "style1",
+                "rightStyleMap": "style2",
+            },
+            "deletionMark": {"pageIndex": 0, "point": [75, 35]},
+        }
+
+        change = Change(change_data)
+        result_dict = change.to_dict()
+
+        # Should be fully serializable
+        json.dumps(result_dict)
+
+        # Verify all nested structures are properly serialized
+        assert result_dict["deletionMark"]["pageIndex"] == 0
+        assert result_dict["deletionMark"]["point"] == [75, 35]
+        assert result_dict["leftRegion"]["pageIndex"] == 0
+        assert len(result_dict["leftRegion"]["rectangles"]) == 1
+        assert result_dict["stylesInfo"]["leftStyleMap"] == "style1"