fix: Handle empty error in JSON output

PR #1: #1
Co-authored-by: Timothée Mazzucotelli <[email protected]>

Author: rachmadaniHaryono

src/mkdocstrings/handlers/python/collector.py

@@ -152,8 +152,8 @@ def collect(self, identifier: str, config: dict) -> CollectorItem:
             error = "\n".join(("Error while loading JSON:", stdout, traceback.format_exc()))
             raise CollectionError(error) from exception
 
-        error = result.get("error")
-        if error:
+        if "error" in result:
+            error = result["error"]
             if "traceback" in result:
                 error += f"\n{result['traceback']}"
             raise CollectionError(error)

tests/test_collector.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+"""Tests for the `collector` module."""
+from unittest import mock
+
+import pytest
+
+from mkdocstrings.handlers.base import CollectionError
+from mkdocstrings.handlers.python import collector
+
+
+def test_init():
+    """Test init for collector.PythonCollector."""
+    assert collector.PythonCollector()
+
+
+@pytest.mark.parametrize(
+    ("retval", "exp_res"),
+    [
+        ({"error": "error1", "traceback": "hello"}, "error1\nhello"),
+        ({"error": "error1"}, "error1"),
+        ({"error": "", "traceback": "hello"}, "\nhello"),
+    ],
+)
+def test_collect_result_error(retval, exp_res):
+    """Test handling of errors when collecting an object.
+
+    Args:
+        retval: Return value to mock `json.loads` with.
+        exp_res: Expected result.
+    """
+    with mock.patch("mkdocstrings.handlers.python.collector.json.loads") as m_loads:
+        with pytest.raises(CollectionError) as excinfo:  # noqa: PT012
+            m_loads.return_value = retval
+            obj = collector.PythonCollector()
+            assert obj.collect("", {})
+            assert str(excinfo.value) == exp_res