Add tests ensuring failed event serialization is handled correctly

[CT-2264](#7113) states
that failed serialization should result in an exception handling path
which will fire another event instead of raising an exception. This is
hard to test perfectly because the exception handling path for
serialization depending on whether pytest is present. If pytest isn't
present, a new event documentation the failed serialization is fired.
If pytest is present, the failed serialization gets raised as an exception.
Thus this added test ensures that the expected exception is raised and
assumes that the correct event will be fired normally.

tests/unit/test_events.py

@@ -1,3 +1,4 @@
+import pytest
 import re
 from typing import TypeVar
 
@@ -442,3 +443,21 @@ def test_date_serialization():
     ti_dict = ti.to_dict()
     assert ti_dict["started_at"].endswith("Z")
     assert ti_dict["completed_at"].endswith("Z")
+
+
+def test_bad_serialization():
+    """Tests that bad serialization enters the proper exception handling
+
+    When pytest is in use the exception handling of `BaseEvent` raises an
+    exception. When pytest isn't present, it fires a Note event. Thus to test
+    that bad serializations are properly handled, the best we can do is test
+    that the exception handling path is used.
+    """
+
+    with pytest.raises(Exception) as excinfo:
+        types.Note(param_event_doesnt_have="This should break")
+
+    assert (
+        str(excinfo.value)
+        == "[Note]: Unable to parse dict {'param_event_doesnt_have': 'This should break'}"
+    )