fix tests for 3.9

Author: dubloom

ddtrace/internal/core/events.py

@@ -26,7 +26,7 @@ def additional_handler(event_instance):
 
 This example shows how ``core.context_with_data()`` can be replaced by `core.context_with_event()`::
 
-    @span_context
+    @context_event
     class TestContextEvent(SpanContextEvent):
         # SpanContextEvent requires this attributes
         event_name = "test.event"
@@ -115,11 +115,14 @@ def context_event(cls: Any) -> Any:
         class MyEvent(SpanContextEvent):
             url: str  # Automatically gets event_field() applied
     """
-    annotations = getattr(cls, "__annotations__", {})
+
+    annotations = cls.__dict__.get("__annotations__", {})
 
     # For each annotated field without a default, set it to event_field()
     for name, _ in annotations.items():
-        if not hasattr(cls, name):
+        # Only apply `event_field()` for fields that don't define a default value
+        # in the class body.
+        if name not in cls.__dict__:
             setattr(cls, name, event_field())
 
     return dataclass(cls)

tests/internal/events/test_context_event.py

@@ -1,3 +1,4 @@
+import sys
 from types import TracebackType
 from typing import Optional
 from typing import Tuple
@@ -78,8 +79,12 @@ def _on_context_ended(
     assert len(_listeners[f"context.ended.{TestContextEvent.event_name}"].values()) == 1
 
 
+@pytest.mark.skipif(sys.version_info < (3, 10), reason="Requires Python 3.10+")
 def test_context_event_enforce_kwargs_error():
-    """Test that missing required fields raise TypeError."""
+    """Test that missing required fields raise TypeError.
+    On Python 3.9, we create a default value to every attributes because kw_only
+    is not available in dataclass field. Therefore we skip the test
+    """
     called = []
 
     @context_event