Record exception on context manager exit

This updates the tracer context manager to automatically record
exceptions as events on exit if an exception was raised within the
context manager's context.

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

@@ -796,6 +796,7 @@ def use_span(
                 context_api.detach(token)
 
         except Exception as error:  # pylint: disable=broad-except
+            span.record_exception(error)
             if (
                 isinstance(span, Span)
                 and span.status is None

opentelemetry-sdk/tests/trace/test_trace.py

@@ -799,6 +799,24 @@ def test_record_exception(self):
             exception_event.attributes["exception.stacktrace"],
         )
 
+    def test_record_exception_context_manager(self):
+        try:
+            with self.tracer.start_as_current_span("span") as span:
+                raise RuntimeError("example error")
+        except RuntimeError:
+            pass
+        finally:
+            self.assertEqual(len(span.events), 1)
+            event = span.events[0]
+            self.assertEqual("exception", event.name)
+            self.assertEqual("RuntimeError", event.attributes["exception.type"])
+            self.assertEqual("example error", event.attributes["exception.message"])
+
+            stacktrace = '''in test_record_exception_context_manager
+    raise RuntimeError("example error")
+RuntimeError: example error'''
+            self.assertIn(stacktrace, event.attributes["exception.stacktrace"])
+
 
 def span_event_start_fmt(span_processor_name, span_name):
     return span_processor_name + ":" + span_name + ":start"