Mechanism should default to true unless set explicitly

sentry_sdk/utils.py

@@ -637,13 +637,14 @@ def single_exception_from_error_tuple(
     mechanism=None,  # type: Optional[Dict[str, Any]]
 ):
     # type: (...) -> Dict[str, Any]
+    mechanism = mechanism or {"type": "generic", "handled": True}
+
     if exc_value is not None:
         errno = get_errno(exc_value)
     else:
         errno = None
 
     if errno is not None:
-        mechanism = mechanism or {"type": "generic"}
         mechanism.setdefault("meta", {}).setdefault("errno", {}).setdefault(
             "number", errno
         )

tests/integrations/wsgi/test_wsgi.py

@@ -140,6 +140,10 @@ def dogpark(environ, start_response):
     assert error_event["transaction"] == "generic WSGI request"
     assert error_event["contexts"]["trace"]["op"] == "http.server"
     assert error_event["exception"]["values"][0]["type"] == "Exception"
+    assert error_event["exception"]["values"][0]["mechanism"] == {
+        "type": "wsgi",
+        "handled": False,
+    }
     assert (
         error_event["exception"]["values"][0]["value"]
         == "Fetch aborted. The ball was not returned."

tests/test_basics.py

@@ -91,6 +91,22 @@ def test_event_id(sentry_init, capture_events):
     assert Hub.current.last_event_id() == event_id
 
 
+def test_generic_mechanism(sentry_init, capture_events):
+    sentry_init()
+    events = capture_events()
+
+    try:
+        raise ValueError("aha!")
+    except Exception:
+        capture_exception()
+
+    (event,) = events
+    assert event["exception"]["values"][0]["mechanism"] == {
+        "type": "generic",
+        "handled": True,
+    }
+
+
 def test_option_before_send(sentry_init, capture_events):
     def before_send(event, hint):
         event["extra"] = {"before_send_called": True}