fix: skip exposure event when in-experiment flag has no variant

flagsmith/flagsmith.py

@@ -369,7 +369,8 @@ def get_experiment_flag(
 
         The exposure event's ``value`` is the flag's variant key. It is only
         sent when the flag exists, is enabled and the identity is enrolled in
-        the feature's experiment (``flag.experiment.in_experiment``); any
+        the feature's experiment (``flag.experiment.in_experiment``) with a
+        variant; any
         other outcome is logged and skipped to keep experimentation data
         clean. A `DefaultFlag` served via the `default_flag_handler` counts
         as the feature not existing.
@@ -395,6 +396,12 @@ def get_experiment_flag(
                 FLAG_EXPOSURE_EVENT,
                 feature_name,
             )
+        elif flag.variant is None:
+            logger.debug(
+                "Not sending %s for feature %s: flag has no variant.",
+                FLAG_EXPOSURE_EVENT,
+                feature_name,
+            )
         else:
             self.track_exposure_event(
                 feature_name=feature_name,

tests/test_flagsmith.py

@@ -1268,6 +1268,46 @@ def test_get_experiment_flag__not_in_experiment__skips_exposure(
     )
 
 
+def test_get_experiment_flag__in_experiment_without_variant__skips_exposure(
+    mocker: MockerFixture, api_key: str, caplog: pytest.LogCaptureFixture
+) -> None:
+    # Given
+    config = EventProcessorConfig(events_api_url="http://test/")
+    flagsmith = Flagsmith(
+        environment_key=api_key, enable_events=True, event_processor_config=config
+    )
+    flag = Flag(
+        enabled=True,
+        value="blue",
+        feature_name="checkout_v2",
+        feature_id=1,
+        variant=None,
+        experiment=ExperimentMetadata(
+            id=42, name="New checkout CTA", in_experiment=True
+        ),
+    )
+    mocker.patch.object(
+        flagsmith,
+        "get_identity_flags",
+        return_value=Flags(flags={"checkout_v2": flag}),
+    )
+    mock_track = mocker.patch.object(flagsmith._event_processor, "track_exposure_event")
+
+    # When
+    with caplog.at_level(logging.DEBUG, logger="flagsmith.flagsmith"):
+        result = flagsmith.get_experiment_flag(
+            feature_name="checkout_v2", identifier="user1"
+        )
+
+    # Then
+    assert result is flag
+    mock_track.assert_not_called()
+    assert (
+        "Not sending $flag_exposure for feature checkout_v2: flag has no variant."
+        in caplog.messages
+    )
+
+
 @responses.activate()
 def test_flagsmith_posts_analytics_to_analytics_url_when_set(
     api_key: str, flags_json: str, mocker: MockerFixture