Add feature flag API to Client

bugsnag/__init__.py

@@ -8,6 +8,7 @@
     Breadcrumbs,
     OnBreadcrumbCallback
 )
+from bugsnag.feature_flags import FeatureFlag
 from bugsnag.legacy import (configuration, configure, configure_request,
                             add_metadata_tab, clear_request_config, notify,
                             auto_notify, before_notify, start_session,
@@ -21,4 +22,4 @@
            'auto_notify_exc_info', 'Notification', 'logger',
            'BreadcrumbType', 'Breadcrumb', 'Breadcrumbs',
            'OnBreadcrumbCallback', 'leave_breadcrumb', 'add_on_breadcrumb',
-           'remove_on_breadcrumb')
+           'remove_on_breadcrumb', 'FeatureFlag')

bugsnag/client.py

@@ -14,13 +14,25 @@
 )
 from bugsnag.configuration import Configuration, RequestConfiguration
 from bugsnag.event import Event
+from bugsnag.feature_flags import FeatureFlag, FeatureFlagDelegate
 from bugsnag.handlers import BugsnagHandler
 from bugsnag.sessiontracker import SessionTracker
 from bugsnag.utils import to_rfc3339
 
 __all__ = ('Client',)
 
 
+try:
+    from contextvars import ContextVar
+    _feature_flag_delegate_context_var = ContextVar(
+        'bugsnag-client-feature-flag-delegate',
+        default=None
+    )  # type: ContextVar[Optional[FeatureFlagDelegate]]
+except ImportError:
+    from bugsnag.utils import ThreadContextVar
+    _feature_flag_delegate_context_var = ThreadContextVar('bugsnag-client-feature-flag-delegate', default=None)  # type: ignore  # noqa: E501
+
+
 class Client:
     """
     A Bugsnag monitoring and reporting client.
@@ -78,8 +90,13 @@ def notify(self, exception: BaseException, asynchronous=None, **options):
         >>> client.notify(Exception('Example'))  # doctest: +SKIP
         """
 
-        event = Event(exception, self.configuration,
-                      RequestConfiguration.get_instance(), **options)
+        event = Event(
+            exception,
+            self.configuration,
+            RequestConfiguration.get_instance(),
+            **options,
+            feature_flag_delegate=self._feature_flag_delegate
+        )
 
         self._leave_breadcrumb_for_event(event)
         self.deliver(event, asynchronous=asynchronous)
@@ -94,8 +111,13 @@ def notify_exc_info(self, exc_type, exc_value, traceback,
 
         exception = exc_value
         options['traceback'] = traceback
-        event = Event(exception, self.configuration,
-                      RequestConfiguration.get_instance(), **options)
+        event = Event(
+            exception,
+            self.configuration,
+            RequestConfiguration.get_instance(),
+            **options,
+            feature_flag_delegate=self._feature_flag_delegate
+        )
 
         self._leave_breadcrumb_for_event(event)
         self.deliver(event, asynchronous=asynchronous)
@@ -213,6 +235,39 @@ def log_handler(
     ) -> BugsnagHandler:
         return BugsnagHandler(client=self, extra_fields=extra_fields)
 
+    @property
+    def _feature_flag_delegate(self) -> FeatureFlagDelegate:
+        try:
+            feature_flag_delegate = _feature_flag_delegate_context_var.get()
+        except LookupError:
+            feature_flag_delegate = None
+
+        if feature_flag_delegate is None:
+            feature_flag_delegate = FeatureFlagDelegate()
+            _feature_flag_delegate_context_var.set(feature_flag_delegate)
+
+        return feature_flag_delegate
+
+    @property
+    def feature_flags(self) -> List[FeatureFlag]:
+        return self._feature_flag_delegate.to_list()
+
+    def add_feature_flag(
+        self,
+        name: Union[str, bytes],
+        variant: Union[None, str, bytes] = None
+    ) -> None:
+        self._feature_flag_delegate.add(name, variant)
+
+    def add_feature_flags(self, feature_flags: List[FeatureFlag]) -> None:
+        self._feature_flag_delegate.merge(feature_flags)
+
+    def clear_feature_flag(self, name: Union[str, bytes]) -> None:
+        self._feature_flag_delegate.remove(name)
+
+    def clear_feature_flags(self) -> None:
+        self._feature_flag_delegate.clear()
+
     @property
     def breadcrumbs(self) -> List[Breadcrumb]:
         return self.configuration.breadcrumbs

bugsnag/event.py

@@ -66,7 +66,10 @@ def __init__(self, exception: BaseException, config, request_config,
         self._breadcrumbs = [
             deepcopy(breadcrumb) for breadcrumb in config.breadcrumbs
         ]
-        self._feature_flag_delegate = FeatureFlagDelegate()
+        self._feature_flag_delegate = options.pop(
+            'feature_flag_delegate',
+            FeatureFlagDelegate()
+        ).copy()
 
         def get_config(key):
             return options.pop(key, getattr(self.config, key))

tests/test_client.py

@@ -12,7 +12,8 @@
     Client,
     Configuration,
     BreadcrumbType,
-    Breadcrumb
+    Breadcrumb,
+    FeatureFlag
 )
 
 import bugsnag.legacy as legacy
@@ -35,6 +36,8 @@ def setUp(self):
                              asynchronous=False,
                              install_sys_hook=False)
 
+        self.client.clear_feature_flags()
+
     # Initialisation
 
     def test_init_no_configuration(self):
@@ -1512,6 +1515,112 @@ def test_deleting_skip_bugsnag_attr_allows_notify(self):
 
         assert self.sent_report_count == 1
 
+    def test_feature_flags_can_be_added_individually(self):
+        self.client.add_feature_flag('one')
+        self.client.add_feature_flag('two', 'a')
+        self.client.add_feature_flag('three', None)
+
+        assert self.client.feature_flags == [
+            FeatureFlag('one'),
+            FeatureFlag('two', 'a'),
+            FeatureFlag('three')
+        ]
+
+    def test_feature_flags_can_be_added_in_bulk(self):
+        self.client.add_feature_flags([
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ])
+
+        assert self.client.feature_flags == [
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ]
+
+    def test_feature_flags_can_be_removed_individually(self):
+        self.client.add_feature_flags([
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ])
+
+        self.client.clear_feature_flag('b')
+
+        assert self.client.feature_flags == [
+            FeatureFlag('a', '1'),
+            FeatureFlag('c', '3')
+        ]
+
+    def test_feature_flags_can_be_cleared(self):
+        self.client.add_feature_flags([
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ])
+
+        self.client.clear_feature_flags()
+
+        assert self.client.feature_flags == []
+
+    def test_feature_flags_are_included_in_payload(self):
+        self.client.add_feature_flags([
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ])
+
+        self.client.notify(Exception('abc'))
+
+        assert self.sent_report_count == 1
+
+        payload = self.server.received[0]['json_body']
+        feature_flags = payload['events'][0]['featureFlags']
+
+        assert feature_flags == [
+            {'name': 'a', 'variant': '1'},
+            {'name': 'b'},
+            {'name': 'c', 'variant': '3'}
+        ]
+
+    def test_mutating_client_feature_flags_does_not_affect_event(self):
+        self.client.add_feature_flags([
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3')
+        ])
+
+        def on_error(event):
+            # adding a flag to the event directly should affect the payload
+            event.add_feature_flag('d')
+
+            # adding a flag to the client should not affect the payload as the
+            # event has already been created
+            self.client.add_feature_flag('e')
+
+        self.client.configuration.middleware.before_notify(on_error)
+        self.client.notify(Exception('abc'))
+
+        assert self.sent_report_count == 1
+
+        payload = self.server.received[0]['json_body']
+        feature_flags = payload['events'][0]['featureFlags']
+
+        assert feature_flags == [
+            {'name': 'a', 'variant': '1'},
+            {'name': 'b'},
+            {'name': 'c', 'variant': '3'},
+            {'name': 'd'}
+        ]
+
+        assert self.client.feature_flags == [
+            FeatureFlag('a', '1'),
+            FeatureFlag('b'),
+            FeatureFlag('c', '3'),
+            FeatureFlag('e')
+        ]
+
 
 @pytest.mark.parametrize("metadata,type", [
     (1234, 'int'),