feat: run event handlers immediately, add STALE (0.7.0 compliance)

pkg/openfeature/event_executor.go

@@ -163,23 +163,35 @@ func (e *eventExecutor) removeClientHandler(name string, t EventType, c EventCal
 	e.scopedRegistry[name].callbacks[t] = entrySlice
 }
 
-// emitOnRegistration fulfils the spec requirement to fire ready events if associated provider is ready
-func (e *eventExecutor) emitOnRegistration(providerReference providerReference, t EventType, c EventCallback) {
-	if t != ProviderReady {
-		return
-	}
-
+// emitOnRegistration fulfils the spec requirement to fire events if the
+// event type and the state of the associated provider are compatible.
+func (e *eventExecutor) emitOnRegistration(
+	providerReference providerReference,
+	eventType EventType,
+	callback EventCallback,
+) {
 	s, ok := (providerReference.featureProvider).(StateHandler)
 	if !ok {
 		// not a state handler, hence ignore state emitting
 		return
 	}
 
-	if s.Status() == ReadyState {
-		(*c)(EventDetails{
-			providerName: (providerReference.featureProvider).Metadata().Name,
+	state := s.Status()
+
+	var message string
+	if state == ReadyState && eventType == ProviderReady {
+		message = "provider is in ready state"
+	} else if state == ErrorState && eventType == ProviderError {
+		message = "provider is in error state"
+	} else if state == StaleState && eventType == ProviderStale {
+		message = "provider is in stale state"
+	}
+
+	if message != "" {
+		(*callback)(EventDetails{
+			providerName: providerReference.featureProvider.Metadata().Name,
 			ProviderEventDetails: ProviderEventDetails{
-				Message: "provider is at ready state",
+				Message: message,
 			},
 		})
 	}

pkg/openfeature/event_executor_test.go

@@ -821,6 +821,208 @@ func TestEventHandler_ProviderReadiness(t *testing.T) {
 	})
 }
 
+// Requirement 5.3.3, Spec version 0.7.0: Handlers attached after the
+// provider is already in the associated state, MUST run immediately
+func TestEventHandler_HandlersRunImmediately(t *testing.T) {
+	t.Run("ready handler runs when provider ready", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: ReadyState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 1)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderReady, &callback)
+
+		select {
+		case <-rsp:
+			break
+		case <-time.After(200 * time.Millisecond):
+			t.Errorf("timed out waiting for callback")
+		}
+	})
+
+	t.Run("error handler runs when provider error", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: ErrorState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 1)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderError, &callback)
+
+		select {
+		case <-rsp:
+			break
+		case <-time.After(200 * time.Millisecond):
+			t.Errorf("timed out waiting for callback")
+		}
+	})
+
+	t.Run("stale handler runs when provider stale", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: StaleState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 1)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderStale, &callback)
+
+		select {
+		case <-rsp:
+			break
+		case <-time.After(200 * time.Millisecond):
+			t.Errorf("timed out waiting for callback")
+		}
+	})
+
+	t.Run("non-ready handler does not run when provider ready", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: ReadyState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 3)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderError, &callback)
+		AddHandler(ProviderStale, &callback)
+		AddHandler(ProviderConfigChange, &callback)
+
+		select {
+		case <-rsp:
+			t.Errorf("event must not emit for this handler")
+		case <-time.After(200 * time.Millisecond):
+			break
+		}
+	})
+
+	t.Run("non-error handler does not run when provider error", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: ErrorState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 3)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderReady, &callback)
+		AddHandler(ProviderStale, &callback)
+		AddHandler(ProviderConfigChange, &callback)
+
+		select {
+		case <-rsp:
+			t.Errorf("event must not emit for this handler")
+		case <-time.After(200 * time.Millisecond):
+			break
+		}
+	})
+
+	t.Run("non-stale handler does not run when provider stale", func(t *testing.T) {
+		defer t.Cleanup(initSingleton)
+
+		provider := struct {
+			FeatureProvider
+			StateHandler
+		}{
+			NoopProvider{},
+			&stateHandlerForTests{
+				State: StaleState,
+			},
+		}
+
+		if err := SetProvider(provider); err != nil {
+			t.Fatal(err)
+		}
+
+		rsp := make(chan EventDetails, 3)
+		callback := func(e EventDetails) {
+			rsp <- e
+		}
+
+		AddHandler(ProviderReady, &callback)
+		AddHandler(ProviderError, &callback)
+		AddHandler(ProviderConfigChange, &callback)
+
+		select {
+		case <-rsp:
+			t.Errorf("event must not emit for this handler")
+		case <-time.After(200 * time.Millisecond):
+			break
+		}
+	})
+}
+
 // non-spec bound validations
 
 func TestEventHandler_multiSubs(t *testing.T) {

pkg/openfeature/provider.go

@@ -26,6 +26,7 @@ const (
 	NotReadyState State = "NOT_READY"
 	ReadyState    State = "READY"
 	ErrorState    State = "ERROR"
+	StaleState    State = "STALE"
 
 	ProviderReady        EventType = "PROVIDER_READY"
 	ProviderConfigChange EventType = "PROVIDER_CONFIGURATION_CHANGED"