feat: Add basic state management tests for streaming connections

mockld/polling_service.go

@@ -158,39 +158,34 @@ func (p *PollingService) standardPollingHandler() http.Handler {
 			return nil
 		}
 
-		// QUESTION: How dynamic do we need to make this?
-		serverIntent := framework.ServerIntent{
-			Payloads: []framework.Payload{
-				{
-					ID:     "payloadID",
-					Target: 1,
-					Code:   "xfer-full",
-					Reason: "payload-missing",
-				},
-			},
-		}
-
-		payloadTransferred := framework.PayloadTransferred{
-			//nolint:godox
-			// TODO: Need to replace this with a valid state value
-			State:   "state",
-			Version: 1,
-		}
+		events := make([]framework.PayloadEvent, 0, len(fdv2SdkData.events)+2)
 
-		events := make([]framework.PayloadEvent, 0, len(fdv2SdkData)+2)
 		events = append(events, framework.PayloadEvent{
-			Name:      "server-intent",
-			EventData: serverIntent,
-		})
-		for _, obj := range fdv2SdkData {
+			Name: "server-intent",
+			EventData: framework.ServerIntent{
+				Payloads: []framework.Payload{
+					{
+						ID:     "payloadID",
+						Target: 1,
+						Code:   fdv2SdkData.intentCode,
+						Reason: fdv2SdkData.intentReason,
+					},
+				},
+			}})
+
+		for _, obj := range fdv2SdkData.events {
 			events = append(events, framework.PayloadEvent{
 				Name:      "put-object",
 				EventData: obj,
 			})
 		}
+
 		events = append(events, framework.PayloadEvent{
-			Name:      "payload-transferred",
-			EventData: payloadTransferred,
+			Name: "payload-transferred",
+			EventData: framework.PayloadTransferred{
+				State:   fdv2SdkData.state,
+				Version: 1,
+			},
 		})
 
 		payload := framework.PollingPayload{

mockld/sdk_data.go

@@ -43,7 +43,22 @@ type SDKData interface {
 	Serialize() []byte
 }
 
-type FDv2SDKData []framework.BaseObject
+type FDv2SDKData struct {
+	intentCode   string
+	intentReason string
+	state        string
+
+	events []framework.BaseObject
+}
+
+func NewFDv2SDKData(intentCode, intentReason, state string, events []framework.BaseObject) FDv2SDKData {
+	return FDv2SDKData{
+		intentCode:   intentCode,
+		intentReason: intentReason,
+		state:        state,
+		events:       events,
+	}
+}
 
 func (f FDv2SDKData) Serialize() []byte {
 	return jsonhelpers.ToJSON(f)
@@ -85,7 +100,12 @@ func (d ServerSDKData) ConvertToFDv2SDKData(t *ldtest.T) FDv2SDKData {
 		}
 	}
 
-	return payloadObjects
+	return FDv2SDKData{
+		intentCode:   "xfer-full",
+		intentReason: "initial",
+		state:        "initial",
+		events:       payloadObjects,
+	}
 }
 
 // ClientSDKData contains simulated LaunchDarkly environment data for a client-side SDK.
@@ -112,8 +132,7 @@ type ClientSDKFlagWithKey struct {
 }
 
 func EmptyServerSDKData() SDKData {
-	var data FDv2SDKData = make([]framework.BaseObject, 0)
-	return data
+	return NewFDv2SDKData("xfer-full", "payload-missing", "initial", make([]framework.BaseObject, 0))
 }
 
 func EmptyClientSDKData() SDKData {
@@ -194,14 +213,21 @@ func normalizeSegment(key string, data json.RawMessage) (json.RawMessage, error)
 }
 
 type ServerSDKDataBuilder struct {
-	flags    map[string]json.RawMessage
-	segments map[string]json.RawMessage
+	flags        map[string]json.RawMessage
+	segments     map[string]json.RawMessage
+	intentCode   string
+	intentReason string
+	state        string
 }
 
 func NewServerSDKDataBuilder() *ServerSDKDataBuilder {
 	return &ServerSDKDataBuilder{
 		flags:    make(map[string]json.RawMessage),
 		segments: make(map[string]json.RawMessage),
+
+		intentCode:   "xfer-full",
+		intentReason: "payload-missing",
+		state:        "initial",
 	}
 }
 
@@ -242,7 +268,27 @@ func (b *ServerSDKDataBuilder) Build() FDv2SDKData {
 		})
 	}
 
-	return events
+	return FDv2SDKData{
+		intentCode:   b.intentCode,
+		intentReason: b.intentReason,
+		state:        b.state,
+		events:       events,
+	}
+}
+
+func (b *ServerSDKDataBuilder) IntentCode(code string) *ServerSDKDataBuilder {
+	b.intentCode = code
+	return b
+}
+
+func (b *ServerSDKDataBuilder) IntentReason(reason string) *ServerSDKDataBuilder {
+	b.intentReason = reason
+	return b
+}
+
+func (b *ServerSDKDataBuilder) State(state string) *ServerSDKDataBuilder {
+	b.state = state
+	return b
 }
 
 func (b *ServerSDKDataBuilder) RawFlag(key string, data json.RawMessage) *ServerSDKDataBuilder {

mockld/streaming_service.go

@@ -125,37 +125,26 @@ func (s *StreamingService) makeXferFull() []eventsource.Event {
 
 	fdv2SdkData, ok := s.initialData.(FDv2SDKData)
 	if !ok {
-		s.debugLogger.Println("poller cannot handle non-fdv2 sdk data at this time")
+		s.debugLogger.Println("streamer cannot handle non-fdv2 sdk data at this time")
 		return nil
 	}
 
-	// QUESTION: How dynamic do we need to bother making this?
-	serverIntent := framework.ServerIntent{
-		Payloads: []framework.Payload{
-			{
-				ID:     "payloadID",
-				Target: 1,
-				Code:   "xfer-full",
-				Reason: "payload-missing",
-			},
-		},
-	}
-
-	// QUESTION: How dynamic do we need to bother making this?
-	payloadTransferred := framework.PayloadTransferred{
-		//nolint:godox
-		// TODO: Need to replace this with a valid state value
-		State:   "state",
-		Version: 1,
-	}
-
-	events := make([]eventsource.Event, 0, len(fdv2SdkData)+2)
+	events := make([]eventsource.Event, 0, len(fdv2SdkData.events)+2)
 	events = append(events, eventImpl{
 		name: "server-intent",
-		data: serverIntent,
+		data: framework.ServerIntent{
+			Payloads: []framework.Payload{
+				{
+					ID:     "payloadID",
+					Target: 1,
+					Code:   fdv2SdkData.intentCode,
+					Reason: fdv2SdkData.intentReason,
+				},
+			},
+		},
 	})
 
-	for _, obj := range fdv2SdkData {
+	for _, obj := range fdv2SdkData.events {
 		events = append(events, eventImpl{
 			name: "put-object",
 			data: obj,
@@ -164,7 +153,10 @@ func (s *StreamingService) makeXferFull() []eventsource.Event {
 
 	events = append(events, eventImpl{
 		name: "payload-transferred",
-		data: payloadTransferred,
+		data: framework.PayloadTransferred{
+			State:   fdv2SdkData.state,
+			Version: 1,
+		},
 	})
 
 	s.lock.RUnlock()

sdktests/common_tests_stream_fdv2.go

@@ -0,0 +1,175 @@
+package sdktests
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/launchdarkly/go-test-helpers/v2/httphelpers"
+	m "github.com/launchdarkly/go-test-helpers/v2/matchers"
+	"github.com/launchdarkly/sdk-test-harness/v2/framework/harness"
+	"github.com/launchdarkly/sdk-test-harness/v2/framework/ldtest"
+	"github.com/launchdarkly/sdk-test-harness/v2/mockld"
+
+	"github.com/launchdarkly/go-sdk-common/v3/ldcontext"
+	"github.com/launchdarkly/go-sdk-common/v3/ldvalue"
+
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	initialValue = ldvalue.String("initial value") //nolint:gochecknoglobals
+	updatedValue = ldvalue.String("updated value") //nolint:gochecknoglobals
+
+	newInitialValue = ldvalue.String("new initial value") //nolint:gochecknoglobals
+
+	defaultValue = ldvalue.String("default value") //nolint:gochecknoglobals
+)
+
+func (c CommonStreamingTests) FDv2(t *ldtest.T) {
+	t.Run("reconnection state management", c.StateTransitions)
+	t.Run(
+		"updates are not complete until payload transferred is sent",
+		c.UpdatesAreNotCompleteUntilPayloadTransferredIsSent)
+}
+
+func (c CommonStreamingTests) StateTransitions(t *ldtest.T) {
+	t.Run("initializes from an empty state", c.InitializeFromEmptyState)
+	t.Run("saves previously known state", c.SavesPreviouslyKnownState)
+	t.Run("replaces previously known state", c.ReplacesPreviouslyKnownState)
+	t.Run("updates previously known state", c.UpdatesPreviouslyKnownState)
+}
+
+func (c CommonStreamingTests) InitializeFromEmptyState(t *ldtest.T) {
+	streamEndpoint := makeSequentialStreamHandler(t, c.makeSDKDataWithFlag("flag-key", 1, initialValue))
+	t.Defer(streamEndpoint.Close)
+	client := NewSDKClient(t, WithStreamingConfig(baseStreamConfig(streamEndpoint)))
+
+	expectedEvaluations := map[string]ldvalue.Value{"flag-key": initialValue}
+	validatePayloadReceived(t, streamEndpoint, client, "", expectedEvaluations)
+}
+
+func (c CommonStreamingTests) SavesPreviouslyKnownState(t *ldtest.T) {
+	dataBefore := c.makeSDKDataWithFlag("flag-key", 1, initialValue)
+	dataAfter := mockld.NewServerSDKDataBuilder().IntentCode("xfer-none").IntentReason("up-to-date").Build()
+	streamEndpoint := makeSequentialStreamHandler(t, dataBefore, dataAfter)
+	t.Defer(streamEndpoint.Close)
+	client := NewSDKClient(t, WithStreamingConfig(baseStreamConfig(streamEndpoint)))
+
+	expectedEvaluations := map[string]ldvalue.Value{"flag-key": initialValue}
+	request := validatePayloadReceived(t, streamEndpoint, client, "", expectedEvaluations)
+	request.Cancel() // Drop the stream and allow the SDK to reconnect
+
+	validatePayloadReceived(t, streamEndpoint, client, "initial", expectedEvaluations)
+}
+
+func (c CommonStreamingTests) ReplacesPreviouslyKnownState(t *ldtest.T) {
+	dataBefore := c.makeSDKDataWithFlag("flag-key", 1, initialValue)
+	dataAfter := mockld.NewServerSDKDataBuilder().
+		IntentCode("xfer-full").
+		IntentReason("cant-catchup").
+		Flag(c.makeServerSideFlag("new-flag-key", 1, ldvalue.String("replacement value"))).
+		Build()
+	streamEndpoint := makeSequentialStreamHandler(t, dataBefore, dataAfter)
+	t.Defer(streamEndpoint.Close)
+	client := NewSDKClient(t, WithStreamingConfig(baseStreamConfig(streamEndpoint)))
+
+	expectedEvaluations := map[string]ldvalue.Value{"flag-key": initialValue, "new-flag-key": defaultValue}
+	request := validatePayloadReceived(t, streamEndpoint, client, "", expectedEvaluations)
+	request.Cancel() // Drop the stream and allow the SDK to reconnect
+
+	expectedEvaluations = map[string]ldvalue.Value{
+		"flag-key":     defaultValue,
+		"new-flag-key": ldvalue.String("replacement value")}
+	validatePayloadReceived(t, streamEndpoint, client, "initial", expectedEvaluations)
+}
+
+func (c CommonStreamingTests) UpdatesPreviouslyKnownState(t *ldtest.T) {
+	dataBefore := c.makeSDKDataWithFlag("flag-key", 1, initialValue)
+	dataAfter := mockld.NewServerSDKDataBuilder().
+		IntentCode("xfer-changes").
+		IntentReason("stale").
+		Flag(c.makeServerSideFlag("flag-key", 2, updatedValue)).
+		Flag(c.makeServerSideFlag("new-flag-key", 1, newInitialValue)).
+		Build()
+	streamEndpoint := makeSequentialStreamHandler(t, dataBefore, dataAfter)
+	t.Defer(streamEndpoint.Close)
+	client := NewSDKClient(t, WithStreamingConfig(baseStreamConfig(streamEndpoint)))
+
+	expectedEvaluations := map[string]ldvalue.Value{"flag-key": initialValue, "new-flag-key": defaultValue}
+	request := validatePayloadReceived(t, streamEndpoint, client, "", expectedEvaluations)
+	request.Cancel() // Drop the stream and allow the SDK to reconnect
+
+	expectedEvaluations = map[string]ldvalue.Value{"flag-key": updatedValue, "new-flag-key": newInitialValue}
+	validatePayloadReceived(t, streamEndpoint, client, "initial", expectedEvaluations)
+}
+
+func (c CommonStreamingTests) UpdatesAreNotCompleteUntilPayloadTransferredIsSent(t *ldtest.T) {
+	dataBefore := c.makeSDKDataWithFlag("flag-key", 1, initialValue)
+	stream := NewSDKDataSourceWithoutEndpoint(t, dataBefore)
+	streamEndpoint := requireContext(t).harness.NewMockEndpoint(stream.Handler(), t.DebugLogger(),
+		harness.MockEndpointDescription("streaming service"))
+	t.Defer(streamEndpoint.Close)
+	client := NewSDKClient(t, WithStreamingConfig(baseStreamConfig(streamEndpoint)))
+
+	_, err := streamEndpoint.AwaitConnection(time.Second)
+	require.NoError(t, err)
+
+	context := ldcontext.New("context-key")
+	flagKeyValue := basicEvaluateFlag(t, client, "flag-key", context, defaultValue)
+	m.In(t).Assert(flagKeyValue, m.JSONEqual(initialValue))
+
+	stream.streamingService.PushUpdate("flag", "flag-key", 2, c.makeFlagData("flag-key", 2, updatedValue))
+	stream.streamingService.PushUpdate("flag", "new-flag-key", 1, c.makeFlagData("new-flag-key", 1, newInitialValue))
+
+	require.Never(
+		t,
+		checkForUpdatedValue(t, client, "flag-key", context, initialValue, updatedValue, defaultValue),
+		time.Millisecond*100,
+		time.Millisecond*20,
+		"flag value was updated, but it should not have been",
+	)
+
+	require.Never(
+		t,
+		checkForUpdatedValue(t, client, "new-flag-key", context, defaultValue, newInitialValue, defaultValue),
+		time.Millisecond*100,
+		time.Millisecond*20,
+		"flag value was updated, but it should not have been",
+	)
+
+	stream.streamingService.PushPayloadTransferred("updated", 2)
+
+	pollUntilFlagValueUpdated(t, client, "flag-key", context, initialValue, updatedValue, defaultValue)
+	pollUntilFlagValueUpdated(t, client, "new-flag-key", context, defaultValue, newInitialValue, defaultValue)
+}
+
+func makeSequentialStreamHandler(t *ldtest.T, dataSources ...mockld.SDKData) *harness.MockEndpoint {
+	handlers := make([]http.Handler, len(dataSources))
+
+	for i, data := range dataSources {
+		stream := NewSDKDataSourceWithoutEndpoint(t, data)
+		handlers[i] = stream.Handler()
+	}
+
+	handler := httphelpers.SequentialHandler(handlers[0], handlers[1:]...)
+
+	return requireContext(t).harness.NewMockEndpoint(handler, t.DebugLogger(),
+		harness.MockEndpointDescription("streaming service"))
+}
+
+func validatePayloadReceived(t *ldtest.T,
+	streamEndpoint *harness.MockEndpoint, client *SDKClient,
+	state string, evaluations map[string]ldvalue.Value) harness.IncomingRequestInfo {
+	request, err := streamEndpoint.AwaitConnection(time.Second)
+	require.NoError(t, err)
+
+	m.In(t).Assert(request.URL.Query().Get("basis"), m.Equal(state))
+
+	context := ldcontext.New("context-key")
+	for flagKey, expectedValue := range evaluations {
+		actualValue := basicEvaluateFlag(t, client, flagKey, context, defaultValue)
+		m.In(t).Assert(actualValue, m.JSONEqual(expectedValue))
+	}
+
+	return request
+}