feat: Add contract test for streaming connection close on client shutdown

sdktests/server_side_stream_all.go

@@ -1,18 +1,24 @@
 package sdktests
 
 import (
+	"time"
+
+	h "github.com/launchdarkly/sdk-test-harness/v2/framework/helpers"
 	"github.com/launchdarkly/sdk-test-harness/v2/framework/ldtest"
 	"github.com/launchdarkly/sdk-test-harness/v2/mockld"
 	"github.com/launchdarkly/sdk-test-harness/v2/servicedef"
 
 	m "github.com/launchdarkly/go-test-helpers/v2/matchers"
+
+	"github.com/stretchr/testify/require"
 )
 
 func doServerSideStreamTests(t *ldtest.T) {
 	t.Run("requests", doServerSideStreamRequestTests)
 	t.Run("updates", doServerSideStreamUpdateTests)
 	t.Run("retry behavior", doServerSideStreamRetryTests)
 	t.Run("validation", doServerSideStreamValidationTests)
+	t.Run("connection lifecycle", doServerSideStreamConnectionLifecycleTests)
 }
 
 func doServerSideStreamRequestTests(t *ldtest.T) {
@@ -37,3 +43,39 @@ func doServerSideStreamRequestTests(t *ldtest.T) {
 func doServerSideStreamUpdateTests(t *ldtest.T) {
 	NewCommonStreamingTests(t, "doServerSideStreamUpdateTests").Updates(t)
 }
+
+func doServerSideStreamConnectionLifecycleTests(t *ldtest.T) {
+	// This test verifies that when the SDK client is closed, it actively closes its streaming
+	// connection rather than leaving the underlying TCP socket lingering. Go's HTTP server cancels
+	// the incoming request's Context when the client closes the underlying TCP connection, so we
+	// detect closure by waiting for that Context to be cancelled.
+	//
+	// This uses a plain streaming configuration (no data system), which exercises the legacy (FDv1)
+	// streaming data source. It is intentionally not gated behind any FDv2 capability.
+	t.Run("SDK closes streaming connection when client is closed", func(t *ldtest.T) {
+		dataSource := NewSDKDataSource(t, nil, DataSourceOptionStreaming())
+
+		client := NewSDKClient(t, dataSource)
+
+		streamRequest := dataSource.Endpoint().RequireConnection(t, time.Second*5)
+
+		// Closing the client should force the SDK to close its streaming connection. This is
+		// idempotent with the automatic close that happens at end-of-test.
+		require.NoError(t, client.Close())
+
+		h.RequireEventually(
+			t,
+			func() bool {
+				select {
+				case <-streamRequest.Context.Done():
+					return true
+				default:
+					return false
+				}
+			},
+			time.Second*3,
+			time.Millisecond*20,
+			"SDK did not close the streaming connection after the client was closed",
+		)
+	})
+}