itest: add test for litd surviving lnd shutdown

Author: Vandit1604

itest/litd_lnd_shutdown_test.go

@@ -0,0 +1,129 @@
+package itest
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/lightninglabs/lightning-terminal/litrpc"
+	"github.com/lightninglabs/lightning-terminal/subservers"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lntest/wait"
+	"github.com/stretchr/testify/require"
+)
+
+// testLitdSurvivesLndShutdown asserts that when lnd stops in integrated mode,
+// litd keeps running and its status endpoint stays reachable, reporting lnd as
+// stopped rather than cascading to a full litd shutdown.
+func testLitdSurvivesLndShutdown(ctx context.Context, net *NetworkHarness,
+	t *harnessTest) {
+
+	// Use a dedicated, throwaway node so that stopping its lnd cannot
+	// affect any other test.
+	node, err := net.NewNode(
+		t.t, "lnd-stop", nil, false, true, "--autopilot.disable",
+	)
+	require.NoError(t.t, err)
+
+	// The harness ShutdownNode stops litd (via its StopDaemon) and waits
+	// for the process to exit, so no manual litd shutdown is needed here.
+	defer func() {
+		_ = net.ShutdownNode(node)
+	}()
+
+	ctxt, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+
+	rawConn, err := connectLitRPC(
+		ctxt, node.Cfg.LitAddr(), node.Cfg.LitTLSCertPath,
+		node.Cfg.LitMacPath,
+	)
+	require.NoError(t.t, err)
+	defer func() { _ = rawConn.Close() }()
+
+	statusClient := litrpc.NewStatusClient(rawConn)
+
+	// lnd should be running before we stop it.
+	resp, err := statusClient.SubServerStatus(
+		ctxt, &litrpc.SubServerStatusReq{},
+	)
+	require.NoError(t.t, err)
+
+	lndStatus, ok := resp.SubServers[subservers.LND]
+	require.True(t.t, ok, "expected lnd sub-server status")
+	require.True(t.t, lndStatus.Running, "lnd should be running initially")
+
+	// Stop lnd (but not litd) via the lnrpc StopDaemon. The call may return
+	// an error as the connection is torn down, which is expected.
+	_, _ = node.LightningClient.StopDaemon(ctxt, &lnrpc.StopRequest{})
+
+	// litd's status endpoint must remain reachable and must report lnd as
+	// no longer running, with an error explaining why. We poll because lnd
+	// shutdown is asynchronous.
+	err = wait.NoError(func() error {
+		ctxs, cancels := context.WithTimeout(
+			context.Background(), defaultTimeout,
+		)
+		defer cancels()
+
+		resp, err := statusClient.SubServerStatus(
+			ctxs, &litrpc.SubServerStatusReq{},
+		)
+		if err != nil {
+			return fmt.Errorf("litd status endpoint unreachable "+
+				"after lnd stopped: %w", err)
+		}
+
+		lndStatus, ok := resp.SubServers[subservers.LND]
+		if !ok {
+			return fmt.Errorf("no lnd sub-server status returned")
+		}
+
+		if lndStatus.Running {
+			return fmt.Errorf("lnd still reported as running")
+		}
+
+		if lndStatus.Error == "" {
+			return fmt.Errorf("lnd error message not yet set")
+		}
+
+		return nil
+	}, defaultTimeout)
+	require.NoError(t.t, err)
+
+	// litd's process itself must keep running after lnd has stopped: its
+	// status endpoint stays reachable. The LIT sub-server is reported as no
+	// longer running, since litd cannot function without lnd, but the
+	// endpoint continuing to answer at all is what proves litd did not
+	// cascade down with lnd. Check this holds over time.
+	err = wait.InvariantNoError(func() error {
+		ctxs, cancels := context.WithTimeout(
+			context.Background(), defaultTimeout,
+		)
+		defer cancels()
+
+		resp, err := statusClient.SubServerStatus(
+			ctxs, &litrpc.SubServerStatusReq{},
+		)
+		if err != nil {
+			return fmt.Errorf("litd status endpoint must stay "+
+				"reachable after lnd stopped: %w", err)
+		}
+
+		litStatus, ok := resp.SubServers[subservers.LIT]
+		if !ok {
+			return fmt.Errorf("no lit sub-server status returned")
+		}
+
+		if litStatus.Running {
+			return fmt.Errorf("lit sub-server should be reported " +
+				"as stopped once lnd has stopped")
+		}
+
+		if litStatus.Error == "" {
+			return fmt.Errorf("lit sub-server error message not set")
+		}
+
+		return nil
+	}, defaultTimeout)
+	require.NoError(t.t, err)
+}

itest/litd_test_list_on_test.go

@@ -31,4 +31,8 @@ var allTestCases = []*testCase{
 		name: "kvdb to sql migration",
 		test: testKvdbSQLMigration,
 	},
+	{
+		name: "litd survives lnd shutdown",
+		test: testLitdSurvivesLndShutdown,
+	},
 }