itest: add wallet_synced field integration test

In this commit, we add an integration test that verifies the
wallet_synced field in GetInfoResponse correctly reflects the wallet's
sync state.

The test creates a node, verifies wallet_synced becomes true after
initial sync, then stops the node and mines blocks while it's offline.
After restart, the test polls GetInfo to observe the wallet catching up,
ideally capturing the transition from wallet_synced=false to true.

The test is registered in the "wallet sync" test case group.

itest/list_on_test.go

@@ -842,6 +842,9 @@ func init() {
 	allTestCases = appendPrefixed(
 		"wallet", allTestCases, walletTestCases,
 	)
+	allTestCases = appendPrefixed(
+		"wallet sync", allTestCases, walletSyncTestCases,
+	)
 	allTestCases = appendPrefixed(
 		"coop close with external delivery", allTestCases,
 		coopCloseWithExternalTestCases,

itest/lnd_wallet_sync_test.go

@@ -0,0 +1,71 @@
+package itest
+
+import (
+	"time"
+
+	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/stretchr/testify/require"
+)
+
+// walletSyncTestCases defines a set of tests for the wallet_synced field
+// in GetInfoResponse.
+var walletSyncTestCases = []*lntest.TestCase{
+	{
+		Name:     "wallet synced",
+		TestFunc: runTestWalletSynced,
+	},
+}
+
+// runTestWalletSynced tests that the wallet_synced field in GetInfoResponse
+// correctly reflects the wallet's sync state. It verifies that wallet_synced
+// is false while the wallet is catching up to new blocks, and becomes true
+// once fully synced.
+func runTestWalletSynced(ht *lntest.HarnessTest) {
+	// Create a test node.
+	alice := ht.NewNodeWithCoins("Alice", nil)
+
+	// Verify wallet starts synced.
+	resp := alice.RPC.GetInfo()
+	require.True(ht, resp.WalletSynced)
+	ht.Logf("Alice wallet_synced=%v", resp.WalletSynced)
+
+	// Stop Alice to create a clear sync gap while we mine blocks.
+	require.NoError(ht, alice.Stop(), "failed to stop Alice")
+
+	// Mine blocks while Alice is offline.
+	const numBlocks = 40
+	ht.Miner().MineBlocks(numBlocks)
+	_, minerHeight := ht.Miner().GetBestBlock()
+
+	// Restart Alice without waiting for full chain sync.
+	require.NoError(
+		ht, alice.Start(ht.Context()), "failed to restart Alice",
+	)
+
+	// While Alice is behind the miner height, wallet_synced must be false.
+	deadline := time.Now().Add(lntest.DefaultTimeout)
+	for {
+		resp := alice.RPC.GetInfo()
+		if int32(resp.BlockHeight) >= minerHeight {
+			break
+		}
+
+		require.Falsef(ht, resp.WalletSynced,
+			"wallet_synced=true while behind "+
+				"(nodeHeight=%v, minerHeight=%v)",
+			resp.BlockHeight, minerHeight)
+
+		if time.Now().After(deadline) {
+			require.Fail(ht, "timed out waiting for "+
+				"node to catch up")
+		}
+
+		time.Sleep(50 * time.Millisecond)
+	}
+
+	// Final verification that wallet_synced is true.
+	require.Eventually(ht, func() bool {
+		return alice.RPC.GetInfo().WalletSynced
+	}, lntest.DefaultTimeout, 200*time.Millisecond,
+		"wallet should be synced after waiting")
+}