itest: cover postgres network separation

Author: ziggie1984

itest/list_on_test.go

@@ -787,6 +787,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "estimate on chain fee auto selected inputs",
 		TestFunc: testEstimateOnChainFeeAutoSelectedInputs,
 	},
+	{
+		Name:     "postgres network separation",
+		TestFunc: testPostgresNetworkSeparation,
+	},
 }
 
 // appendPrefixed is used to add a prefix to each test name in the subtests

itest/lnd_postgres_network_separation_test.go

@@ -0,0 +1,67 @@
+package itest
+
+import (
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/lightningnetwork/lnd/sqldb"
+	"github.com/stretchr/testify/require"
+)
+
+const networkMismatchErr = "database network mismatch"
+
+// testPostgresNetworkSeparation verifies that lnd refuses to start when the
+// active Bitcoin network does not match the network stored in the postgres
+// metadata table. This prevents silent data corruption that would occur if a
+// user accidentally reused the same postgres DSN across different networks.
+//
+// The test flow is:
+//  1. Start lnd on regtest with native SQL enabled → first startup writes
+//     "regtest" into the metadata table.
+//  2. Stop the node.
+//  3. Restart lnd with the same postgres DSN but switch to simnet → lnd must
+//     detect the network mismatch and exit with an error.
+func testPostgresNetworkSeparation(ht *lntest.HarnessTest) {
+	// This test is only relevant for the postgres backend with native SQL.
+	if !ht.IsPostgresBackend() {
+		ht.Skip("node not running with postgres backend")
+	}
+
+	alice := ht.NewNodeWithCoins("Alice", []string{"--db.use-native-sql"})
+
+	// Confirm the node started successfully on the initial network.
+	require.NoError(ht, alice.Stop())
+
+	// Assert the mismatch condition directly at the store layer so this
+	// test can't pass due to an unrelated startup failure.
+	store, err := sqldb.NewPostgresStore(&sqldb.PostgresConfig{
+		Dsn:     alice.Cfg.PostgresDsn,
+		Timeout: defaultTimeout,
+	})
+	require.NoError(ht, err)
+	defer store.Close()
+
+	err = store.ValidateNetwork(ht.Context(), chaincfg.SimNetParams.Name)
+	require.ErrorContains(ht, err, networkMismatchErr)
+
+	// Now restart alice but override the network to simnet. The DSN still
+	// points at the same postgres database, so lnd should detect the
+	// mismatch and refuse to start.
+	//
+	// We append --bitcoin.simnet and remove --bitcoin.regtest by
+	// overriding via ExtraArgs (ExtraArgs are appended last and take
+	// precedence over the generated args).
+	alice.Cfg.NetParams = &chaincfg.SimNetParams
+	alice.SetExtraArgs([]string{
+		"--db.use-native-sql",
+		"--bitcoin.simnet",
+		"--bitcoin.node=neutrino",
+	})
+
+	// StartLndCmd launches the process without waiting for it to become
+	// ready, which is what we want since we expect it to exit early.
+	require.NoError(ht, alice.StartLndCmd(ht.Context()))
+
+	// The process should exit with a non-zero status due to the network
+	// mismatch error returned by ValidateNetwork.
+	require.ErrorContains(ht, alice.WaitForProcessExit(), "exit status 1")
+}

lntest/harness.go

@@ -1438,6 +1438,12 @@ func (h *HarnessTest) IsNeutrinoBackend() bool {
 	return h.manager.chainBackend.Name() == NeutrinoBackendName
 }
 
+// IsPostgresBackend returns true if the test harness is configured to use a
+// Postgres database backend.
+func (h *HarnessTest) IsPostgresBackend() bool {
+	return h.manager.dbBackend == node.BackendPostgres
+}
+
 // fundCoins attempts to send amt satoshis from the internal mining node to the
 // targeted lightning node. The confirmed boolean indicates whether the
 // transaction that pays to the target should confirm. For neutrino backend,