sqldb: add validate-network unit tests

diff --git a/chainparams/store_test.go b/chainparams/store_test.go
new file mode 100644
index 0000000..bc0f45b
--- /dev/null
+++ b/chainparams/store_test.go
@@ -0,0 +1,87 @@
+//go:build test_db_postgres || test_db_sqlite
+
+package chainparams
+
+import (
+	"testing"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/stretchr/testify/require"
+)
+
+// TestValidateNetworkMismatch verifies that ValidateNetwork persists the first
+// network and fails when a different network is used later.
+func TestValidateNetworkMismatch(t *testing.T) {
+	t.Parallel()
+
+	store := NewStore(newTestDB(t))
+
+	// First call: persists regtest into the store.
+	err := store.ValidateNetwork(t.Context(), &chaincfg.RegressionNetParams)
+	require.NoError(t, err)
+
+	// Second call: a different network — must fail with ErrNetworkMismatch.
+	err = store.ValidateNetwork(t.Context(), &chaincfg.SimNetParams)
+	require.ErrorIs(t, err, ErrNetworkMismatch)
+}
+
+// TestValidateNetworkSameNetwork verifies that ValidateNetwork succeeds when
+// called repeatedly with the same network (idempotent-match path).
+func TestValidateNetworkSameNetwork(t *testing.T) {
+	t.Parallel()
+
+	store := NewStore(newTestDB(t))
+
+	// First call: persists the network.
+	err := store.ValidateNetwork(t.Context(), &chaincfg.RegressionNetParams)
+	require.NoError(t, err)
+
+	// Second call: same network again — reads the stored value and must
+	// succeed (idempotent match).
+	err = store.ValidateNetwork(t.Context(), &chaincfg.RegressionNetParams)
+	require.NoError(t, err)
+}
+
+// TestValidateNetworkNormalizesTestnet verifies that network aliases collapse
+// to the same persisted value.
+func TestValidateNetworkNormalizesTestnet(t *testing.T) {
+	t.Parallel()
+
+	store := NewStore(newTestDB(t))
+
+	// First call: persists canonical testnet3 parameters.
+	err := store.ValidateNetwork(t.Context(), &chaincfg.TestNet3Params)
+	require.NoError(t, err)
+
+	// Second call: same logical network, different Name field — still
+	// matches after normalization (not ErrNetworkMismatch).
+	testnetAlias := chaincfg.TestNet3Params
+	testnetAlias.Name = "testnet"
+
+	err = store.ValidateNetwork(t.Context(), &testnetAlias)
+	require.NoError(t, err)
+}
+
+// TestValidateNetworkRejectsEmptyName verifies that malformed network params
+// are rejected before touching the database.
+func TestValidateNetworkRejectsEmptyName(t *testing.T) {
+	t.Parallel()
+
+	store := NewStore(newTestDB(t))
+
+	// Empty Params.Name — rejected before any database read or write.
+	err := store.ValidateNetwork(t.Context(), &chaincfg.Params{})
+	require.ErrorContains(t, err, "must define a network")
+}
+
+// TestValidateNetworkRejectsNilParams verifies that callers provide network
+// parameters.
+func TestValidateNetworkRejectsNilParams(t *testing.T) {
+	t.Parallel()
+
+	store := NewStore(newTestDB(t))
+
+	// Nil params — rejected before any database read or write.
+	err := store.ValidateNetwork(t.Context(), nil)
+	require.ErrorContains(t, err, "must not be nil")
+}
diff --git a/chainparams/test_postgres.go b/chainparams/test_postgres.go
new file mode 100644
index 0000000..698f150
--- /dev/null
+++ b/chainparams/test_postgres.go
@@ -0,0 +1,21 @@
+//go:build test_db_postgres && !test_db_sqlite
+
+package chainparams
+
+import (
+	"testing"
+
+	"github.com/lightningnetwork/lnd/sqldb"
+)
+
+// newTestDB creates a Postgres-backed BaseDB for use in unit tests.
+func newTestDB(t testing.TB) *sqldb.BaseDB {
+	pgFixture := sqldb.NewTestPgFixture(
+		t, sqldb.DefaultPostgresFixtureLifetime,
+	)
+	t.Cleanup(func() {
+		pgFixture.TearDown(t)
+	})
+
+	return sqldb.NewTestPostgresDB(t, pgFixture).GetBaseDB()
+}
diff --git a/chainparams/test_sqlite.go b/chainparams/test_sqlite.go
new file mode 100644
index 0000000..998b57d
--- /dev/null
+++ b/chainparams/test_sqlite.go
@@ -0,0 +1,14 @@
+//go:build !test_db_postgres && test_db_sqlite
+
+package chainparams
+
+import (
+	"testing"
+
+	"github.com/lightningnetwork/lnd/sqldb"
+)
+
+// newTestDB creates a SQLite-backed BaseDB for use in unit tests.
+func newTestDB(t testing.TB) *sqldb.BaseDB {
+	return sqldb.NewTestSqliteDB(t).GetBaseDB()
+}