clickhouse: honor DefaultMigrationsTableEngine when created WithInstance()

Before this patch, clickhouse.WithInstance() would not select
DefaultMigrationsTableEngine when no MigrationsTableEngine was provided
through the clickhouse.Config{} argument. This behaviour forces the
caller to always provide explicitely the config's MigrationsTableEngine.

This patch make it so DefaultMigrationsTableEngine is used when
MigrationsTableEngine is not provided through clickhouse.Config{}.

Signed-off-by: Alexandre Perrin <alex@kaworu.ch>

Author: Prometheus2677

database/clickhouse/clickhouse.go

@@ -127,6 +127,10 @@ func (ch *ClickHouse) init() error {
 		ch.config.MultiStatementMaxSize = DefaultMultiStatementMaxSize
 	}
 
+	if len(ch.config.MigrationsTableEngine) == 0 {
+		ch.config.MigrationsTableEngine = DefaultMigrationsTableEngine
+	}
+
 	return ch.ensureVersionTable()
 }
 

database/clickhouse/clickhouse_test.go

@@ -79,8 +79,8 @@ func TestCases(t *testing.T) {
 		t.Run("Migrate_"+engine, func(t *testing.T) { testMigrate(t, engine) })
 		t.Run("Version_"+engine, func(t *testing.T) { testVersion(t, engine) })
 		t.Run("Drop_"+engine, func(t *testing.T) { testDrop(t, engine) })
-
 	}
+	t.Run("WithInstanceDefaultConfigValues", func(t *testing.T) { testSimpleWithInstanceDefaultConfigValues(t) })
 }
 
 func testSimple(t *testing.T, engine string) {
@@ -106,6 +106,33 @@ func testSimple(t *testing.T, engine string) {
 	})
 }
 
+func testSimpleWithInstanceDefaultConfigValues(t *testing.T) {
+	dktesting.ParallelTest(t, specs, func(t *testing.T, c dktest.ContainerInfo) {
+		ip, port, err := c.Port(defaultPort)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		addr := clickhouseConnectionString(ip, port, "")
+		conn, err := sql.Open("clickhouse", addr)
+		if err != nil {
+			t.Fatal(err)
+		}
+		d, err := clickhouse.WithInstance(conn, &clickhouse.Config{})
+		if err != nil {
+			_ = conn.Close()
+			t.Fatal(err)
+		}
+		defer func() {
+			if err := d.Close(); err != nil {
+				t.Error(err)
+			}
+		}()
+
+		dt.Test(t, d, []byte("SELECT 1"))
+	})
+}
+
 func testMigrate(t *testing.T, engine string) {
 	dktesting.ParallelTest(t, specs, func(t *testing.T, c dktest.ContainerInfo) {
 		ip, port, err := c.Port(defaultPort)