Improve code coverage for .Transaction()

internal_mocks.go

@@ -12,6 +12,20 @@ func (b mockTxBeginner) BeginTx(ctx context.Context) (Tx, error) {
 	return b.BeginTxFn(ctx)
 }
 
+// mockDBAdapter mocks the ksql.DBAdapter interface
+type mockDBAdapter struct {
+	ExecContextFn  func(ctx context.Context, query string, args ...interface{}) (Result, error)
+	QueryContextFn func(ctx context.Context, query string, args ...interface{}) (Rows, error)
+}
+
+func (m mockDBAdapter) ExecContext(ctx context.Context, query string, args ...interface{}) (Result, error) {
+	return m.ExecContextFn(ctx, query, args...)
+}
+
+func (m mockDBAdapter) QueryContext(ctx context.Context, query string, args ...interface{}) (Rows, error) {
+	return m.QueryContextFn(ctx, query, args...)
+}
+
 // mockTx mocks the ksql.Tx interface
 type mockTx struct {
 	DBAdapter

test_adapters.go

@@ -2370,6 +2370,26 @@ func TransactionTest(
 			})
 			tt.AssertErrContains(t, err, "KSQL", "fakeErrMsg")
 		})
+
+		t.Run("should report error if DBAdapter can't create transactions", func(t *testing.T) {
+			err := createTables(driver, connStr)
+			if err != nil {
+				t.Fatal("could not create test table!, reason:", err.Error())
+			}
+
+			db, closer := newDBAdapter(t)
+			defer closer.Close()
+
+			ctx := context.Background()
+			c := newTestDB(db, driver)
+
+			c.db = mockDBAdapter{}
+
+			err = c.Transaction(ctx, func(db Provider) error {
+				return nil
+			})
+			tt.AssertErrContains(t, err, "KSQL", "can't start transaction", "DBAdapter", "TxBeginner")
+		})
 	})
 }