remove createContext...yet

Signed-off-by: tison <wander4096@gmail.com>

expression/main_test.go

@@ -16,14 +16,11 @@ package expression
 
 import (
 	"testing"
-	"time"
 
 	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/testkit/testmain"
-	"github.com/pingcap/tidb/util/mock"
 	"github.com/pingcap/tidb/util/testbridge"
 	"github.com/pingcap/tidb/util/timeutil"
-	"github.com/stretchr/testify/require"
 	"github.com/tikv/client-go/v2/tikv"
 	"go.uber.org/goleak"
 )
@@ -51,13 +48,3 @@ func TestMain(m *testing.M) {
 
 	goleak.VerifyTestMain(m, opts...)
 }
-
-func createContext(t *testing.T) *mock.Context {
-	ctx := mock.NewContext()
-	ctx.GetSessionVars().StmtCtx.TimeZone = time.Local
-	sc := ctx.GetSessionVars().StmtCtx
-	sc.TruncateAsWarning = true
-	require.NoError(t, ctx.GetSessionVars().SetSystemVar("max_allowed_packet", "67108864"))
-	ctx.GetSessionVars().PlanColumnID = 0
-	return ctx
-}