fix CI and go mod tidy

go.mod

@@ -59,7 +59,6 @@ require (
 	github.com/shirou/gopsutil v3.21.2+incompatible
 	github.com/sirupsen/logrus v1.6.0
 	github.com/soheilhy/cmux v0.1.4
-	github.com/stretchr/testify v1.6.1
 	github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2
 	github.com/tikv/pd v1.1.0-beta.0.20210323121136-78679e5e209d
 	github.com/twmb/murmur3 v1.1.3

go.sum

@@ -440,7 +440,6 @@ github.com/pingcap/kvproto v0.0.0-20210308063835-39b884695fb8 h1:t72qxPxunoKykkA
 github.com/pingcap/kvproto v0.0.0-20210308063835-39b884695fb8/go.mod h1:IOdRDPLyda8GX2hE/jO7gqaCV/PNFh8BZQCQZXfIOqI=
 github.com/pingcap/log v0.0.0-20191012051959-b742a5d432e9/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
 github.com/pingcap/log v0.0.0-20200511115504-543df19646ad/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
-github.com/pingcap/log v0.0.0-20201112100606-8f1e84a3abc8 h1:M+DNpOu/I3uDmwee6vcnoPd6GgSMqND4gxvDQ/W584U=
 github.com/pingcap/log v0.0.0-20201112100606-8f1e84a3abc8/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
 github.com/pingcap/log v0.0.0-20210317133921-96f4fcab92a4 h1:ERrF0fTuIOnwfGbt71Ji3DKbOEaP189tjym50u8gpC8=
 github.com/pingcap/log v0.0.0-20210317133921-96f4fcab92a4/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=

session/session_test.go

@@ -2889,7 +2889,7 @@ func (s *testSessionSuite2) TestUpdatePrivilege(c *C) {
 
 	_, err := tk1.Exec("update t2 set id = 666 where id = 1;")
 	c.Assert(err, NotNil)
-	c.Assert(strings.Contains(err.Error(), "privilege check fail"), IsTrue)
+	c.Assert(strings.Contains(err.Error(), "privilege check"), IsTrue)
 
 	// Cover a bug that t1 and t2 both require update privilege.
 	// In fact, the privlege check for t1 should be update, and for t2 should be select.