expression: fix test cases in TestWrapWithCastAsTime and TestCompareB…

…uiltin (pingcap#6024)

Those test cases use wrong timezone, they will fail when TimeZone set to Tokyo
and time.Now() is 01:04

expression/builtin_cast_test.go

@@ -1151,7 +1151,13 @@ func (s *testEvaluatorSuite) TestWrapWithCastAsTypesClasses(c *C) {
 }
 
 func (s *testEvaluatorSuite) TestWrapWithCastAsTime(c *C) {
-	defer testleak.AfterTest(c)()
+	sc := s.ctx.GetSessionVars().StmtCtx
+	save := sc.TimeZone
+	sc.TimeZone = time.UTC
+	defer func() {
+		testleak.AfterTest(c)()
+		sc.TimeZone = save
+	}()
 	cases := []struct {
 		expr Expression
 		tp   *types.FieldType
@@ -1188,13 +1194,13 @@ func (s *testEvaluatorSuite) TestWrapWithCastAsTime(c *C) {
 			tm,
 		},
 	}
-	for _, t := range cases {
+	for d, t := range cases {
 		expr := WrapWithCastAsTime(s.ctx, t.expr, t.tp)
 		res, isNull, err := expr.EvalTime(s.ctx, nil)
 		c.Assert(err, IsNil)
 		c.Assert(isNull, Equals, false)
 		c.Assert(res.Type, Equals, t.tp.Tp)
-		c.Assert(res.Compare(t.res), Equals, 0)
+		c.Assert(res.Compare(t.res), Equals, 0, Commentf("case %d res = %s, expect = %s", d, res, t.res))
 	}
 }
 

expression/integration_test.go

@@ -2603,7 +2603,7 @@ func (s *testIntegrationSuite) TestCompareBuiltin(c *C) {
 	tk.MustExec(`insert into t2 values(1, 1.1, "2017-08-01 12:01:01", "12:01:01", "abcdef", 0b10101)`)
 
 	result = tk.MustQuery("select coalesce(NULL, a), coalesce(NULL, b, a), coalesce(c, NULL, a, b), coalesce(d, NULL), coalesce(d, c), coalesce(NULL, NULL, e, 1), coalesce(f), coalesce(1, a, b, c, d, e, f) from t2")
-	result.Check(testkit.Rows(fmt.Sprintf("1 1.1 2017-08-01 12:01:01 12:01:01 %s 12:01:01 abcdef 21 1", time.Now().In(time.UTC).Format("2006-01-02"))))
+	result.Check(testkit.Rows(fmt.Sprintf("1 1.1 2017-08-01 12:01:01 12:01:01 %s 12:01:01 abcdef 21 1", time.Now().In(tk.Se.GetSessionVars().GetTimeZone()).Format("2006-01-02"))))
 
 	// nullif
 	result = tk.MustQuery(`SELECT NULLIF(NULL, 1), NULLIF(1, NULL), NULLIF(1, 1), NULLIF(NULL, NULL);`)