diff --git a/ddl/ddl_db_test.go b/ddl/ddl_db_test.go
index 5021f444cf..525d667943 100644
--- a/ddl/ddl_db_test.go
+++ b/ddl/ddl_db_test.go
@@ -392,6 +392,7 @@ func sessionExec(c *C, s kv.Storage, sql string) {
 	se, err := tidb.CreateSession(s)
 	c.Assert(err, IsNil)
 	_, err = se.Execute("use test_db")
+	c.Assert(err, IsNil)
 	rs, err := se.Execute(sql)
 	c.Assert(err, IsNil, Commentf("err:%v", errors.ErrorStack(err)))
 	c.Assert(rs, IsNil)
@@ -672,6 +673,7 @@ func (s *testDBSuite) TestTruncateTable(c *C) {
 
 	is = sessionctx.GetDomain(ctx).InfoSchema()
 	newTblInfo, err := is.TableByName(model.NewCIStr("test"), model.NewCIStr("t"))
+	c.Assert(err, IsNil)
 	c.Assert(newTblInfo.Meta().ID, Greater, oldTblID)
 
 	// verify that the old table data has been deleted by background worker.
diff --git a/ddl/index_change_test.go b/ddl/index_change_test.go
index 1c40ec3c76..5985948df5 100644
--- a/ddl/index_change_test.go
+++ b/ddl/index_change_test.go
@@ -285,6 +285,9 @@ func (s *testIndexChangeSuite) checkAddPublic(d *ddl, ctx context.Context, write
 		return errors.Trace(err)
 	}
 	err = checkIndexExists(ctx, publicTbl, 6, 6, false)
+	if err != nil {
+		return errors.Trace(err)
+	}
 
 	var rows [][]types.Datum
 	publicTbl.IterRecords(ctx, publicTbl.FirstKey(), publicTbl.Cols(),
@@ -312,21 +315,29 @@ func (s *testIndexChangeSuite) checkDropWriteOnly(d *ddl, ctx context.Context, p
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, publicTbl, 8, 8, true)
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	// WriteOnlyTable update t set c2 = 7 where c1 = 8 and c2 = 8
 	err = writeTbl.UpdateRecord(ctx, 8, types.MakeDatums(8, 8), types.MakeDatums(8, 7), touchedMap(writeTbl))
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, publicTbl, 7, 8, true)
+	if err != nil {
+		return errors.Trace(err)
+	}
+
 	// WriteOnlyTable delete t where c1 = 8
 	err = writeTbl.RemoveRecord(ctx, 8, types.MakeDatums(8, 7))
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, publicTbl, 7, 8, false)
 	if err != nil {
 		return errors.Trace(err)
@@ -340,25 +351,34 @@ func (s *testIndexChangeSuite) checkDropDeleteOnly(d *ddl, ctx context.Context,
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, writeTbl, 9, 9, true)
+	if err != nil {
+		return errors.Trace(err)
+	}
+
 	// DeleteOnlyTable insert t values (10, 10)
 	_, err = delTbl.AddRecord(ctx, types.MakeDatums(10, 10))
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, writeTbl, 10, 10, false)
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	// DeleteOnlyTable update t set c2 = 10 where c1 = 9
 	err = delTbl.UpdateRecord(ctx, 9, types.MakeDatums(9, 9), types.MakeDatums(9, 10), touchedMap(delTbl))
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, writeTbl, 9, 9, false)
 	if err != nil {
 		return errors.Trace(err)
 	}
+
 	err = checkIndexExists(ctx, writeTbl, 10, 9, false)
 	if err != nil {
 		return errors.Trace(err)
diff --git a/plan/predicate_push_down.go b/plan/predicate_push_down.go
index 98fc21fdd1..43d81899ff 100644
--- a/plan/predicate_push_down.go
+++ b/plan/predicate_push_down.go
@@ -22,6 +22,17 @@ import (
 	"github.com/pingcap/tidb/util/types"
 )
 
+var (
+	inequalityFuncs = map[string]string{
+		ast.LT:   ast.LT,
+		ast.GT:   ast.GT,
+		ast.LE:   ast.LE,
+		ast.GE:   ast.GE,
+		ast.NE:   ast.NE,
+		ast.Like: ast.Like,
+	}
+)
+
 func addSelection(p Plan, child LogicalPlan, conditions []expression.Expression, allocator *idAllocator) error {
 	selection := &Selection{
 		Conditions:      conditions,
@@ -154,14 +165,7 @@ func propagateConstant(conditions []expression.Expression) []expression.Expressi
 	if len(multipleEqualities) == 0 {
 		return conditions
 	}
-	inequalityFuncs := map[string]string{
-		ast.LT:   ast.LT,
-		ast.GT:   ast.GT,
-		ast.LE:   ast.LE,
-		ast.GE:   ast.GE,
-		ast.NE:   ast.NE,
-		ast.Like: ast.Like,
-	}
+
 	type inequalityFactor struct {
 		FuncName string
 		Factor   []*expression.Constant
diff --git a/util/charset/charset.go b/util/charset/charset.go
index 149d3485ad..e755f4b66b 100644
--- a/util/charset/charset.go
+++ b/util/charset/charset.go
@@ -123,7 +123,7 @@ func GetDefaultCollation(charset string) (string, error) {
 	}
 	c, ok := charsets[charset]
 	if !ok {
-		return "", errors.Errorf("Unkown charset %s", charset)
+		return "", errors.Errorf("Unknown charset %s", charset)
 	}
 	return c.DefaultCollation.Name, nil
 }