Adding tests..

gistfile1.txt

morgo@ryzen:~/go/src/github.com/pingcap/tidb$ git diff
diff --git a/util/charset/charset_test.go b/util/charset/charset_test.go
index c400d97f..931b78ac 100644
--- a/util/charset/charset_test.go
+++ b/util/charset/charset_test.go
@@ -17,6 +17,8 @@ import (
        "testing"
 
        . "github.com/pingcap/check"
+       "github.com/pingcap/tidb/store/mockstore"
+       "github.com/pingcap/tidb/util/testkit"
        "github.com/pingcap/tidb/util/testleak"
 )
 
@@ -28,6 +30,7 @@ func TestT(t *testing.T) {
 var _ = Suite(&testCharsetSuite{})
 
 type testCharsetSuite struct {
+ store kv.Storage
 }
 
 func testValidCharset(c *C, charset string, collation string, expect bool) {
@@ -92,3 +95,10 @@ func (s *testCharsetSuite) TestGetDefaultCollation(c *C) {
                testGetDefaultCollation(c, tt.cs, tt.co, tt.succ)
        }
 }
+
+func (s *testCharsetSuite) TestConvertCharsetSQL(c *C) {
+
+  tk := testkit.NewTestKit(c, s.store)
+  tk.MustExec("SELECT CONVERT( CONVERT( 'xxx' USING ascii ) USING utf8mb4 ) AS xxx")
+
+}


morgo@ryzen:~/go/src/github.com/pingcap/tidb$ make dev
..
..
# github.com/pingcap/tidb/util/charset
import cycle not allowed in test
package github.com/pingcap/tidb/util/charset (test)
	imports github.com/pingcap/tidb/store/mockstore
	imports github.com/pingcap/tidb/store/mockstore/mocktikv
	imports github.com/pingcap/tidb/ast
	imports github.com/pingcap/tidb/model
	imports github.com/pingcap/tidb/types
	imports github.com/pingcap/tidb/util/charset

FAIL	github.com/pingcap/tidb/util/charset [setup failed]