feat(trace): add trace test helpers (#3108)

core/stores/sqlx/sqlconn_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/DATA-DOG/go-sqlmock"
 	"github.com/stretchr/testify/assert"
 	"github.com/zeromicro/go-zero/core/logx"
+	"github.com/zeromicro/go-zero/core/trace/tracetest"
 )
 
 const mockedDatasource = "sqlmock"
@@ -17,6 +18,7 @@ func init() {
 }
 
 func TestSqlConn(t *testing.T) {
+	me := tracetest.NewInMemoryExporter(t)
 	mock, err := buildConn()
 	assert.Nil(t, err)
 	mock.ExpectExec("any")
@@ -49,6 +51,7 @@ func TestSqlConn(t *testing.T) {
 	assert.NotNil(t, badConn.Transact(func(session Session) error {
 		return nil
 	}))
+	assert.Equal(t, 14, len(me.GetSpans()))
 }
 
 func buildConn() (mock sqlmock.Sqlmock, err error) {