test: fix unstable TestIssue20658 (pingcap#24425) (pingcap#24466)

executor/aggregate_test.go

@@ -1307,6 +1307,7 @@ func (s *testSuiteAgg) TestIssue20658(c *C) {
 	for _, sql := range sqls {
 		var expected [][]interface{}
 		for _, con := range concurrencies {
+			comment := Commentf("sql: %s; concurrency: %d", sql, con)
 			tk.MustExec(fmt.Sprintf("set @@tidb_streamagg_concurrency=%d;", con))
 			if con == 1 {
 				expected = tk.MustQuery(sql).Sort().Rows()
@@ -1320,16 +1321,20 @@ func (s *testSuiteAgg) TestIssue20658(c *C) {
 						break
 					}
 				}
-				c.Assert(ok, Equals, true)
+				c.Assert(ok, Equals, true, comment)
 				rows := tk.MustQuery(sql).Sort().Rows()
 
-				c.Assert(len(rows), Equals, len(expected))
+				c.Assert(len(rows), Equals, len(expected), comment)
 				for i := range rows {
-					v1, err := strconv.ParseFloat(rows[i][0].(string), 64)
-					c.Assert(err, IsNil)
-					v2, err := strconv.ParseFloat(expected[i][0].(string), 64)
-					c.Assert(err, IsNil)
-					c.Assert(math.Abs(v1-v2), Less, 1e-3)
+					rowStr, expStr := rows[i][0].(string), expected[i][0].(string)
+					if rowStr == "<nil>" && expStr == "<nil>" {
+						continue
+					}
+					v1, err := strconv.ParseFloat(rowStr, 64)
+					c.Assert(err, IsNil, comment)
+					v2, err := strconv.ParseFloat(expStr, 64)
+					c.Assert(err, IsNil, comment)
+					c.Assert(math.Abs(v1-v2), Less, 1e-3, comment)
 				}
 			}
 		}