make TestGetAllByKey stable

Signed-off-by: lhy1024 <admin@liudos.us>

tests/server/api/rule_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/tikv/pd/pkg/errs"
 	"github.com/tikv/pd/pkg/schedule/labeler"
 	"github.com/tikv/pd/pkg/schedule/placement"
+	"github.com/tikv/pd/pkg/utils/testutil"
 	tu "github.com/tikv/pd/pkg/utils/testutil"
 	"github.com/tikv/pd/server/config"
 	"github.com/tikv/pd/tests"
@@ -565,8 +566,10 @@ func (suite *ruleTestSuite) checkGetAllByKey(cluster *tests.TestCluster) {
 		var resp []*placement.Rule
 		url := fmt.Sprintf("%s/rules/key/%s", urlPrefix, testCase.key)
 		if testCase.success {
-			err = tu.ReadGetJSON(re, testDialClient, url, &resp)
-			suite.Len(resp, testCase.respSize)
+			testutil.Eventually(re, func() bool {
+				err = tu.ReadGetJSON(re, testDialClient, url, &resp)
+				return len(resp) == testCase.respSize
+			})
 		} else {
 			err = tu.CheckGetJSON(testDialClient, url, nil, tu.Status(re, testCase.code))
 		}