Rules type must implement Rule interface

The interface changed in kubernetes#6196 but the Rules class didn't

cluster-autoscaler/simulator/drainability/rules/rules.go

@@ -79,6 +79,10 @@ func Default(deleteOptions options.NodeDeleteOptions) Rules {
 // Rules defines operations on a collections of rules.
 type Rules []Rule
 
+func (r *Rules) Name() string {
+	return "Rules"
+}
+
 // Drainable determines whether a given pod is drainable according to the
 // specified set of rules.
 func (rs Rules) Drainable(drainCtx *drainability.DrainContext, pod *apiv1.Pod) drainability.Status {

cluster-autoscaler/simulator/drainability/rules/rules_test.go

@@ -25,6 +25,9 @@ import (
 	"k8s.io/autoscaler/cluster-autoscaler/utils/drain"
 )
 
+// Ensure that Rules type implements the Rule interface
+var _ Rule = &Rules{}
+
 func TestDrainable(t *testing.T) {
 	for desc, tc := range map[string]struct {
 		rules Rules