scheduler: make ApplyFeatureGates() stateless

pkg/scheduler/algorithmprovider/defaults/defaults.go

@@ -57,7 +57,11 @@ func defaultPredicates() sets.String {
 }
 
 // ApplyFeatureGates applies algorithm by feature gates.
-func ApplyFeatureGates() {
+// The returned function is used to restore the state of registered predicates/priorities
+// when this function is called, and should be called in tests which may modify the value
+// of a feature gate temporarily.
+func ApplyFeatureGates() (restore func()) {
+	snapshot := factory.Copy()
 	if utilfeature.DefaultFeatureGate.Enabled(features.TaintNodesByCondition) {
 		// Remove "CheckNodeCondition", "CheckNodeMemoryPressure", "CheckNodePIDPressure"
 		// and "CheckNodeDiskPressure" predicates
@@ -105,6 +109,11 @@ func ApplyFeatureGates() {
 		// Register the priority function to specific provider too.
 		factory.InsertPriorityKeyToAlgorithmProviderMap(factory.RegisterPriorityMapReduceFunction(priorities.ResourceLimitsPriority, priorities.ResourceLimitsPriorityMap, nil, 1))
 	}
+
+	restore = func() {
+		factory.Apply(snapshot)
+	}
+	return
 }
 
 func registerAlgorithmProvider(predSet, priSet sets.String) {

pkg/scheduler/algorithmprovider/plugins.go

@@ -21,6 +21,6 @@ import (
 )
 
 // ApplyFeatureGates applies algorithm by feature gates.
-func ApplyFeatureGates() {
-	defaults.ApplyFeatureGates()
+func ApplyFeatureGates() func() {
+	return defaults.ApplyFeatureGates()
 }

pkg/scheduler/algorithmprovider/plugins_test.go

@@ -94,7 +94,7 @@ func TestApplyFeatureGates(t *testing.T) {
 	// Apply features for algorithm providers.
 	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.TaintNodesByCondition, true)()
 
-	ApplyFeatureGates()
+	defer ApplyFeatureGates()()
 
 	for _, pn := range algorithmProviderNames {
 		t.Run(pn, func(t *testing.T) {