Do not use DeepEqual to compare slices in test.

This wraps DeepEqual with a helper that considers nil slices and empty
slices to be equal.

Scheduler code might use a nil slice or empty slice to represent an
empty list, so tests should not be sensitive to the difference.  Tests
could fail because DeepEqual considers nil to be different from an empty
slice.

pkg/scheduler/core/equivalence_cache_test.go

@@ -378,6 +378,14 @@ func TestUpdateResult(t *testing.T) {
 	}
 }
 
+// slicesEqual wraps reflect.DeepEqual, but returns true when comparing nil and empty slice.
+func slicesEqual(a, b []algorithm.PredicateFailureReason) bool {
+	if len(a) == 0 && len(b) == 0 {
+		return true
+	}
+	return reflect.DeepEqual(a, b)
+}
+
 func TestLookupResult(t *testing.T) {
 	tests := []struct {
 		name                              string
@@ -504,9 +512,9 @@ func TestLookupResult(t *testing.T) {
 		if fit != test.expectedPredicateItem.fit {
 			t.Errorf("Failed: %s, expected fit: %v, but got: %v", test.name, test.cachedItem.fit, fit)
 		}
-		if !reflect.DeepEqual(reasons, test.expectedPredicateItem.reasons) {
+		if !slicesEqual(reasons, test.expectedPredicateItem.reasons) {
 			t.Errorf("Failed: %s, expected reasons: %v, but got: %v",
-				test.name, test.cachedItem.reasons, reasons)
+				test.name, test.expectedPredicateItem.reasons, reasons)
 		}
 	}
 }