test(util): MockProtect when mocking multiple times

It is fine to use MockVariableValue to change a setting such as:

defer test.MockVariableValue(&setting.Mirror.Enabled, true)()

But when testing for errors and mocking a function, multiple variants
of the functions will be used, not just one. MockProtect a function
will make sure that when the test fails it always restores a sane
version of the function. For instance:

defer test.MockProtect(&mirror_service.AddPushMirrorRemote)()

mirror_service.AddPushMirrorRemote = mockOne
do some tests that may fail

mirror_service.AddPushMirrorRemote = mockTwo
do more tests that may fail

(cherry picked from commit 884b3c0f4b)

modules/test/utils.go

@@ -34,8 +34,15 @@ func IsNormalPageCompleted(s string) bool {
 	return strings.Contains(s, `<footer class="page-footer"`) && strings.Contains(s, `</html>`)
 }
 
+// use for global variables only
 func MockVariableValue[T any](p *T, v T) (reset func()) {
 	old := *p
 	*p = v
 	return func() { *p = old }
 }
+
+// use for global variables only
+func MockProtect[T any](p *T) (reset func()) {
+	old := *p
+	return func() { *p = old }
+}