I’m facing an issue with resetting a singleton
object in a Flutter test
.
I have the following limitations that need to be taken into consideration while solving the problem:
1- The
_singleton
variable must remainfinal
.2- I cannot define a
static
orpublic
method to change the value
of_lock
due to reduced security rules.3- I must solve the problem within the
flutter_test
package and not
any other package likemockito
.
Here’s the minimal code for the Singleton
class :
class Singleton {
static final Singleton _singleton = Singleton._internal();
bool _lock = false;
Singleton._internal();
factory Singleton() {
assert(!_singleton._lock, "Singleton class has already been instantiated.");
_singleton._lock = true;
return _singleton;
}
static Singleton get instance => _singleton;
}
And here’s the test
that I’m trying to fix:
void main() {
group('Singleton', () {
test('should return the same instance', () {
final instance1 = Singleton.instance;
final instance2 = Singleton.instance;
expect(instance1, same(instance2));
});
test('should throw an error when instantiated twice', () {
Singleton(); // first instantiation
expect(() => Singleton(), throwsA(isA<AssertionError>()));
});
test('should rest singleton and test pass', () {
Singleton();
expect(() => Singleton(), throwsA(isA<AssertionError>()));
});
});
}
My question is: How can I reset
the Singleton
object in the should reset the singleton and pass the test test while still adhering to the above limitations? .
2
Answers
I'm pleased to report that I've successfully resolved my issue.
I was able to devise a solution by creating a
public method
that detects the currenttest environment
.In this case, except in the object test mode, it will not be able to be reset .add below code to singleton class:
set changes in test code:
If code is being run in a
web
environment, the program will continue to execute without encountering any errors.You can call the resetitsingleton function whenever you need to reset the state of the singleton object in your app.