Testing

The koin_test package brings you small but powerful tools to test your Koin application.

Getting your components

Just import the koin_testpackage, and you will be able to unlock KoinComponent & testing features:

  • inject() - lazy inject an instance
  • get() - retrieve an instance

Given the definitions below:

final appModule = module()..single((s) => ComponentA());

We can write the test below:

void main() {
test('MyTest', () {
startKoin((app) {
app.module(appModule);
});
// Lazy inject property
var componentA = inject<ComponentA>();
expect(componentA, isNotNull);
});
}

you can use the setUp tearDown to start/stop your Koin context:

setUp((){
startKoin((app) {
app.module(myModule);
});

Checking your modules

You can easily test module definitions.

Let's write our check test as follow:

  • test modules with testModules() function

Let's check our modules.

void main(){
testModules('moduleChecktest - shoud be a valid module',[myModule1,myModule2]);
}

Mocking on the fly

Once you have import koin_test, you can use the declare function to declare mocks & behavior on the fly:

class ComponentA {
String sayHello() => 'Hello';
}
class ComponentMock extends Mock implements ComponentA {}
void main() {
setUp(() {
startKoin((app) {
app.module(module()
..single((s) => ComponentA()));
});
});
koinTearDown();
test('declareMock with KoinTest', () {
var componentAMock = ComponentMock();
when(componentAMock.sayHello()).thenReturn('Hello Mock');
// declare a mock instance to ComponentA.
declare<ComponentA>(componentAMock);
// retrieve mock, same as variable above
expect(get<ComponentA>().sayHello(), 'Hello Mock');
});
}

Starting & stopping for tests

Take attention to stop your koin instance (if you use startKoin in your tests) between every test. Else be sure to use koinApplication, for local koin instances or stopKoin() to stop the current global instance.

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