How can I mock the mockito dart indexing operator?
I am writing a unit test in which I need to mock a JsObject so that I don't have to do actual javascript interaction in my test. However, I am using the indexing operator []
to access the field in my JsObject. I am using the dart mockito library https://github.com/fibulwinter/dart-mockito for mocking, and I cannot find how I am fooling the behavior of the operators on the mocking object.
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Mockito makes trimming very easy, with the stubbing index operator working just like wrapping any other method. When rendering, you want to stub the index operator of the following class:
class IndexTest {
operator[] (String value);
}
In the first step, we create a layout for this class:
class MockIndexTest extends Mock implements IndexTest {
noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
}
Now in your test, you can set the return values that you expect for invocations using the index operator:
test('Test', () {
final t = new MockIndexTest();
// Set return values
when(t[any]).thenReturn(0); // 1
when(t['one']).thenReturn(1); // 2
when(t['two']).thenReturn(2); // 3
// Check return values
expect(t['one'], equals(1));
expect(t['two'], equals(2));
expect(t['something else'], equals(0));
});
Without interrupting the call, it always returns null
. With the value any
provided by mockito, you can set a default return value for calls with any argument (see 1). You can also set the return value for a specific set of parameters (see 2 and 3). Before setting certain parameters, you must set the default value.
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