Mocking classes or global functions in flutter/dart

Question

I am trying to understand how mocking works with dart and mockito. Image I have the below declarations:

void foo(){}

and similarly a class

class BarClass {
   void bar(){}
}

and then my widget accesses the first one directly as foo(); and the second one as BarClass().

What would be the way to mock these two? Should I be accessing them through something like getit to mock them properly or is there actually a way?

Answer 1

You can easily mock classes by creating a new class that implements the functionality of your old one using the mockito package

example code:

class MockBarClass extends Mock implements BarClass {}

you can mock methods of your BarClass in the following way:

final mock = MockBarClass();
when(() => mock.boo()).thenAnswer((_) {
    // your mocked response
    print("hello world");
});

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you can mock functions that are in no classes the same way:

when(boo()).thenReturn();

source by Remi Rousselet

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additional information if you ask yourself what's the difference between .thenReturn(...) and .thenAnswer((){...}):

I recommend reading this explanation: https://stackoverflow.com/a/36627077/12165405 (even though it's for java, the same applies for that flutter package)