ts-mockito.ts

import { mock, instance, when, verify, anything } from 'ts-mockito';

const  mockedFoo: Foo = mock(Foo);

// stub method before execution
when(mockedFoo.getBar(3)).thenReturn('three');

// Getting instance from mock
const foo: Foo = instance(mockedFoo);

// Using instance in source code
foo.getBar(3);
foo.getBar(5);

// Explicit, readable verification
verify(mockedFoo.getBar(3)).called();
verify(mockedFoo.getBar(anything())).called();

// parameter validation
verify(mockedFoo.getBar(4)).never();