Update OngoingStubbing to take a Supplier<T>

Currently the OngoingStubbing interface only supports single values or varargs as part of the thenReturn() method. This method should be overloaded to include thenReturn(Supplier<T>). This feature will users testing streaming processes by being able to have new objects generated for each iteration through their pipeline.

[ZeLarpMaster]

Until it’s changed, because Answer is a functional interface, you can use thenAnswer and then like this:

private MyClass mockedClassInstance;
Supplier<Integer> intSupplier = () -> Random.nextInt(100);
when(mockedClassInstance.getInt()).then(i -> intSupplier.get())

Or

Function<?, Integer> answer = i -> Random.nextInt(100);
when(mockedClassInstance.getInt()).then(answer);

Or

when(mockedClassInstance.getInt()).then(i -> Random.nextInt(100));

[stephan-henningsen]

The latter of @ZeLarpMaster 's snippets helped out with the doAnswer() variant for spies. I completely forgot about the Answer interface, but it does the job here as well:

doAnswer( answer -> Random.nextInt(100) ).when(spy).getNiceInt();