### Question:
CallableNullaryFunctionAdapter implements NullaryFunction<T> { public static <T> NullaryFunction<T> callableNullaryFunction(Callable<? extends T> callable) { return new CallableNullaryFunctionAdapter<T>(callable); } CallableNullaryFunctionAdapter(Callable<? extends T> callable); static NullaryFunction<T> callableNullaryFunction(Callable<? extends T> callable); @Override T call();  }### Answer:
@Test(expected = NullPointerException.class) public void shouldThrowNullPointerExceptionIfCallableSuppliedToCallableNullaryFunctionStaticConstructorIsNull() throws Exception { Callable<String> callable = null; callableNullaryFunction(callable); }