@Test
public void on_activate_clicked_should_enable_beacons_and_finish_activity_if_all_configurations_are_satisfied() {
    //PREPARE
    ConfigurationRequirementState satisfiedConfig1 = new ConfigurationRequirementStateBuilder()
            .withStatus(ConfigurationRequirementState.Status.SATISFIED)
            .build();

    ConfigurationRequirementState satisfiedConfig2 = new ConfigurationRequirementStateBuilder()
            .withStatus(ConfigurationRequirementState.Status.SATISFIED)
            .build();

    ConfigurationState configurationState = ConfigurationState.from(Arrays.asList(satisfiedConfig1, satisfiedConfig2));

    when(configurationChecker.checkConfiguration()).thenReturn(just(configurationState2));

    //RUN
    presenter.onActivateClicked();

    //ASSERT
    verify(userSettings).enableBeacons();
    verify(view).showBeaconsEnabled();
    verify(view).finishActivity();
}

@Override
public void onActivateClicked() {
    subscribe(configurationChecker.checkConfiguration()
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeOn(AndroidSchedulers.mainThread())
            .flatMap(configState -> Observable.from(configState.requirements()))
            .filter(requirementState -> requirementState.status() != ConfigurationRequirementState.Status.SATISFIED)
            .toList()
            .subscribe(notSatisfiedItems -> { <---- NULLPOINTER IN THIS LINE
                if(notSatisfiedItems.size() == 0) {
                    enableBeaconsAndFinishActivity();
                } else {
                    userRequestedConfiguration = true;
                    notSatisfiedConfigurationsCount = notSatisfiedItems.size();

                    requestConfigurationWithConfirmDialog(notSatisfiedItems.get(0));
                }
            }));
}