test.mm

- (dispatch_block_t)_enableSpeakers
{
    ++self->_interruptCount;
    UInt32 const speakerOverride = kAudioSessionOverrideAudioRoute_Speaker;
    AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute,
                            sizeof(speakerOverride),
                            &speakerOverride);

    __block BOOL disabled = NO;
    return ^{
        NSAssert(!disabled, @"Tried to call speaker route override disable block repeatedly!");
        disabled = YES;
        
        UInt32 const disableOverride = kAudioSessionOverrideAudioRoute_None;
        AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute,
                                sizeof(disableOverride),
                                &disableOverride);
        
        --self->_interruptCount;
    };
}

- (void)enableSpeakersForDuration:(NSTimeInterval)aSeconds
{
    AfterDelay(aSeconds, [self _enableSpeakers]); // _enableSpeakers returns a block that disables the override again
}