Curious about handling of unmapped inputs

[Juanc1to]

I want to use input-remapper to set up my gamepad with the buttons as they are on an Xbox gamepad (that is, with A and B switched and X and Y switched). I have used the GUI to set up this mapping; when I test it (either in a game or using the Steam controller input test), the buttons are mapped correctly, but no other input from the gamepad is recognized. Is it the case that when using input-remapper, the user needs to provide a complete mapping for the device? I was hoping that there would be a way to say: if an input matches this map, then perform the mapping, but otherwise treat the input as normal. Is this input blocking behavior expected? If so, is there a way to configure it?

Also, as a side question, is there a good and robust way to test and confirm the results of a mapping? I would like to be able to see the result from a particular button or joystick press in some sort of debug output.