Is it possible to create custom .fit files (and view them) for testing data field functionality?

Hello friends,

I am trying to create a data field that acts as a power meter. I just want to fiddle with coding. But I find Garmin and related environment really hard to find my way around.

Is it possible create a .fit file that works as a linear (known) acceleration (or constant speed) and flat elevation (or certain gradient/s) and view/edit (monkey graph?) them in a certain way and run that .fit file through (simulator maybe?) my written data field and cross-verify the values I am getting,

Also, how do we monitor the data-flow, workspace input/output table (as in Matlab for example)?

As an addition, I would like to have a sub-menu that lets the user to pick several inputs (for data field calculation) from drop-down list, is this even possible? Do I need to write app instead of data field for that (I think yes)

Thank you very much,

Omur