According to :
I would like to move my microwave from the kitchen countertop into a
spacious cabinet to free up the counter. There is currently a 14ga
wire running to that cabinet from a wall switch (prior owner intended
to install accent lighting in glass-fronted portion of cabinet. Is it
safe to run a microwave on a circuit/outlet controlled by a wall
switch? How do I tell if the switch is 'rated' for a certain power
draw? I would obviously install a GFI outlet.

Walls switches are rated for 15A. That's more than adequate for a
microwave. Microwaves aren't motors, so you don't need to get motor-rated
switches.

It'll be an annoyance to lose all the settings on the microwave whenever
anybody hits the switch. Remove it and jumper the wires, covering
the hole with a blank plate if you're worried.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.