I don't think such a simulator exists, and I don't think there's any need for one.
MIDI is standard: if the application works with a given MIDI message, and the Arduino can send out that exact message, everything will work fine.
Sending MIDI is really easy using my MIDI Controller library, or its successor the Control Surface Library.
On the topic of "simulators", the approach I'm using is to have unit tests that run on my computer. I compile these test, my Arduino library code, and an Arduino mocking library on my laptop, and run the tests.
When all tests pass, and all examples compile for Arduino (using arduino-builder), I can be pretty confident that it will work on the Arduino itself as well.
You can see an example of one of these tests here:
test/MIDI_Outputs/test-NoteButton.cpp
There are many MIDI "monitor" applications available that can create virtual MIDI ports and log and send data to other MIDI applications. You can use those to check what MIDI messages you have to send to the music software. However, this shouldn't be necessary, because the MIDI Controller and Control Surface libraries already send the correct messages (for most applications), and you can also check the MIDI documentation for your particular piece of software.
Pieter