Hi,

Are there any tools out there (preferably in rom or disk-format (readable by msx basic, msx-dos is unfortuantely one bridge too far for my emulator)) which test the aspects of the emulator? E.g. the compliancy of the z80 emulation, wether the vdp emulation behaves like it should, etc.

Usually a select number of games and demos is being used for this. Most notably Unknown Reality for its tight timing and special effects. A number of products has been used in MRC's emulator test.

I have some files if you wanted:
Keyboard
Simple stuff, but very nice to make a study.

BrMSX used ZEXALL test in order to check the Z80 implementation. I guess it is quite useful, 'cause the BrMSX CPU emulation was ahead of its time. Currently, Ricardo has joined the BlueMSX team. Maybe he could provide you some insight.

ZEXALL works on MSX-DOS, but it should also be possible to create a test stub for your Z80 module and run ZEXALL full throttle. It does not test everything though, eg. after satisfying ZEXALL I still had a bug left in my emu that made the game "Hype" lock up.
There aren't really any other emulation tests, unless you write your own. I suggest you to first focus on getting several 16/32KB Konami ROMs running well. Feel free to join #openmsx on IRC freenode for emudev discussion/questions btw.

Is there a (msx-) disk-image with that tool on it? I googled but i could only find binaries for the zx spectrum.

cpm.zip here, compatible with MSX-DOS
http://mdfs.net/Software/Z80/Exerciser/

You could build a megaROM file with the MSX-DOS files inside.
DSK2ROM