is there a special TZX test image somewhere?

[Lethargeek]

i mean, the one using all the block types (with or without deprecated ones) and giving a message in the end if it was loaded properly

[spider]

Not that I am aware of.

You could I suppose make one but .tzx does support a lot and I think (imo) unless you're willing to maybe put various loaders onto it, might be a lot of work.

In theory ( ! ) you only maybe need one at standard baud, perhaps one each at say 2500 and 3500 ?

I may of missed what you're trying to do.

[Seven.FFF]

It would be useful for emulator authors to test emulators.