[PATCH 1/3] add cancel long message test

[Andrei Kholodnyi]

> Hi Andrei,
> I like these. ?Here are my comments.
> 1. There's a typo in an error message. ?The message says that we can't
> set the data mode to SSML, when in fact, we're trying to set it to
> text. ?I can fix this before pushing.

Yes, please do it.

> 2. If you want to use the text from the long_message test in multiple
> tests, it should be put in its own file.
> Perhaps teststrings.c, with a corresponding teststrings.h?
> Let me know what you think.

Yes, I like your idea, this makes much sense.
Would you mind sending a patch for it?

Andrei.