There're already quite a few katas about drawing triangles/pyramids/diamonds, and this one doesn't seem to be original enough compared to those.

Added random tests.

Converted to snake_case (and accepts old solutions).

3 test cases = Lame.

Not an issue

maybe first and last string wouldn't consist of spaces

Good insight. I'm not printing anything to the console though.

are you sure you aren't simply printing too much data to the console? (too much assertion messages (like in python) lead to the same thing)

Swift translation kumitted. Anyone know how to add random tests in swift? I've tried several approaches, looked at other katas in swift using random tests, and for some reason I always get SIGILL's and SIGTRAP's.

Nice little kata. Thank you for making this!

I never said tat it's "invalid", just that it seems not the better one to me. ;)

snake_case is the preferred way of naming functions in Python. It should be bow_tie.
https://www.python.org/dev/peps/pep-0008/

I'd say a line feed at the end is a valid choice. For instance, unlines in Haskell adds it in the end.