MagicHaskeller[0] (which seems to sadly be offline at present) is a similar project that infers Haskell functions from properties like

   reverse "abcde" = "edcba"

Other, older projects include Exference[1] and Djinn[2], in decreasing order of power.

Also, this is really similar to how Idris and Agda work, except they use expressive types to generate the code (using the Emacs modes) rather than test cases.

[0]: http://nautilus.cs.miyazaki-u.ac.jp/cgi-bin/MagicHaskeller.c...

[1]: https://github.com/lspitzner/exference/

[2]: http://www.hedonisticlearning.com/djinn/