By the way... if you have the cash spare & already have a monitor or TV with a hdmi or dvi port, a usb mouse & keyboard, then all you would need mac wise is the i5 mac mini. The are about £400 to €800 new & refurbished ones cost even less. You don't need official apple monitors mice / touchpads or keyboards to use them.
I believe the cheapest mac mini would be enough to test your games on as well as export them. Just saying, you don't need to splash out loads of money on a macbook pro, imac or mac pro. In the long run it probably wouldn't be a bad investment though if you are serious about developing games for multi-platforms. You can always install parallels VM (mac) as well to run windows or linux for additional testing.http://www.apple.com/uk/mac-mini/specs/
The cheapest option comes with 4GB ram & HD 5000 graphics card. The minimum recommended integrated graphics card is the HD 3000, however it is recommended to use dedicated graphics card instead, but the HD 5000 should be more than enough for 2D games.