Does MacBook Air laptop is enough for Automation Testing I'm wanna use Xcode and Android Studio with Appium to do a Mobile Automation Testing. Then for Websites I'm gonna use selenium stuffs. Additionally pycharm &amp; IntelliJ for some test scripts. 
For these above, which Mac (Spec) is good to buy. 
I'm actually planning to buy MacBook Air.
Sure. It’s a fabulous CPU, blazing fast storage and faster than most Macs a year old in terms of all the benchmarks you’ll need for getting started developing. 

Great value and it holds resale value much better than more pricey Macs. Unless you have a great value used Mac, get this and work the heck out of it. Assuming you ever find it’s slowing you down, you’ll know what you need and can sell this and roll the resale into whatever new tool you chose. 

I do what you mention on a 2105 MacBook with 1.1 GHz m3 CPU. The Air won’t be the reason you’re held back from getting real work done.