Connecting a device using Wi-fi and running automated tests on it sounds tricky, but actually it is not.
You need to follow these simple steps and BOOOOOOOOM...
Prerequisite: You need to have sdk and pc suite of specific brand installed on your machine. For eg. Kies for Samsung, Mobomarket for micromax and others.
1. Connect the device using USB.
2. Check if your laptop and mobile are connected to same WiFi network.
3. Run this command in command prompt.
adb tcpip 5555
4. Remove USB cable. And check IP through which your device is connected to wi-fi.
5. Run this command in command prompt
adb connect <ip>
6. If it says connected, then run your script and it will be executed over wifi. You can check the status using "adb devices" command.