A pilot entering the pattern at a non towered airport reported a NMAC with head on traffic climbing to their altitude.

Narrative

I was on a maintenance flight in Aircraft X from ZZZ to ZZZ1; then back to ZZZ. On approach to ZZZ I came in over midfield at 2200 feet. 1000 feet above pattern altitude to enter on a 45 degree for the downwind for runway XX. While directly over midfield; my TA from ADS-B came on telling me there was traffic. Aircraft Y was approaching me head on; same altitude; climbing and looked like was turning to his right straight into me. I took evasive action by rapidly decreasing altitude. Approximate vertical distance was about 100 feet. I then continued my approach and landed on runway XX at ZZZ.I believe the problem was caused by poor airmanship of the other pilot. I did not hear any radio calls being made by the pilot and there was no reason for him being there in manner in which he was approaching the airfield. The pattern was busy that day. The standard pattern entry at ZZZ is to overfly midfield 1000 feet above pattern altitude if coming from the opposite side of the pattern. Practicing standard entry maneuvers into uncontrolled airfields would help mitigate these kinds of situations.