Does Blizzard PTR-test patches before they launch?

[d2e3x4-1441]

Dungeon Rewards Issue

Hello all - The team is investigating an issue and working on a fix with rewards not appearing for players who complete the Nightmare Dungeon for Akhan’s Grasp. The team will be rolling out a hotfix for this issue in the near future. We are also aware the normal Dungeons for Buried Halls and Endless Gates are not awarding rewards upon completion and are looking into a fix for that. Thank you for the reports on this.

No PTR in D4 unlike D3 , that’s my 2-cents.
PTR in D4 = 1st week of Seasons, normal aka non-casual gamers are the bugs explorer.