I can now answer my own question.
Covid testing at Yan'an hospital did continue through the holiday, and despite my wife's insistence that results were not available till next day I got them back same day.
I could not have done everything required without a Chinese speaking helper.
We had to start the day with registration.
It's 10 years since I've come to this hospital for anything so we were starting from scratch.
Creating a new patient record required my passport, which I brought with me.
The hospital's computer system did not have a big enough entry field for a foreign name. Once registered we simply lined up at another desk to get the requisition slip for the test.
We could have paid at the machines in the lobby but they didn't recognize things properly because of my name.
Those machines are also impossible to use by somebody who cannot READ Chinese.
Once paid we went outside to yet another line to get the testing swab/vial, then on to the 5th line for the actual test which was quick.
Getting the report back this afternoon was difficult even for my wife who can read Chinese.
The machines at the hospital are not exactly user friendly.
We did finally get the report.
I tested negative!