They do have an alliance: https://www.cfr.org/article/china-russia-and-ukraine-october...

What the words are worth in a time of need remains to be seen. Neither side is exactly trustworthy :)

From what I understood, China was completely blindsided by the invasion (given that it happened so soon after the announcement of the alliance), and actually somewhat pissed. Russia basically used their alliance as insurance against a fully global sanctions regime, and China had to stick around to save face.

Blessedly we're citizens of good and noble western countries that are supremely trustworthy and that would never ever renege on a deal or fight unjust wars.