China loves the distraction of a buffer State. They have moved on from pure communism and are soon to be the #1 economy in the world. Meanwhile, NK is trapped in the last century, and its people are suffering greatly.
The Chinese are becoming more and more hawkish, due to increased nationalism attributed to their self-awareness of their rising status as a superpower.
The leadership does not want a conflict with the US anymore than we want a conflict with China. But they are beginning to test our defense commitments to Japan and Taiwan. They are developing military technology that is not quite as good as the United States', but is made much cheaper.
On the other side of the coin, they do not want to give SK and the US an excuse to take out the NK leadership and unify the peninsula with a western-backed leadership.
Things will change dramatically based on the yield of the upcoming NK test. If it is highly enriched uranium, it will steal the spotlight from drones, guns, and Iran. If it is two plutonium bombs set off simultaneously to try to fool seismic and satellite sensors, then they are still where they were 7 years ago. Given they have received help from other nations, I doubt they have remained that stagnant as far as nuclear weapons technology.