It is being built using tooling which was originally provided by McDonnell Douglas for licence-production of the MD-90 in China. This is why it looks like the DC-9 series. It has exactly the same nose shape, cabin cross section, and tail.

So you could say that the design already made its first flight, in Long Beach, USA on 25 February 1965 – as the Douglas DC-9. The McDonnell Douglas MD-90 first flew in 1993. 😀

It is really a derivative of the MD-90, and not an original design.