They've had trouble doing this for years. The PLA has three competing military strategies vying for funds. Because he feels the Chinese have no chance of succeeding, while merely trying this strategy will so drain their resources as to marginalize all other potential threats. Computer viruses, sea mines, cruise or ballistic missiles and the Gerald Bull super-guns make up this approach. This assumes the Chinese economy develops to the point where they can afford such toys.
Tests are expensive and an embarrassing lost of face if they uncover failure.
Testing is kept unrealistic, and done as few times as possible, as a result. A good historical analog is the performance of both American torpedoes and the U.S. Naval Ordnance branch early in WW2. The foreign joint venture companies are raiding the Chinese military industrial complex for talented engineers and managers. That is a major drag on any Chinese military buildup and ensures what they build cannot be maintained. This is a fact the Chinese are well aware of in light of their reaction to the possibility of American strategic missile defenses.