China did a lot of things beside testing. Extremely strict lockdowns in affected areas, a near-total shutdown of passenger transport to and from affected region

China did a lot of things beside testing. Extremely strict lockdowns in affected areas, a near-total shutdown of passenger transport to and from affected regions and very rapid contact tracing. China isn't a unique outlier in this respect - South Korea and Singapore followed a similar strategy and got similar results. New Zealand faced a different set of circumstances and used a somewhat different strategy, but they're down to about a dozen cases per day.