As the world tries to get a handle on the coronavirus and emerge from paralyzing lockdowns, public health officials have repeated a mantra: “test, test, test.” Ben Dooley and Makiko Inoue write in the New York Times that Japan, however, went its own way, limiting tests to only the most severe cases as other countries raced to screen as many people as possible. Medical experts worried that the approach would blind the country to the spread of infection, allowing cases to explode and swamping hospitals. It hasn’t happened.