follow the step

• Run npx jest --watch (should show unknown coverage)
• add test in '__ tests __/index.test.js' like this:

// ...
it('works with `import`', () => {
  expect(double(6)).toBe(12);
});

(should show unknown coverage)

• press key P, enter 'index'(should show correct)

• Run npx jest(should show correct)

issue: watch and coverage bug?