message: test: serialize tmp-helper test cases
diff: @@ -12,13 +12,13 @@ test.after.always(async () => {
  }
  });
  -test('no permission', t => {
  +test.serial('no permission', t => {
  t.throws(() => {
  const file = new TmpFile('/System');
  });
  });
  -test('should work', async t => {
  +test.serial('should work', async t => {
  const factory = createTmpFactory('tmp-helper-test-folder');
  const tmp = factory('tmp1.txt');
  @@ -28,7 +28,7 @@ test('should work', async t => {
  t.is(await tmp.getContent(), '123456abcdef');
  });
  -test('should work with maxAge 1', async t => {
  +test.serial('should work with maxAge 1', async t => {
  const factory = createTmpFactory('tmp-helper-test-folder');
  const tmp = factory('tmp2.txt', 50);
  @@ -42,7 +42,7 @@ test('should work with maxAge 1', async t => {
  t.is(await tmp.getContent(), '123456abcdefg');
  });
  -test('should work with maxAge 2', async t => {
  +test.serial('should work with maxAge 2', async t => {
  const factory = createTmpFactory('tmp-helper-test-folder');
  const tmp = factory('tmp3.txt', 1000);
  