code: func Emptyf(t TestingT, object interface{}, msg string, args ...interface{}) bool {
  	if h, ok := t.(tHelper); ok {
  		h.Helper()
  	}
  	return Empty(t, object, append([]interface{}{msg}, args...)...)
  }
docs: // Emptyf asserts that the specified object is empty.  I.e. nil, "", false, 0 or either
  // a slice or a channel with len == 0.
  //
  //  assert.Emptyf(t, obj, "error message %s", "formatted")