@Test
public void testSort() {

  Asserts.assertArrayEquals(Operators.sort());
  Asserts.assertArrayEquals(Operators.sort("="), "=");
  Asserts.assertArrayEquals(Operators.sort("+", "+=", "+", ""), "+=", "+");
  Asserts.assertArrayEquals(Operators.sort("+", "+=", "+++", "-"), "-", "+=", "+++", "+");
  Asserts.assertArrayEquals(Operators.sort("+", "+=", "+++", "-", "-="),
      "-=", "-", "+=", "+++", "+");
}