@Test
public void parseDoubleNull() {

    assertEquals(-2, Numbers.parseDoubleNull("-2"), 0.1);
    assertEquals(-1, Numbers.parseDoubleNull("-1"), 0.1);
    assertEquals(0, Numbers.parseDoubleNull("0"), 0.1);
    assertEquals(1, Numbers.parseDoubleNull("1"), 0.1);
    assertEquals(2, Numbers.parseDoubleNull("2"), 0.1);
    assertNull(Numbers.parseDoubleNull(""));
    assertEquals(0.0, Numbers.parseDoubleNull("0.0"), 0.1);
    assertEquals(0.1, Numbers.parseDoubleNull("0.1"), 0.1);
    assertNull(Numbers.parseDoubleNull("X"));
    assertNull(Numbers.parseDoubleNull("NaN"));
    assertNull(Numbers.parseDoubleNull(null));
}