@Test
public void parseDouble() {

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