@Test
 public void should_throw_error_if_conversion_throws_NumberFormatException() {
   try {
     converter.toValue("0xZ", node);
     fail("Expecting a " + ValueConverterException.class.getName());
   } catch (ValueConverterException e) {
     assertThat(e.getMessage(), equalTo("Couldn't convert '0xZ' to long."));
     assertThat(e.getCause(), instanceOf(NumberFormatException.class));
   }
 }
 @Test
 public void should_throw_error_if_input_has_less_than_three_characters() {
   thrown.expect(ValueConverterException.class);
   thrown.expectMessage("Couldn't convert '0x' to long.");
   converter.toValue("0x", node);
 }
 @Test
 public void should_throw_error_if_input_is_empty() {
   thrown.expect(ValueConverterException.class);
   thrown.expectMessage("Couldn't convert empty string to long.");
   converter.toValue("", node);
 }