@Test
public void testEmpty() {

    try {
        valueConverter.convertValue(valueFactory.createLiteral(""), null, type);
        TestCase.fail("Empty string should cause ValueConversionException");
    } catch (ValueConversionException e) {
        TestCase.assertTrue("Cause of error should have been NumberFormatException",
                e.getCause() instanceof NumberFormatException);
    }
}