Allow custom type converter to map empty String to custom default value for empty options #325
Description
Goal: provide the ability to specify a custom value to be used when a command line option is specified without any value.
@jesselong pointed out in #280 that with a small code change, users could specify a custom type converter that would assign the desired default value for options with no value.
Failing test to demonstrate the problem Jesse pointed out:
class ConversionForEmptyTest {
static class EmptyValueConverter implements ITypeConverter<Short> {
public Short convert(String value) throws Exception {
return value == null
? -1
: value.isEmpty() ? -2 : Short.valueOf(value);
}
}
@Test
public void testOptionEmptyValue() {
class Standard {
@Option(names = "-x", arity = "0..1", description = "may have empty value")
Short x;
}
try {
CommandLine.populateCommand(new Standard(), "-x");
fail("Expect exception for Short.valueOf(\"\")");
} catch (Exception expected) {
assertTrue(expected.getMessage(), expected.getMessage().contains("input string: \"\""));
}
Standard withValue1 = CommandLine.populateCommand(new Standard(), "-x=987");
assertEquals(Short.valueOf((short) 987), withValue1.x);
//------------------
class CustomConverter {
@Option(names = "-x", arity = "0..1", description = "may have empty value",
converter = EmptyValueConverter.class)
Short x;
}
CustomConverter withoutValue2 = CommandLine.populateCommand(new CustomConverter(), "-x");
assertEquals(Short.valueOf((short) -2), withoutValue2.x);
CustomConverter withValue2 = CommandLine.populateCommand(new CustomConverter(), "-x=987");
assertEquals(Short.valueOf((short) 987), withValue2.x);
}
}