CamelCase, Snake_case and caterpillar-case with Guava

case.groovy

@Grab( 'com.google.guava:guava:16.0.1' )
import static com.google.common.base.CaseFormat.*
 
String.metaClass.caseFormat = { from, to ->
  from.to( to, delegate )
}
 
// From camelCase (LOWER_CAMEL) to SNAKE_CASE (UPPER_UNDERSCORE)
assert 'varName'.caseFormat( LOWER_CAMEL, UPPER_UNDERSCORE )       == 'VAR_NAME'

// From caterpillar-case (LOWER_HYPHEN) to CamelCase (UPPER_CAMEL)
assert 'var-name'.caseFormat( LOWER_HYPHEN, UPPER_CAMEL )          == 'VarName'

// from snake_case (LOWER_UNDERSCORE) to camelCase (LOWER_CAMEL)
assert 'var_name'.caseFormat( LOWER_UNDERSCORE, LOWER_CAMEL )      == 'varName'

// from SNAKE_CASE (UPPER_UNSERSCORE) to snake_case (LOWER_UNDERSCORE)
assert 'VAR_NAME'.caseFormat( UPPER_UNDERSCORE, LOWER_UNDERSCORE ) == 'var_name'

// from CamelCase (UPPER_CAMEL) to caterpillar-case (LOWER_HYPHEN)
assert 'VarName'.caseFormat( UPPER_CAMEL, LOWER_HYPHEN )           == 'var-name'