If you are just attempting to get the response to respond with "true" or "false" depending on what's in the input, these values can be automatically correlated without any scripting. By default, DevTest ignores those values, because it is too easy to get false matches with such widely-used terms, but that behaviour can be changed by editing the file DEVTEST_HOME/lisa.properties (or copying these lines into DEVTEST_HOME/local.properties) and removing the "true, True, TRUE, false, False, FALSE," pieces:
# This allows you to exclude certain strings from being eligible
# for magic stringing.
lisa.magic.string.exclusion=Yes, YES, yes, No, NO, no, true, True, TRUE, false, False, FALSE, __NULL