Thanks, you were right. Solution was to mark all methods as public.

Are you sure your male method is visible? Maybe mark it public explicitly?
The {} in the error message should actually be 1. This is corrected: you should reset/reload the tests to see the difference.

hey, I dont get why this pops up

Should_be_possible_to_create_a_family_instance_having_the_expected_methods
Method male should be defined with {} arguments of type String.
expected: but was:

my method:
boolean male(String name){
if(females.contains(name)) return false;
else {
males.add(name);
return true;
}
}