t/800_regression/01_capture_request.t fails in presence of wildcard DNS records

[eserte]

Furl's test suite fails on many of my smokers like this:

#   Failed test at t/800_regression/01_capture_request.t line 10.
#          got: 'POST / HTTP/1.1
# Connection: keep-alive
# User-Agent: Furl::HTTP/3.14
# Host: example.com.local
# 
# '
#     expected: undef

#   Failed test at t/800_regression/01_capture_request.t line 11.
#          got: ''
#     expected: undef
# Looks like you failed 2 tests of 2.
t/800_regression/01_capture_request.t ........... 
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/2 subtests 

The problem is that the test hostname example.com.local, which obviously should not exist, actually resolves to something which has a web server running. This seems to happen if
a) the local DNS configuration does a fallback search for one or more domains (usually the default is to search for the local domain)
b) one of these domains has a wildcard DNS record
c) a webserver is running on the resolved address

It can be reproduced using the following Dockerfile (by experiments I found out that bing.com has a wildcard DNS record):

# docker build -t perl-test . && docker run -rm perl-test
FROM debian:11
RUN apt-get -y update
RUN apt-get -y --no-install-recommends install perl make cpanminus
RUN apt-get -y --no-install-recommends install libclass-accessor-lite-perl libencode-perl libhttp-parser-xs-perl
RUN apt-get -y --no-install-recommends install libtest-tcp-perl
ENV LOCALDOMAIN bing.com
CMD cpanm --test-only --verbose Furl

How can this be resolved? The LOCALDOMAIN environment variable is possibly Linux-specific, but setting it's value to something really non-existent might help on these systems. Additionally maybe do a gethostbyname call and check if it really returns nothing, otherwise skip the test.

[eserte]

Another possible solution: use a trailing dot in the invalid hostname. It seems that in this case the fallback to the search domains does not happen (at least this is the case on a debian:11 system). So

my $r=$f->post("http://example.com.local.");

should work.