[DRE-maint] Bug#888191: ruby-powerpack: FTBFS on ruby2.5: Error: expect([].sum).to be_nil

[Chris West (Faux)]

Source: ruby-powerpack
Version: 0.1.1-3
Severity: important
User: debian-ruby at lists.debian.org
Usertags: ruby2.5

Dear Maintainer,

This package fails to build against ruby2.5. Soon, there will
be a transition to ruby2.5, and this package will FTBFS in sid.

There may be some details on the wiki about common problems:
https://wiki.debian.org/Teams/Ruby/Ruby25Transition

Build log excerpt:


Failures:

  1) Enumerable#sum returns nil when invoked on an empty collection
     Failure/Error: expect([].sum).to be_nil

       expected: nil
            got: 0
     # ./spec/powerpack/enumerable/sum_spec.rb:9:in `block (2 levels) in <top (required)>'

Finished in 0.05947 seconds (files took 0.21147 seconds to load)
102 examples, 1 failure

Failed examples:

rspec ./spec/powerpack/enumerable/sum_spec.rb:8 # Enumerable#sum returns nil when invoked on an empty collection

/usr/bin/ruby2.5 /usr/bin/rspec --pattern ./spec/\*\*/\*_spec.rb --format documentation failed
ERROR: Test "ruby2.5" failed. Exiting.
dh_auto_install: dh_ruby --install /build/ruby-powerpack-0.1.1/debian/ruby-powerpack returned exit code 1
debian/rules:6: recipe for target 'binary' failed
make: *** [binary] Error 1
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2

Full build log:
https://rbuild.fau.xxx/2018-01-23/ruby-powerpack.log

Please fix it!

Cheers,
Chris.