Add test_dependency from mruby-io to mruby-time.
MODIFY
mrbgems/mruby-io/mrbgem.rake
mrbgems/mruby-io/mrbgem.rake
@@ -14,4 +14,5 @@ MRuby::Gem::Specification.new('mruby-io') do |spec|
if build.kind_of?(MRuby::CrossBuild) && %w(x86_64-w64-mingw32 i686-w64-mingw32).include?(build.host_target)
spec.linker.libraries += ['ws2_32']
end
+ spec.add_test_dependency 'mruby-time', core: 'mruby-time'
end

Add test_dependency from mruby-io to mruby-time.