The issue found looks similar to https://stackoverflow.com/questions/55631720/simplecov-rcov-is-throwing-a-encodingundefinedconversionerror.
Also https://github.com/fguillen/simplecov-rcov/issues/20 suggest may be related to file open permissions set.
When running rspec test with `bundle exec rake spec` the following stack traces is seen.
```
Traceback (most recent call last):
27: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/defaults.rb:27:in `block in <top (required)>'
26: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov.rb:202:in `at_exit_behavior'
25: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov.rb:214:in `run_exit_tasks!'
24: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/configuration.rb:196:in `block in at_exit'
23: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/result.rb:49:in `format!'
22: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-html-0.12.2/lib/simplecov-html.rb:28:in `format'
21: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-html-0.12.2/lib/simplecov-html.rb:28:in `open'
20: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-html-0.12.2/lib/simplecov-html.rb:29:in `block in format'
19: from /home/msfuser/.rvm/rubies/ruby-2.6.5/lib/ruby/2.6.0/erb.rb:901:in `result'
18: from /home/msfuser/.rvm/rubies/ruby-2.6.5/lib/ruby/2.6.0/erb.rb:901:in `eval'
17: from (erb):8:in `block in format'
16: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:73:in `covered_percent'
15: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:27:in `coverage_statistics'
14: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:104:in `compute_coverage_statistics'
13: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:104:in `each_with_object'
12: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:104:in `each'
11: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/file_list.rb:105:in `block in compute_coverage_statistics'
10: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:35:in `coverage_statistics'
9: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:333:in `line_coverage_statistics'
8: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:241:in `lines_strength'
7: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:43:in `lines'
6: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:224:in `build_lines'
5: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:28:in `src'
4: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:181:in `load_source'
3: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:181:in `open'
2: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:189:in `block in load_source'
1: from /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:202:in `read_lines'
/home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/simplecov-0.18.5/lib/simplecov/source_file.rb:202:in `readlines': U+2713 from UTF-8 to ASCII-8BIT (Encoding::UndefinedConversionError)
/home/msfuser/.rvm/rubies/ruby-2.6.5/bin/ruby -I/home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/rspec-core-3.9.1/lib:/home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/rspec-support-3.9.2/lib /home/msfuser/.rvm/gems/ruby-2.6.5@metasploit-framework/gems/rspec-core-3.9.1/exe/rspec --pattern spec/\*\*\{,/\*/\*\*\}/\*_spec.rb failed
```
Since we expect to support non-ASCII characters in some locations locking the version until a solution is found. The issue linked above suggest that a test helper may be able to override the open permissions, however since `rake spec` in Travis runs without the simplecov gem this may require some finesse to implement.
