Running rake test on a Rails app that uses minitest only runs a single test. Is ruby deprecation a cause?

I'm currently trying to run tests in a Ruby on Rails app hosted with Puma instead of WeBrick. This is on Windows. Below is the error I get.

C:\Users\Ka\Desktop\code\developmentdatabase>bundle exec rake test
    ansi: 'gem install win32console' to use color on Windows
    RubyDep: WARNING: Your Ruby is outdated/buggy. (To disable warnings, set RUBY_DEP_GEM_SILENCE_WARNINGS=1)
    RubyDep: WARNING: Your Ruby is: 2.2.4 (buggy). Recommendation: install 2.2.5 or 2.3.1.
    Started with run options "-n=/^(EditTest\\#test_requires_a_log_message)$/" --seed 3480

      0/0: [===================================] 100% Time: 00:00:00, Time: 00:00:00
     FAIL["test_requires_a_log_message", EditTest, 0.7240425939962734]
     test_requires_a_log_message#EditTest (0.72s)
            Expected true to be nil or false
            test/models/edit_test.rb:45:in `block in <class:EditTest>'

      0/0: [===================================] 100% Time: 00:00:00, Time: 00:00:00
    WARNING: Your progress bar is currently at 0 out of 0 and cannot be incremented. In v2.0.0 this will become a ProgressBar::InvalidProgressError.
      0/0: [===================================] 100% Time: 00:00:00, Time: 00:00:00

    Finished in 0.72932s
    1 tests, 1 assertions, 1 failures, 0 errors, 0 skips
    20:01:43 - INFO - Run 'gem install win32console' to use color on Windows

I am unable to make my Rails app use the ruby 2.3.1, which I detail extensively in this thread which is still unanswered. But the gist is that ruby -v shows 2.3.1, but Rails won't use it.

Here's the Gemfile for the test environment:

group :test do
  gem 'minitest-rails'     # Test library
  gem 'minitest-rails-capybara' # Integration tests
  gem 'minitest-reporters' # For progress bar, etc.
  gem 'minitest-fail-fast' # End testing on first failure
  gem 'minitest-focus'     # One test at a time
  gem 'codeclimate-test-reporter', require: nil
  gem 'launchy'
  gem 'rake' # Specified for Travis CI
  gem 'webmock' # Disable network connections
end