Can't run tests because of SyntaxError

[dersnek]

I've cloned master branch, done everything mentioned in Development Environment Setup, but when I try to run tests with:

bundle exec rake

I get the following error:

Running tests with `DB=mysql`
/home/mark/.rvm/rubies/ruby-2.2.10/bin/ruby -I/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-core-3.9.0/lib:/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-support-3.9.0/lib /home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-core-3.9.0/exe/rspec --pattern spec/\*\*\{,/\*/\*\*\}/\*_spec.rb
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/rates_store/memory.rb:103: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/rates_store/memory.rb:103: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money/formatting_rules.rb:29: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money/formatter.rb:250: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money/formatter.rb:250: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money/formatter.rb:250: warning: private attribute?
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money.rb:146: warning: method redefined; discarding old locale_backend=
/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/money-6.13.4/lib/money/money.rb:150: warning: method redefined; discarding old use_i18n=
/home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:97: warning: `<<' after local variable or literal is interpreted as binary operator
/home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:97: warning: even though it seems like here document

An error occurred while loading spec_support.
Failure/Error: require 'double_entry/validation/line_check'

SyntaxError:
  /home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:97: syntax error, unexpected <<
            log << <<~MESSAGE unless correct
                     ^
  /home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:98: syntax error, unexpected **arg, expecting keyword_end
              *********************************
                ^
  /home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:100: syntax error, unexpected **arg, expecting keyword_end
              *********************************
                ^
  /home/mark/code/opensource/double_entry/lib/double_entry/validation/line_check.rb:102: dynamic constant assignment
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
# ./lib/double_entry/validation.rb:2:in `<top (required)>'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
# ./.bundle/ruby/2.2.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
# ./lib/double_entry.rb:19:in `<top (required)>'
# ./spec/spec_support.rb:1:in `require'
# ./spec/spec_support.rb:1:in `<top (required)>'
No examples found.

Finished in 0.00004 seconds (files took 0.55766 seconds to load)
0 examples, 0 failures, 1 error occurred outside of examples

/home/mark/.rvm/rubies/ruby-2.2.10/bin/ruby -I/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-core-3.9.0/lib:/home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-support-3.9.0/lib /home/mark/code/opensource/double_entry/.bundle/ruby/2.2.0/gems/rspec-core-3.9.0/exe/rspec --pattern spec/\*\*\{,/\*/\*\*\}/\*_spec.rb failed

[orien]

This gem no longer supports Ruby 2.2. Try on Ruby 2.3 or later.

[orien]

I've added preventions in #175 so newcomers aren't surprised by this.

[dersnek]

This gem no longer supports Ruby 2.2. Try on Ruby 2.3 or later.

Tried with 2.6.3, it works, thanks!