```ruby
# make sure these tests are indeed running inside opal, not any other
# ruby engine.
#unless RUBY_ENGINE =~ /opal/
#  abort <<-EOS
#Opal Tests
#==========
#
#These tests MUST be run inside opal, not `#{RUBY_ENGINE}' engine
#
#To run Array#first tests, for example:
#
#    opal spec/core/array/first_spec.rb
#
#EOS
#end

require 'opal/spec/autorun'

##
# Spec runner - if in browser, and spec_helper.rb is the main file then
# just run the spec files immediately.
if $0 == __FILE__
  Dir['runtime/spec/**/*.rb'].each { |spec| require spec }
end

```

Make sure runtime/spec tests are running inside opal, not ruby
user
```ruby
# make sure these tests are indeed running inside opal, not any other
# ruby engine.
unless RUBY_ENGINE =~ /opal/
  abort <<-EOS
Opal Tests
==========

These tests MUST be run inside opal, not `#{RUBY_ENGINE}' engine

To run Array#first tests, for example:

    opal spec/core/array/first_spec.rb

EOS
end

require 'opal/spec/autorun'

# Spec runner - if in browser, and spec_helper.rb is the main file then
# just run the spec files immediately.
if $0 == __FILE__
  Dir['runtime/spec/**/*.rb'].each { |spec| require spec }
end
```
assistant