Question

Is there a way to change the RUBY_PLATFORM constant so that I can test the following method?

def determine_os
  case RUBY_PLATFORM
    when /darwin/ then :mac
    when /linux/ then :linux
    else raise InvalidOSError
  end
end

Answer 1

RUBY_PLATFORM shouldn’t be used to determine operating system. Use the appropriate item within the hash RbConfig instead.

Also, if you want to make it more easily tested, you could do

def determine_os(os_string)
  case os_string
    when /darwin/ then :mac
    when /linux/ then :linux
    else raise InvalidOSError
  end
end

and you could do determine_os("darwin") for your test.