OS specific tests with ruby - ruby

Question

I've the following Rakefile
require 'bundler/gem_tasks'
require 'rake/testtask'
Rake::TestTask.new do |task|
task.libs << %w(test lib)
task.pattern = 'test/**/*_test.rb'
end
task default: :test
And test are defined with minitest:
require 'test_helper'
require 'certmanager'
class CertificateTest < Minitest::Test
context 'settings' do
should 'retrieve settings' do
assert_equal 'test123', Certmanager::Settings.key_passphrase
end
end
end
Now there is also some OS specific code like FileUtils.ln_s on Linux and FileUtils.cp on Windows. This code requires different tests. In this case e.g. assert_equal filepath, File.readlink(linkpath) (Linux) vs. assert File.exist?(filepath) (windows)
What is the best practice to differentiate between OS Types?
Do I have t write the tests in a way that Linux can test windows specific code and vice versa?
Is it possible to differentiate "inline" in an test?
Is it necessary to have two different testsets and decide in the Rakefile which set needs to be executed? Is it even possible int the Rakefile?

Answer 1

In order to be able to run every test regardless of the current OS, i wrote a module TestHelper. This module contains severall methods to
pretend a windows or posix environment for the test
setup stubs for methods that are not implemented (or work in a different way) on the actual OS - currently I've only found those methods on windows
check if the actual OS is windows or not (if it is necessary to know)
In the test it is possible to simply use TestHelper.setup_windows_env or TestHelper.setup_posix_env whenever it has to be OS specific.
require 'rbconfig'
require 'fileutils'
module TestHelper
extend self
def setup_windows_env
is_windows?
RbConfig::CONFIG.stubs(:[]).with('host_os').returns('windows')
ENV.stubs(:[]).with('OS').returns('Windows_NT')
end
def setup_stubs_for_windows_in_posix_env
class << FileUtils
def ln_s(src, dest, options = {})
File.open(dest, 'w') { |file| file.write src }
return 0
end
end
class << File
def readlink(file_name)
return File.read(file_name)
end
end
end
def setup_posix_env
setup_stubs_for_windows_in_posix_env if is_windows?
RbConfig::CONFIG.stubs(:[]).with('host_os').returns('darwin')
ENV.stubs(:[]).with('OS').returns('OSX')
end
def is_windows?
#is_windows ||= ApplicationToTest::Util::OS.is_windows?
end
end
For completeness ApplicationToTest::Util::OS.is_windows?:
require 'rbconfig'
module ApplicationToTest
module Util
module OS
def self.is_windows?
begin
env_os = ENV['OS']
rescue NameError
return false
end
if RbConfig::CONFIG['host_os'] =~ /^mingw2$|^mingw$|^mswin$|^windows$/
true
elsif env_os == 'Windows_NT'
true
else
false
end
end
end
end
end