colorize CheckEnv output

start of a test suite

.rspec

@@ -0,0 +1,2 @@
+--color
+--require spec_helper

Gemfile

@@ -0,0 +1,4 @@
+source 'https://rubygems.org'
+
+gem 'rake'
+gem 'rspec'

Gemfile.lock

@@ -0,0 +1,25 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    diff-lcs (1.2.5)
+    rake (10.4.2)
+    rspec (3.3.0)
+      rspec-core (~> 3.3.0)
+      rspec-expectations (~> 3.3.0)
+      rspec-mocks (~> 3.3.0)
+    rspec-core (3.3.2)
+      rspec-support (~> 3.3.0)
+    rspec-expectations (3.3.1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.3.0)
+    rspec-mocks (3.3.2)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.3.0)
+    rspec-support (3.3.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  rake
+  rspec

Rakefile

@@ -0,0 +1,4 @@
+require 'rspec/core/rake_task'
+RSpec::Core::RakeTask.new(:spec)
+
+task default: :spec

cli/dinghy/check_env.rb

@@ -9,9 +9,9 @@ def initialize(machine)
 
   def run
     if set?
-      puts "Your environment variables are already set correctly."
+      puts "\e[32mYour environment variables are already set correctly.\e[0m"
     else
-      puts "To connect the Docker client to the Docker daemon, please set:"
+      puts "\e[33mTo connect the Docker client to the Docker daemon, please set:\e[0m"
       print
     end
   end

cli/dinghy/docker.rb

@@ -1,18 +1,26 @@
 class Docker
   attr_reader :machine
 
-  def initialize(machine)
+  def initialize(machine, check_env = nil)
     @machine = machine
+    @check_env = check_env || CheckEnv.new(machine)
   end
 
   def system(*command)
-    set_env!
-    Kernel.system("docker", *command)
+    set_env do
+      Kernel.system("docker", *command)
+    end
   end
 
   protected
 
-  def set_env!
-    CheckEnv.new(machine).expected.each { |k,v| ENV[k] = v }
+  # Make sure to restore the old env afterwards, so that CheckEnv can validate
+  # the user's environment.
+  def set_env
+    old_env = {}
+    @check_env.expected.each { |k,v| old_env[k] = ENV[k]; ENV[k] = v }
+    yield
+  ensure
+    old_env.each { |k,v| ENV[k] = v }
   end
 end

spec/docker_spec.rb

@@ -0,0 +1,18 @@
+RSpec.describe Docker do
+  let(:machine) { double('Machine') }
+  let(:check_env) {
+    double('CheckEnv',
+      expected: { 'DOCKER_HOST' => 'realhost' }
+    )
+  }
+  subject { described_class.new(machine, check_env) }
+
+  describe '#system' do
+    it 'preserves the original environment' do
+      expect(Kernel).to receive(:system).with("docker", "ps").and_return "zero"
+      ENV['DOCKER_HOST'] = 'myhost'
+      expect(subject.system("ps")).to eq('zero')
+      expect(ENV['DOCKER_HOST']).to eq('myhost')
+    end
+  end
+end

spec/spec_helper.rb

@@ -0,0 +1,79 @@
+require(File.realpath(__FILE__)+"/../../cli/cli")
+
+# This file was generated by the `rspec --init` command. Conventionally, all
+# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
+# The generated `.rspec` file contains `--require spec_helper` which will cause
+# this file to always be loaded, without a need to explicitly require it in any
+# files.
+#
+# Given that it is always loaded, you are encouraged to keep this file as
+# light-weight as possible. Requiring heavyweight dependencies from this file
+# will add to the boot time of your test suite on EVERY test run, even for an
+# individual file that may not need all of that loaded. Instead, consider making
+# a separate helper file that requires the additional dependencies and performs
+# the additional setup, and require it from the spec files that actually need
+# it.
+#
+# The `.rspec` file also contains a few flags that are not defaults but that
+# users commonly want.
+#
+# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
+RSpec.configure do |config|
+  # rspec-expectations config goes here. You can use an alternate
+  # assertion/expectation library such as wrong or the stdlib/minitest
+  # assertions if you prefer.
+  config.expect_with :rspec do |expectations|
+    # This option will default to `true` in RSpec 4. It makes the `description`
+    # and `failure_message` of custom matchers include text for helper methods
+    # defined using `chain`, e.g.:
+    #     be_bigger_than(2).and_smaller_than(4).description
+    #     # => "be bigger than 2 and smaller than 4"
+    # ...rather than:
+    #     # => "be bigger than 2"
+    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
+  # rspec-mocks config goes here. You can use an alternate test double
+  # library (such as bogus or mocha) by changing the `mock_with` option here.
+  config.mock_with :rspec do |mocks|
+    # Prevents you from mocking or stubbing a method that does not exist on
+    # a real object. This is generally recommended, and will default to
+    # `true` in RSpec 4.
+    mocks.verify_partial_doubles = true
+  end
+
+  # The settings below are suggested to provide a good initial experience
+  # with RSpec, but feel free to customize to your heart's content.
+  # Limits the available syntax to the non-monkey patched syntax that is
+  # recommended. For more details, see:
+  #   - http://myronmars.to/n/dev-blog/2012/06/rspecs-new-expectation-syntax
+  #   - http://www.teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/
+  #   - http://myronmars.to/n/dev-blog/2014/05/notable-changes-in-rspec-3#new__config_option_to_disable_rspeccore_monkey_patching
+  config.disable_monkey_patching!
+
+  # This setting enables warnings. It's recommended, but in some cases may
+  # be too noisy due to issues in dependencies.
+  config.warnings = true
+
+  # Many RSpec users commonly either run the entire suite or an individual
+  # file, and it's useful to allow more verbose output when running an
+  # individual spec file.
+  if config.files_to_run.one?
+    # Use the documentation formatter for detailed output,
+    # unless a formatter has already been configured
+    # (e.g. via a command-line flag).
+    config.default_formatter = 'doc'
+  end
+
+  # Run specs in random order to surface order dependencies. If you find an
+  # order dependency and want to debug it, you can fix the order by providing
+  # the seed, which is printed after each run.
+  #     --seed 1234
+  config.order = :random
+
+  # Seed global randomization in this process using the `--seed` CLI option.
+  # Setting this allows you to use `--seed` to deterministically reproduce
+  # test failures related to randomization by passing the same `--seed` value
+  # as the one that triggered the failure.
+  Kernel.srand config.seed
+end