setting up test infrastructure

.gitignore

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+vendor/
+.bundle/

.rspec

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+--color
+--require spec_helper

Gemfile

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+source "https://rubygems.org"
+
+group :development do
+  gem "docker-api"
+  gem "rspec"
+end

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    diff-lcs (1.2.5)
+    docker-api (1.21.4)
+      excon (>= 0.38.0)
+      json
+    excon (0.45.3)
+    json (1.8.2)
+    rspec (3.2.0)
+      rspec-core (~> 3.2.0)
+      rspec-expectations (~> 3.2.0)
+      rspec-mocks (~> 3.2.0)
+    rspec-core (3.2.3)
+      rspec-support (~> 3.2.0)
+    rspec-expectations (3.2.1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.2.0)
+    rspec-mocks (3.2.1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.2.0)
+    rspec-support (3.2.2)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  docker-api
+  rspec
+
+BUNDLED WITH
+   1.10.2

spec/fixtures/hello_world/Dockerfile

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+FROM heroku/cedar:14
+
+RUN useradd -d /app -m app
+USER app
+WORKDIR /app
+
+ENV HOME /app
+ENV PORT 3000
+
+RUN mkdir -p /app
+COPY . /app/
+
+RUN /app/buildpack/bin/compile /app
+
+EXPOSE 3000
+CMD /app/bin/boot

spec/fixtures/hello_world/public_html/index.html

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+Hello World

spec/fixtures/hello_world/static.json

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+{}

spec/simple_spec.rb

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+require_relative "spec_helper"
+require_relative "support/buildpack_runner"
+
+describe "Simple" do
+  let(:bp) { BuildpackRunner.new("hello_world") }
+
+  after do
+    bp.destroy
+  end
+
+  it "should serve out of public_html by default" do
+    response = bp.get("/")
+    expect(response.code).to eq("200")
+    expect(response.body.chomp).to eq("Hello World")
+  end
+end

spec/spec_helper.rb

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+# 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.
+=begin
+  # These two settings work together to allow you to limit a spec run
+  # to individual examples or groups you care about by tagging them with
+  # `:focus` metadata. When nothing is tagged with `:focus`, all examples
+  # get run.
+  config.filter_run :focus
+  config.run_all_when_everything_filtered = true
+
+  # 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://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
+
+  # Print the 10 slowest examples and example groups at the
+  # end of the spec run, to help surface which specs are running
+  # particularly slow.
+  config.profile_examples = 10
+
+  # 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
+end

spec/support/buildpack_runner.rb

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+require "uri"
+require "net/http"
+require "fileutils"
+require "json"
+require "docker"
+require_relative "path_helper"
+
+class BuildpackRunner
+  include PathHelper
+
+  HOST_PORT      = "3000"
+  HOST_IP        = "127.0.0.1"
+  CONTAINER_PORT = "3000"
+
+  def initialize(fixture, debug = false)
+    @debug     = debug
+    @image     = build_image(fixture)
+    puts @image.id if @debug
+    @container = Docker::Container.create(
+      'Image'      => @image.id,
+      'HostConfig' => {
+        'PortBindings' => {
+          "#{CONTAINER_PORT}/tcp" => [{
+            "HostIp" => HOST_IP,
+            "HostPort": HOST_PORT, 
+          }]
+        }
+      }
+    )
+  end
+
+  def run
+    #@container.tap(&:start).attach { |stream, chunk| puts "#{stream}: #{chunk}" }
+    @container.start
+    sleep(1)
+    yield(@container)
+    @container.stop
+  end
+
+  def get(path)
+    response = nil
+    run do
+      uri      = URI("http://#{HOST_IP}:#{HOST_PORT}/#{path}")
+      response = Net::HTTP.get_response(uri)
+    end
+
+    return response
+  end
+
+  def destroy
+    unless @debug
+      @container.delete(force: true)
+      @image.remove(force: true)
+    end
+  end
+
+  private
+  def build_image(fixture)
+    image = nil
+
+    Dir.mktmpdir do |tmpdir|
+      fixture_path = fixtures_path(fixture)
+      dest_bp_dir  = Pathname.new(File.join(tmpdir, "buildpack"))
+      print_output =
+        if @debug
+          -> (chunk) {
+            json = JSON.parse(chunk)
+            puts json["stream"]
+          }
+        else
+          -> (chunk) { nil }
+        end
+
+      FileUtils.mkdir_p(dest_bp_dir)
+      FileUtils.cp_r(buildpack_path("bin"), dest_bp_dir)
+      FileUtils.cp_r(buildpack_path("scripts"), dest_bp_dir)
+      FileUtils.cp_r(Dir.glob(fixture_path + "*"), tmpdir)
+      image = Docker::Image.build_from_dir(tmpdir, &print_output)
+    end
+
+    image
+  end
+end

spec/support/path_helper.rb

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+module PathHelper
+  def fixtures_path(*path)
+    __build_path("../fixtures", *path)
+  end
+
+  def buildpack_path(*path)
+    __build_path("../../", *path)
+  end
+
+  private
+  def __build_path(name, *path)
+    Pathname.new(File.join(File.dirname(__FILE__), name, *path))
+  end
+end