Add integration tests with capybara (#1707)

* Add integration tests with capybara
* Add Rake task for running integration tests
* Don't include integration in default test task

test/integration/test_js_errors.rb

@@ -0,0 +1,49 @@
+require File.expand_path(File.join(File.dirname(__FILE__), '..', 'helper'))
+require 'selenium-webdriver'
+require 'capybara/dsl'
+
+Capybara.default_driver = ::CAPYBARA_DRIVER
+Capybara.server = :webrick
+
+def console_log(page, level = :severe)
+  page.driver.browser.logs.get(:browser).select{|log| log.level == level.to_s.upcase }
+end
+
+def expected_errors
+  Regexp.union([
+    %r{Refused to apply style from 'http:.*/gollum/create/custom.css'}
+  ])
+end
+
+def assert_only_expected_errors(log)
+  assert_equal [], log.reject {|err| err.message.match?(expected_errors) }
+end
+
+context 'Frontend with mathjax' do
+  include Capybara::DSL
+  
+  setup do
+    @path = cloned_testpath("examples/lotr.git")
+    @wiki = Gollum::Wiki.new(@path)
+    Precious::App.set(:gollum_path, @path)
+    Precious::App.set(:wiki_options, {mathjax: true})
+    Capybara.app = Precious::App
+  end
+  
+  test 'no unexpected errors on /' do
+    visit '/'
+    log = console_log(page)
+    assert_only_expected_errors(log)
+  end
+  
+  test 'no unexpected errors on /create/' do
+    visit '/create/Foobar'
+    log = console_log(page)
+    assert_only_expected_errors(log)
+  end
+  
+  teardown do
+    Capybara.reset_sessions!
+    Capybara.use_default_driver
+  end
+end