Test the help panel's "Emoji" section

This test is passing. I wrote it so I can safely change this panel in a
subsequent commit.

test/integration/test_editor.rb

@@ -0,0 +1,52 @@
+require_relative "../capybara_helper"
+
+context "editor interface" 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, {}
+
+    Capybara.app = Precious::App
+  end
+
+  teardown do
+    @path = nil
+    @wiki = nil
+
+    Capybara.reset_sessions!
+    Capybara.use_default_driver
+  end
+
+  test "editor renders help panel" do
+    visit "/create/new-article"
+
+    in_editor_toolbar do
+      click_on "Help"
+    end
+
+    help_widget = find "#gollum-editor-help"
+
+    within help_widget do
+      click_on "Miscellaneous"
+      click_on "Emoji"
+
+      assert_includes page.text,
+        "See the EmojiOne demo for all available emoji. To include one, " \
+        "wrap the emoji name in colons and use underscores instead of "   \
+        "spaces (e.g. :heart: or :point_up:)."
+    end
+
+  end
+
+  def in_editor_toolbar &block
+    return unless block_given?
+
+    within "#gollum-editor-function-bar" do
+      yield
+    end
+  end
+end