diff --git a/.travis.yml b/.travis.yml
index 90fd5471..e526021a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,7 @@ addons:
     repo_token:
       secure: "cZoMNjQKB/D7W4B7JDk9PXooy2WCDypu7R4C/Vi0DziZCU9HRwLbdt9aoH5hgHFa7Fe2rHFgflPAAP7h698ozvP0waFtPqLAj+PbEt27LbBDvW8JcvNkKXA0rj5wyTkzuc/0kD+kPB4oDXMak6gZlB9HCJDsa3kdXScQGTVuPdU="
   postgresql: "9.6"
+  firefox: "latest"
 
 before_install:
   - export DISPLAY=:99.0
@@ -17,6 +18,12 @@ before_install:
   - sleep 5
   - docker pull openhpi/co_execenv_python
   - docker pull openhpi/co_execenv_java
+  - mkdir ~/geckodriver
+  - wget -O ~/geckodriver/download.tar.gz https://github.com/mozilla/geckodriver/releases/download/v0.18.0/geckodriver-v0.18.0-linux64.tar.gz
+  - tar -xvzf ~/geckodriver/download.tar.gz -C ~/geckodriver/
+  - rm ~/geckodriver/download.tar.gz
+  - chmod +x ~/geckodriver/geckodriver
+  - export PATH=~/geckodriver/:$PATH
 
 before_script:
   - cp .rspec.travis .rspec
diff --git a/Gemfile b/Gemfile
index 076ed2aa..82dcba6c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -67,12 +67,13 @@ end
 group :test do
   gem 'autotest-rails'
   gem 'capybara'
+  gem 'capybara-selenium'
+  gem 'headless'
   gem 'codeclimate-test-reporter', require: false
   gem 'database_cleaner'
   gem 'nyan-cat-formatter'
   gem 'rake'
   gem 'rspec-autotest'
   gem 'rspec-rails'
-  gem 'selenium-webdriver'
   gem 'simplecov', require: false
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index 456aeb24..221556cc 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -85,6 +85,9 @@ GEM
       rack (>= 1.0.0)
       rack-test (>= 0.5.4)
       xpath (>= 2.0, < 4.0)
+    capybara-selenium (0.0.6)
+      capybara
+      selenium-webdriver
     carrierwave (1.2.2)
       activemodel (>= 4.0.0)
       activesupport (>= 4.0.0)
@@ -136,6 +139,7 @@ GEM
     forgery (0.7.0)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
+    headless (2.3.1)
     highline (1.7.10)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
@@ -383,6 +387,7 @@ DEPENDENCIES
   capistrano-upload-config
   capistrano3-puma
   capybara
+  capybara-selenium
   carrierwave
   codeclimate-test-reporter
   coffee-rails
@@ -395,6 +400,7 @@ DEPENDENCIES
   factory_bot_rails
   faye-websocket
   forgery
+  headless
   highline
   ims-lti (= 1.1.10)
   jbuilder
@@ -423,7 +429,6 @@ DEPENDENCIES
   rubyzip
   sass-rails
   sdoc
-  selenium-webdriver
   simplecov
   slim
   sorcery
diff --git a/deleteme.txt b/deleteme.txt
deleted file mode 100644
index e69de29b..00000000
diff --git a/spec/features/editor_spec.rb b/spec/features/editor_spec.rb
index 88e480d4..bba856e7 100644
--- a/spec/features/editor_spec.rb
+++ b/spec/features/editor_spec.rb
@@ -1,7 +1,7 @@
 require 'rails_helper'
 
 describe 'Editor', js: true do
-  let(:exercise) { FactoryBot.create(:audio_video, instructions: Forgery(:lorem_ipsum).sentence) }
+  let(:exercise) { FactoryBot.create(:audio_video, description: Forgery(:lorem_ipsum).sentence) }
   let(:user) { FactoryBot.create(:teacher) }
 
   before(:each) do
@@ -9,94 +9,74 @@ describe 'Editor', js: true do
     fill_in('email', with: user.email)
     fill_in('password', with: FactoryBot.attributes_for(:teacher)[:password])
     click_button(I18n.t('sessions.new.link'))
+    expect_any_instance_of(LtiHelper).to receive(:lti_outcome_service?).and_return(true)
     visit(implement_exercise_path(exercise))
   end
 
-  skip "is skipped" do
-    # selenium tests are currently not working locally.
-    it 'displays the exercise title' do
-      expect(page).to have_content(exercise.title)
+  it 'displays the exercise title' do
+    expect(page).to have_content(exercise.title)
+  end
+
+  it 'displays the exercise description' do
+    expect(page).to have_content(exercise.description)
+  end
+
+  it 'displays all visible files in a file tree' do
+    within('#files') do
+      exercise.files.select(&:visible).each do |file|
+        expect(page).to have_content(file.name_with_extension)
+      end
     end
   end
 
-  describe 'Instructions Tab' do
-    skip "is skipped" do
+  it "displays the main file's code" do
+    expect(page).to have_css(".frame[data-filename='#{exercise.files.detect(&:main_file?).name_with_extension}']")
+  end
 
-    before(:each) { click_link(I18n.t('activerecord.attributes.exercise.instructions')) }
-
-    it 'displays the exercise instructions' do
-      expect(page).to have_content(exercise.instructions)
+  context 'when selecting a file' do
+    before(:each) do
+      within('#files') { click_link(file.name_with_extension) }
     end
+
+    context 'when selecting a binary file' do
+      context 'when selecting an audio file' do
+        let(:file) { exercise.files.detect { |file| file.file_type.audio? } }
+
+        it 'contains an <audio> tag' do
+          expect(page).to have_css("audio[src='#{file.native_file.url}']")
+        end
+      end
+
+      context 'when selecting an image file' do
+        let(:file) { exercise.files.detect { |file| file.file_type.image? } }
+
+        it 'contains an <img> tag' do
+          expect(page).to have_css("img[src='#{file.native_file.url}']")
+        end
+      end
+
+      context 'when selecting a video file' do
+        let(:file) { exercise.files.detect { |file| file.file_type.video? } }
+
+        it 'contains a <video> tag' do
+          expect(page).to have_css("video[src='#{file.native_file.url}']")
+        end
+      end
+    end
+
+    context 'when selecting a non-binary file' do
+      let(:file) { exercise.files.detect { |file| !file.file_type.binary? && !file.hidden? } }
+
+      it "displays the file's code" do
+        expect(page).to have_css(".frame[data-filename='#{file.name_with_extension}']")
+      end
     end
   end
 
-  describe 'Workspace Tab' do
-    skip "is skipped" do
-
-    before(:each) { click_link(I18n.t('exercises.implement.workspace')) }
-
-    it 'displays all visible files in a file tree' do
-      within('#files') do
-        exercise.files.select(&:visible).each do |file|
-          expect(page).to have_content(file.name_with_extension)
-        end
-      end
-    end
-
-    it "displays the main file's code" do
-      expect(page).to have_css(".frame[data-filename='#{exercise.files.detect(&:main_file?).name_with_extension}']")
-    end
-
-    context 'when selecting a file' do
-      before(:each) do
-        within('#files') { click_link(file.name_with_extension) }
-      end
-
-      context 'when selecting a binary file' do
-        context 'when selecting an audio file' do
-          let(:file) { exercise.files.detect { |file| file.file_type.audio? } }
-
-          it 'contains an <audio> tag' do
-            expect(page).to have_css("audio[src='#{file.native_file.url}']")
-          end
-        end
-
-        context 'when selecting an image file' do
-          let(:file) { exercise.files.detect { |file| file.file_type.image? } }
-
-          it 'contains an <img> tag' do
-            expect(page).to have_css("img[src='#{file.native_file.url}']")
-          end
-        end
-
-        context 'when selecting a video file' do
-          let(:file) { exercise.files.detect { |file| file.file_type.video? } }
-
-          it 'contains a <video> tag' do
-            expect(page).to have_css("video[src='#{file.native_file.url}']")
-          end
-        end
-      end
-
-      context 'when selecting a non-binary file' do
-        let(:file) { exercise.files.detect { |file| !file.file_type.binary? } }
-
-        it "displays the file's code" do
-          expect(page).to have_css(".frame[data-filename='#{file.name_with_extension}']")
-        end
-      end
-    end
-    end
-  end
-
-  describe 'Progress Tab' do
-    skip "is skipped" do
-      before(:each) { click_link(I18n.t('exercises.implement.progress')) }
-
-      it 'does not contains a button for submitting the exercise' do
-        # pending("the button is only displayed when an correct LTI handshake to a running course happened. This is not the case in the test")
-        expect(page).not_to have_css('#submit')
-      end
-    end
+  it 'does not contains a button for submitting the exercise' do
+    click_button(I18n.t('exercises.editor.score'))
+    click_button('toggle-sidebar-output-collapsed')
+    expect(page).not_to have_css('#submit_outdated')
+    expect(page).to have_css('#submit')
   end
 end
diff --git a/spec/support/selenium.rb b/spec/support/selenium.rb
new file mode 100644
index 00000000..4aeb28de
--- /dev/null
+++ b/spec/support/selenium.rb
@@ -0,0 +1,21 @@
+require 'capybara/rspec'
+require 'selenium/webdriver'
+
+if ENV['HEADLESS_TEST'] == 'true' || ENV['USER'] == 'vagrant'
+  require 'headless'
+
+  headless = Headless.new
+  headless.start
+end
+
+Capybara.register_driver :selenium do |app|
+  profile = Selenium::WebDriver::Firefox::Profile.new
+  profile['intl.accept_languages'] = 'en'
+  capabilities = Selenium::WebDriver::Remote::Capabilities.firefox(elementScrollBehavior: 1)
+  options = Selenium::WebDriver::Firefox::Options.new
+  options.profile = profile
+  driver = Capybara::Selenium::Driver.new(app, browser: :firefox, desired_capabilities: capabilities, options: options)
+  driver.browser.manage.window.resize_to(1280, 960)
+  driver
+end
+Capybara.javascript_driver = :selenium
diff --git a/vendor/assets/images/jstree/themes/default/32px.png b/vendor/assets/images/32px.png
similarity index 100%
rename from vendor/assets/images/jstree/themes/default/32px.png
rename to vendor/assets/images/32px.png
diff --git a/vendor/assets/images/jstree/themes/default/40px.png b/vendor/assets/images/40px.png
similarity index 100%
rename from vendor/assets/images/jstree/themes/default/40px.png
rename to vendor/assets/images/40px.png
diff --git a/vendor/assets/images/jstree/themes/default/throbber.gif b/vendor/assets/images/throbber.gif
similarity index 100%
rename from vendor/assets/images/jstree/themes/default/throbber.gif
rename to vendor/assets/images/throbber.gif
diff --git a/vendor/assets/stylesheets/jstree/themes/default/style.min.css b/vendor/assets/stylesheets/style.min.css
similarity index 100%
rename from vendor/assets/stylesheets/jstree/themes/default/style.min.css
rename to vendor/assets/stylesheets/style.min.css