Use system specs instead of feature specs

We get rid of database cleaner, and JavaScript tests are faster because
between tests we now rollback transactions instead of truncating the
database.

spec/system/admin/site_customization/documents_spec.rb

@@ -0,0 +1,88 @@
+require "rails_helper"
+
+describe "Documents" do
+  before do
+    admin = create(:administrator)
+    login_as(admin.user)
+  end
+
+  scenario "Navigation", :js do
+    visit admin_root_path
+
+    within("#side_menu") do
+      click_link "Site content"
+      click_link "Custom documents"
+    end
+
+    expect(page).to have_link "Add new document",
+                              href: new_admin_site_customization_document_path
+  end
+
+  scenario "Index" do
+    3.times { create(:document, :admin) }
+    1.times { create(:document) }
+
+    visit admin_site_customization_documents_path
+
+    expect(page).to have_content "There are 3 documents"
+
+    document = Document.first
+    expect(page).to have_link document.title, href: document.attachment.url
+  end
+
+  scenario "Index (empty)" do
+    visit admin_site_customization_documents_path
+
+    expect(page).to have_content "There are no documents."
+  end
+
+  scenario "Index (pagination)" do
+    per_page = 3
+    allow(Document).to receive(:default_per_page).and_return(per_page)
+    (per_page + 2).times { create(:document, :admin) }
+
+    visit admin_site_customization_documents_path
+
+    expect(page).to have_selector("#documents .document", count: per_page)
+
+    within("ul.pagination") do
+      expect(page).to have_content("1")
+      expect(page).to have_link("2", href: admin_site_customization_documents_path(page: 2))
+      expect(page).not_to have_content("3")
+      click_link "Next", exact: false
+    end
+
+    expect(page).to have_selector("#documents .document", count: 2)
+  end
+
+  scenario "Create" do
+    visit new_admin_site_customization_document_path
+
+    attach_file("document_attachment", Rails.root + "spec/fixtures/files/logo.pdf")
+    click_button "Upload"
+
+    expect(page).to have_content "Document uploaded succesfully"
+    expect(page).to have_link "logo.pdf", href: Document.last.attachment.url
+  end
+
+  scenario "Errors on create" do
+    visit new_admin_site_customization_document_path
+
+    click_button "Upload"
+
+    expect(page).to have_content "Invalid document"
+  end
+
+  scenario "Destroy", :js do
+    document = create(:document, :admin)
+
+    visit admin_site_customization_documents_path
+
+    within("#document_#{document.id}") do
+      accept_confirm { click_link "Delete" }
+    end
+
+    expect(page).to have_content "Document deleted succesfully"
+    expect(page).not_to have_content document.title
+  end
+end