Add failing test for administering newsletters

Author: rossta

spec/system/admin/newsletter_spec.rb

@@ -0,0 +1,29 @@
+require "rails_helper"
+
+RSpec.describe "Admin for Newsletters", type: :system do
+  it "create and send a newsletter" do
+    login_as_admin
+
+    visit admin_newsletters_path
+
+    click_on "New Newsletter"
+
+    fill_in "Title", with: "Welcome to Joy of Rails!"
+
+    fill_in "Body", with: <<~MARKDOWN
+      # Welcome to the newsletter
+
+      This is the first newsletter.
+    MARKDOWN
+
+    click_button "Save Newsletter"
+
+    expect(page).to have_content("Newsletter was successfully created.")
+
+    expect(page).to have_content("Welcome to Joy of Rails!")
+
+    click_on "Send Test"
+
+    click_on "Send Live"
+  end
+end