Add basic test that Monaco is hooked up

Author: shepmaster

tests/spec/features/editor_types_spec.rb

@@ -25,4 +25,29 @@ def simple_editor_code
     }
     EOF
   end
+
+  scenario "using the Monaco editor" do
+    in_config_menu { select("monaco") }
+
+    editor = page.find('.monaco-editor')
+
+    # Click on the last line as that will replace the entire content
+    editor.find('.view-line:last-child').click
+    t = editor.find('textarea', visible: false)
+    t.set(monaco_editor_code, clear: :backspace)
+
+    click_on("Run")
+
+    within(:output, :stdout) do
+      expect(page).to have_content 'Monaco editor'
+    end
+  end
+
+  # Missing indentation and closing curly braces as those are auto-inserted
+  def monaco_editor_code
+    <<~EOF
+    fn main() {
+    println!("Using the Monaco editor");
+    EOF
+  end
 end