Ensure that clicking on the MIR source links highlights the text

Author: shepmaster

tests/spec/features/highlighting_mir_output_spec.rb

@@ -0,0 +1,34 @@
+require 'spec_helper'
+require 'support/editor'
+require 'support/playground_actions'
+
+RSpec.feature "Highlighting MIR output", type: :feature, js: true do
+  include PlaygroundActions
+
+  before do
+    visit '/'
+    editor.set(code)
+    in_build_menu { click_on("MIR") }
+  end
+
+  scenario "error locations are links" do
+    within('.output-mir') do
+      click_link('src/main.rs:4:14: 4:19', match: :first)
+    end
+    expect(editor).to have_highlighted_text('a + b')
+  end
+
+  def editor
+    Editor.new(page)
+  end
+
+  def code
+    <<~EOF
+    fn main() {
+        let a = 1;
+        let b = 2;
+        let _c = a + b;
+    }
+    EOF
+  end
+end

tests/spec/support/editor.rb

@@ -15,4 +15,17 @@ def set(text)
   def has_line?(text)
     page.has_css? '.ace_line', text: text
   end
+
+  def has_highlighted_text?(text)
+    page.within('.editor .ace_text-input', visible: :any) do
+      selected = page.evaluate_script <<~JS
+        (() => {
+          const editor = document.querySelector('.ace_editor').env.editor;
+          return editor.getSelectedText();
+        })()
+      JS
+
+      selected == text
+    end
+  end
 end