Add tests for adder toolbar callbacks in Guest

Add tests for the main code paths in `Guest` that call `createAnnotation`.

src/annotator/guest.js

@@ -122,13 +122,13 @@ export default class Guest extends Delegator {
     this.element.appendChild(this.adderToolbar);
 
     this.adderCtrl = new Adder(this.adderToolbar, {
-      onAnnotate: () => {
-        this.createAnnotation();
+      onAnnotate: async () => {
+        await this.createAnnotation();
         /** @type {Selection} */ (document.getSelection()).removeAllRanges();
       },
-      onHighlight: () => {
+      onHighlight: async () => {
         this.setVisibleHighlights(true);
-        this.createHighlight();
+        await this.createHighlight();
         /** @type {Selection} */ (document.getSelection()).removeAllRanges();
       },
       onShowAnnotations: anns => {
@@ -572,6 +572,8 @@ export default class Guest extends Delegator {
    *
    * This flag indicates that the sidebar should save the new annotation
    * automatically and not show a form for the user to enter a comment about it.
+   *
+   * @return {Promise<AnnotationData>}
    */
   createHighlight() {
     return this.createAnnotation({ $highlight: true });

src/annotator/test/guest-test.js

@@ -570,8 +570,28 @@ describe('Guest', () => {
     });
   });
 
-  describe('when adder toolbar buttons are clicked', () =>
-    // TODO - Add tests for "Annotate" and "Highlight" buttons.
+  describe('when adder toolbar buttons are clicked', () => {
+    // nb. Detailed tests for properties of new annotations are in the
+    // `createAnnotation` tests.
+    it('creates a new annotation if "Annotate" is clicked', async () => {
+      const guest = createGuest();
+      const callback = sinon.stub();
+      guest.subscribe('beforeAnnotationCreated', callback);
+
+      await FakeAdder.instance.options.onAnnotate();
+
+      assert.called(callback);
+    });
+
+    it('creates a new highlight if "Highlight" is clicked', async () => {
+      const guest = createGuest();
+      const callback = sinon.stub();
+      guest.subscribe('beforeAnnotationCreated', callback);
+
+      await FakeAdder.instance.options.onHighlight();
+
+      assert.calledWith(callback, sinon.match({ $highlight: true }));
+    });
 
     it('shows annotations if "Show" is clicked', () => {
       createGuest();
@@ -580,7 +600,8 @@ describe('Guest', () => {
 
       assert.calledWith(fakeCrossFrame.call, 'openSidebar');
       assert.calledWith(fakeCrossFrame.call, 'showAnnotations', ['ann1']);
-    }));
+    });
+  });
 
   describe('#getDocumentInfo', () => {
     let guest;