Fix cancel button in issue template update warning

This commit also does the following:

- Adds an extra spec to validate close and
dismiss buttons
- Adds an extra assertion to validate template
warning element not found on the DOM
- Fixes resetting template content for new issues
- Fixes content saving to localStorage when
template changed

app/assets/javascripts/blob/template_selector.js

@@ -83,6 +83,7 @@ export default class TemplateSelector {
 
     if (this.editor instanceof $) {
       this.editor.get(0).dispatchEvent(this.autosizeUpdateEvent);
+      this.editor.trigger('input');
     }
   }
 

app/assets/javascripts/templates/issuable_template_selector.js

@@ -31,7 +31,8 @@ export default class IssuableTemplateSelector extends TemplateSelector {
     });
 
     this.templateWarningEl.find('.js-close-btn').on('click', () => {
-      if (this.previousSelectedIndex) {
+      // Explicitly check against 0 value
+      if (this.previousSelectedIndex !== undefined) {
         this.dropdown.data('glDropdown').selectRowAtIndex(this.previousSelectedIndex);
       } else {
         this.reset();
@@ -109,6 +110,7 @@ export default class IssuableTemplateSelector extends TemplateSelector {
     } else {
       this.setEditorContent(this.currentTemplate, { skipFocus: false });
     }
+
     return;
   }
 }

app/views/shared/form_elements/_apply_template_warning.html.haml

@@ -2,7 +2,7 @@
   .offset-sm-2.col-sm-10
 
     .warning_message.mb-0{ role: 'alert' }
-      %btn.js-close-btn.close{ type: "button", "aria-hidden": true, "aria-label": _("Close") }
+      %btn.js-close-btn.js-dismiss-btn.close{ type: "button", "aria-hidden": true, "aria-label": _("Close") }
         = sprite_icon("close")
 
       %p
@@ -10,5 +10,5 @@
 
       %button.js-override-template.btn.btn-warning.mr-2{ type: 'button' }
         = _("Apply template")
-      %button.js-cancel-btn.btn.btn-inverted{ type: 'button' }
+      %button.js-close-btn.js-cancel-btn.btn.btn-inverted{ type: 'button' }
         = _("Cancel")

spec/features/projects/issuable_templates_spec.rb

@@ -131,8 +131,15 @@ describe 'issuable templates', :js do
       end
 
       it 'user selects "bug" template, then updates description, then selects "feature-proposal" template, then cancels template change' do
-        page.find('.js-template-warning .js-cancel-btn').click
+        page.find('.js-template-warning .js-close-btn.js-cancel-btn').click
         expect(find('textarea')['value']).to eq(updated_description)
+        expect(page).not_to have_content template_override_warning
+      end
+
+      it 'user selects "bug" template, then updates description, then selects "feature-proposal" template, then dismiss the template warning' do
+        page.find('.js-template-warning .js-close-btn.js-dismiss-btn').click
+        expect(find('textarea')['value']).to eq(updated_description)
+        expect(page).not_to have_content template_override_warning
       end
 
       it 'user selects "bug" template, then updates description, then selects "feature-proposal" template, then applies template change' do