Allow mentors to update their comments on applications

app/views/mentors/applications/_comment.html.slim

@@ -1,5 +1,12 @@
+ruby:
+  comment_path = if comment.persisted? then
+                    mentors_comment_path(comment)
+                  else
+                    mentors_comments_path
+                  end
+
 hr(id="#{dom_id comment}")
-= simple_form_for comment, url: mentors_comments_path do |f|
+= simple_form_for comment, url: comment_path do |f|
   .form-inputs.clearfix
     = f.input :commentable_id, as: :hidden, value: comment.commentable_id
     = f.input :text, as: :text, label: 'My Comment', input_html: { rows: 5 }, hint: 'This is a place for you to take notes for yourself about this application. Your comment is only visible to yourself as well as the selection committee and you can update and remove it as you like.'

spec/features/mentors/applications/show_spec.rb

@@ -32,6 +32,33 @@
     expect(page).to have_button 'Create Comment'
   end
 
+  it 'lets the mentor create a comment' do
+    login_as user
+
+    visit mentors_application_path(application)
+
+    fill_in 'My Comment', with: 'Test Comment'
+    click_button 'Create Comment'
+
+    expect(page).to have_content 'Test Comment'
+  end
+
+  it 'lets the mentor update a comment' do
+    login_as user
+
+    visit mentors_application_path(application)
+
+    fill_in 'My Comment', with: 'Test Comment'
+    click_button 'Create Comment'
+
+    expect(page).to have_content 'Test Comment'
+
+    fill_in 'My Comment', with: 'Updated Comment'
+    click_button 'Update Comment'
+
+    expect(page).to have_content 'Updated Comment'
+  end
+
   context 'when the project is 2nd choice' do
     let(:application) { create(:application, :in_current_season, :for_project, project2: project, team: team) }