Remove link to reschedule if appointment group is not active

fixes LS-1915
flag=none

test plan:
- Enable the Scheduler setting for the account
- Create a published course with a teacher and a student
- Add an appointment group with at least one time slot as the teacher
- Sign up for the appointment as the student
- Delete the appointment as the teacher
- See the notification does not have a link to reschedule

Change-Id: I06a0f779a7b3690a460e9ac6403158509d7ae914
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/260076
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Nate Armstrong <narmstrong@instructure.com>
QA-Review: Nate Armstrong <narmstrong@instructure.com>
Product-Review: Eric Saupe <eric.saupe@instructure.com>

app/messages/appointment_deleted_for_user.email.erb

@@ -24,4 +24,6 @@
 <%= before_label :cancel_reason, "Reason for canceling" %>
 <%= data.cancel_reason || t(:no_reason_given, "none given") %>
 
+<% if asset.appointment_group.active? -%>
 <%= t :instructions, 'Sign up for a different time slot at the following link: %{link}', :link => content(:link) %>
+<% end %>

spec/messages/appointment_deleted_for_user.email.erb_spec.rb

@@ -60,6 +60,27 @@ describe 'appointment_deleted_for_user.email' do
     expect(@message.body).to include(user.name)
     expect(@message.body).to include(@group.name)
     expect(@message.body).to include(@course.name)
+    expect(@message.body).to include("Sign up for a different time slot at the following link")
     expect(@message.body).to include("/appointment_groups/#{@appointment_group.id}")
   end
+
+  it "should exclude reschedule instructions if appointment group isn't active" do
+    user = user_model(:name => 'bob')
+    appointment_participant_model(:participant => user)
+    @appointment_group.destroy(@teacher)
+    @event.reload
+
+    generate_message(:appointment_deleted_for_user, :email, @event,
+                     :data => {:updating_user_name => @teacher.name,
+                               :cancel_reason => "just because"})
+
+    expect(@message.subject).to include('some title')
+    expect(@message.body).to include('some title')
+    expect(@message.body).to include('just because')
+    expect(@message.body).to include(@teacher.name)
+    expect(@message.body).to include(user.name)
+    expect(@message.body).to include(@course.name)
+    expect(@message.body).not_to include("Sign up for a different time slot at the following link")
+    expect(@message.body).not_to include("/appointment_groups/#{@appointment_group.id}")
+  end
 end