FIX: Redeeming an invitation fails if inviter has been destroyed.

app/models/invite_redeemer.rb

@@ -112,8 +112,10 @@ InviteRedeemer = Struct.new(:invite, :username, :name) do
   end
 
   def notify_invitee
-    invite.invited_by.notifications.create(notification_type: Notification.types[:invitee_accepted],
-                                           data: {display_username: invited_user.username}.to_json)
+    if inviter = invite.invited_by
+        inviter.notifications.create(notification_type: Notification.types[:invitee_accepted],
+                                     data: {display_username: invited_user.username}.to_json)
+    end
   end
 
   def delete_duplicate_invites

spec/models/invite_redeemer_spec.rb

@@ -2,8 +2,9 @@ require 'rails_helper'
 
 describe InviteRedeemer do
 
-  describe '#create_for_email' do
+  describe '#create_user_from_invite' do
     let(:user) { InviteRedeemer.create_user_from_invite(Fabricate(:invite, email: 'walter.white@email.com'), 'walter', 'Walter White') }
+
     it "should be created correctly" do
       expect(user.username).to eq('walter')
       expect(user.name).to eq('Walter White')
@@ -11,4 +12,32 @@ describe InviteRedeemer do
       expect(user.email).to eq('walter.white@email.com')
     end
   end
+
+  describe "#redeem" do
+    let(:invite) { Fabricate(:invite) }
+    let(:name) { 'john snow' }
+    let(:username) { 'kingofthenorth' }
+    let(:invite_redeemer) { InviteRedeemer.new(invite, username, name) }
+
+    it "should redeem the invite" do
+      inviter = invite.invited_by
+      user = invite_redeemer.redeem
+
+      expect(user.name).to eq(name)
+      expect(user.username).to eq(username)
+      expect(user.invited_by).to eq(inviter)
+      expect(inviter.notifications.count).to eq(1)
+    end
+
+    it "should not blow up if invited_by user has been removed" do
+      invite.invited_by.destroy!
+      invite.reload
+
+      user = invite_redeemer.redeem
+
+      expect(user.name).to eq(name)
+      expect(user.username).to eq(username)
+      expect(user.invited_by).to eq(nil)
+    end
+  end
 end