some auto follow/unfollow fixes for sharding

also a fix for UserFollow#check_auto_follow_collections, which was kind
of only working by accident across shards.

test plan: have a user join a group in another shard, and see that they
auto-follow collections in the group. have them leave the group, and see
that they auto-unfollow private collections in the group.

Change-Id: Ic1efd9e527d14d4a21c0db828ba228dd0b3753e8
Reviewed-on: https://gerrit.instructure.com/11719
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>

app/models/group.rb

@@ -134,15 +134,18 @@ class Group < ActiveRecord::Base
   end
 
   def membership_for_user(user)
-    self.group_memberships.find_by_user_id(user && user.id)
+    return nil unless user.present?
+    self.shard.activate { self.group_memberships.find_by_user_id(user.id) }
   end
 
   def has_member?(user)
-    self.participating_group_memberships.find_by_user_id(user && user.id)
+    return nil unless user.present?
+    self.shard.activate { self.participating_group_memberships.find_by_user_id(user.id) }
   end
 
   def has_moderator?(user)
-    self.participating_group_memberships.moderators.find_by_user_id(user && user.id)
+    return nil unless user.present?
+    self.shard.activate { self.participating_group_memberships.moderators.find_by_user_id(user.id) }
   end
 
   def should_add_creator?

app/models/group_membership.rb

@@ -112,7 +112,7 @@ class GroupMembership < ActiveRecord::Base
     if (self.id_changed? || self.workflow_state_changed?) && self.active?
       UserFollow.create_follow(self.user, self.group)
     elsif self.destroyed? || (self.workflow_state_changed? && self.deleted?)
-      user_follow = self.user.user_follows.find(:first, :conditions => { :followed_item_id => self.group_id, :followed_item_type => 'Group' })
+      user_follow = self.user.shard.activate { self.user.user_follows.find(:first, :conditions => { :followed_item_id => self.group_id, :followed_item_type => 'Group' }) }
       user_follow.try(:destroy)
     end
   end

app/models/user_follow.rb

@@ -68,14 +68,25 @@ class UserFollow < ActiveRecord::Base
   #
   # this way both associations work as expected
   set_shard_override do |record|
-    record.following_user.shard unless record.complementary_record
+    record.following_user.shard unless record.complementary_record?
   end
 
   after_create :create_complementary_record
-  attr_accessor :complementary_record
+  attr_writer :complementary_record
+
+  # returns true if the following user isn't on the same shard as the followed
+  # item, and this UserFollow is the secondary copy that's on the followed
+  # item's shard
+  def complementary_record?
+    if new_record?
+      @complementary_record
+    else
+      self.shard != following_user.shard
+    end
+  end
 
   def create_complementary_record
-    if !complementary_record && followed_item.shard != following_user.shard
+    if !complementary_record? && followed_item.shard != following_user.shard
       followed_item.shard.activate do
         UserFollow.create_follow(following_user, followed_item, true)
       end
@@ -85,10 +96,10 @@ class UserFollow < ActiveRecord::Base
 
   after_destroy :destroy_complementary_record
   def destroy_complementary_record
-    complementary_record.try(:destroy)
+    find_complementary_record.try(:destroy)
   end
 
-  def complementary_record
+  def find_complementary_record
     return nil if followed_item.shard == following_user.shard
     if self.shard == followed_item.shard
       finding_shard = following_user.shard
@@ -110,7 +121,7 @@ class UserFollow < ActiveRecord::Base
   # when a user follows a group or other user, they auto-follow all existing
   # collections in that context as well
   def check_auto_follow_collections
-    return true if complementary_record
+    return true if self.complementary_record?
     case followed_item
     when User, Group
       if !followed_item.collections.empty?
@@ -133,7 +144,7 @@ class UserFollow < ActiveRecord::Base
   # when a user leaves a group, they auto-unfollow all private collections in
   # that group
   def check_auto_unfollow_collections
-    return true if complementary_record
+    return true if self.complementary_record?
     case followed_item
     when Group
       if !followed_item.collections.empty?

spec/models/user_follow_spec.rb

@@ -68,6 +68,21 @@ describe "UserFollow" do
       expect { @uf.reload }.to raise_error(ActiveRecord::RecordNotFound)
     end
 
+    it "should unfollow private collections on group unfollow" do
+      @shard1.activate do
+        @group = Group.create!(:group_category => GroupCategory.communities_for(Account.default), :is_public => true, :join_level => 'parent_context_auto_join')
+        @coll = @group.collections.create!(:name => 'col1', :visibility => 'private')
+      end
+      @membership = @group.add_user(@user1)
+      @follow = @group.following_user_follows.first
+      @follow.following_user.should == @user1
+      run_jobs
+      @coll.reload.following_user_follows.map(&:following_user).should == [@user1]
+      @membership.destroy
+      run_jobs
+      @coll.reload.following_user_follows.map(&:following_user).should == []
+    end
+
     def verify
       yield
       @shard1.activate { yield }