[Multiple issue asignees] fix update_cache_counts for issues and specs for that[ci skip]

app/models/issue.rb

@@ -136,14 +136,6 @@ class Issue < ActiveRecord::Base
               "id DESC")
   end
 
-  def update_assignee_cache_counts
-    return true # TODO implement it properly
-    # make sure we flush the cache for both the old *and* new assignees(if they exist)
-    previous_assignee = User.find_by_id(assignee_id_was) if assignee_id_was
-    previous_assignee&.update_cache_counts
-    assignee&.update_cache_counts
-  end
-
   # Returns a Hash of attributes to be used for Twitter card metadata
   def card_attributes
     {

app/models/issue_assignee.rb

 class IssueAssignee < ActiveRecord::Base
-    belongs_to :issue
-    belongs_to :assignee, class_name: "User", foreign_key: :user_id
+  belongs_to :issue
+  belongs_to :assignee, class_name: "User", foreign_key: :user_id
+
+  after_create :update_assignee_cache_counts
+  after_destroy :update_assignee_cache_counts
+
+  def update_assignee_cache_counts
+    assignee&.update_cache_counts
+  end
 end

app/models/merge_request.rb

@@ -210,7 +210,7 @@ class MergeRequest < ActiveRecord::Base
 
   # This method is needed for compatibility with issues to not mess view and other code
   def assignees
-    assignee ? [assignee] : []
+    Array(assignee)
   end
 
   def assignee_or_author?(user)

spec/models/concerns/issuable_spec.rb

@@ -58,12 +58,12 @@ describe Issue, "Issuable" do
   end
 
   describe "before_save" do
-    describe "#update_cache_counts" do
+    describe "#update_cache_counts when an issue is reassigned" do
       context "when previous assignee exists" do
         before do
           assignee = create(:user)
           issue.project.team << [assignee, :developer]
-          issue.update(assignee: assignee)
+          issue.assignees << assignee
         end
 
         it "updates cache counts for new assignee" do
@@ -71,26 +71,65 @@ describe Issue, "Issuable" do
 
           expect(user).to receive(:update_cache_counts)
 
-          issue.update(assignee: user)
+          issue.assignees << user
         end
 
         it "updates cache counts for previous assignee" do
-          old_assignee = issue.assignee
+          old_assignee = issue.assignees.first
+
+          expect_any_instance_of(User).to receive(:update_cache_counts)
+
+          issue.assignees.destroy_all
+        end
+      end
+
+      context "when previous assignee does not exist" do
+        before{ issue.assignees = [] }
+
+        it "updates cache count for the new assignee" do
+          expect_any_instance_of(User).to receive(:update_cache_counts)
+
+          issue.assignees << user
+        end
+      end
+    end
+
+    describe "#update_cache_counts when a merge request is reassigned" do
+      let(:project) { create :project }
+      let(:merge_request) { create(:merge_request, source_project: project, target_project: project) }
+
+      context "when previous assignee exists" do
+        before do
+          assignee = create(:user)
+          project.team << [assignee, :developer]
+          merge_request.update(assignee: assignee)
+        end
+
+        it "updates cache counts for new assignee" do
+          user = create(:user)
+
+          expect(user).to receive(:update_cache_counts)
+
+          merge_request.update(assignee: user)
+        end
+
+        it "updates cache counts for previous assignee" do
+          old_assignee = merge_request.assignee
           allow(User).to receive(:find_by_id).with(old_assignee.id).and_return(old_assignee)
 
           expect(old_assignee).to receive(:update_cache_counts)
 
-          issue.update(assignee: nil)
+          merge_request.update(assignee: nil)
         end
       end
 
       context "when previous assignee does not exist" do
-        before{ issue.update(assignee: nil) }
+        before { merge_request.update(assignee: nil) }
 
         it "updates cache count for the new assignee" do
           expect_any_instance_of(User).to receive(:update_cache_counts)
 
-          issue.update(assignee: user)
+          merge_request.update(assignee: user)
         end
       end
     end