2 files changed, 163 insertions, 4 deletions
diff --git a/spec/models/concerns/deprecated_assignee_spec.rb b/spec/models/concerns/deprecated_assignee_spec.rb
new file mode 100644
index 00000000000..e394de0aa34
--- /dev/null
+++ b/spec/models/concerns/deprecated_assignee_spec.rb
@@ -0,0 +1,160 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DeprecatedAssignee do
+  let(:user) { create(:user) }
+
+  describe '#assignee_id=' do
+    it 'creates the merge_request_assignees relation' do
+      merge_request = create(:merge_request, assignee_id: user.id)
+
+      merge_request.reload
+
+      expect(merge_request.merge_request_assignees.count).to eq(1)
+    end
+
+    it 'nullifies the assignee_id column' do
+      merge_request = create(:merge_request, assignee_id: user.id)
+
+      merge_request.reload
+
+      expect(merge_request.read_attribute(:assignee_id)).to be_nil
+    end
+
+    context 'when relation already exists' do
+      it 'overwrites existing assignees' do
+        other_user = create(:user)
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.merge_request_assignees.create!(user_id: user.id)
+        merge_request.merge_request_assignees.create!(user_id: other_user.id)
+
+        expect { merge_request.update!(assignee_id: other_user.id) }
+          .to change { merge_request.reload.merge_request_assignees.count }
+          .from(2).to(1)
+      end
+    end
+  end
+
+  describe '#assignee=' do
+    it 'creates the merge_request_assignees relation' do
+      merge_request = create(:merge_request, assignee: user)
+
+      merge_request.reload
+
+      expect(merge_request.merge_request_assignees.count).to eq(1)
+    end
+
+    it 'nullifies the assignee_id column' do
+      merge_request = create(:merge_request, assignee: user)
+
+      merge_request.reload
+
+      expect(merge_request.read_attribute(:assignee_id)).to be_nil
+    end
+
+    context 'when relation already exists' do
+      it 'overwrites existing assignees' do
+        other_user = create(:user)
+        merge_request = create(:merge_request, assignee: nil)
+        merge_request.merge_request_assignees.create!(user_id: user.id)
+        merge_request.merge_request_assignees.create!(user_id: other_user.id)
+
+        expect { merge_request.update!(assignee: other_user) }
+          .to change { merge_request.reload.merge_request_assignees.count }
+          .from(2).to(1)
+      end
+    end
+  end
+
+  describe '#assignee_id' do
+    it 'returns the first assignee ID' do
+      other_user = create(:user)
+      merge_request = create(:merge_request, assignees: [user, other_user])
+
+      merge_request.reload
+
+      expect(merge_request.assignee_id).to eq(merge_request.assignee_ids.first)
+    end
+  end
+
+  describe '#assignees' do
+    context 'when assignee_id exists and there is no relation' do
+      it 'creates the relation' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignees }.to change { merge_request.merge_request_assignees.count }.from(0).to(1)
+      end
+
+      it 'nullifies the assignee_id' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignees }
+          .to change { merge_request.read_attribute(:assignee_id) }
+          .from(user.id).to(nil)
+      end
+    end
+
+    context 'when DB is read-only' do
+      before do
+        allow(Gitlab::Database).to receive(:read_only?) { true }
+      end
+
+      it 'returns a users relation' do
+        merge_request = create(:merge_request, assignee_id: user.id)
+
+        expect(merge_request.assignees).to be_a(ActiveRecord::Relation)
+        expect(merge_request.assignees).to eq([user])
+      end
+
+      it 'returns an empty relation if no assignee_id is set' do
+        merge_request = create(:merge_request, assignee_id: nil)
+
+        expect(merge_request.assignees).to be_a(ActiveRecord::Relation)
+        expect(merge_request.assignees).to eq([])
+      end
+    end
+  end
+
+  describe '#assignee_ids' do
+    context 'when assignee_id exists and there is no relation' do
+      it 'creates the relation' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignee_ids }.to change { merge_request.merge_request_assignees.count }.from(0).to(1)
+      end
+
+      it 'nullifies the assignee_id' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignee_ids }
+          .to change { merge_request.read_attribute(:assignee_id) }
+          .from(user.id).to(nil)
+      end
+    end
+
+    context 'when DB is read-only' do
+      before do
+        allow(Gitlab::Database).to receive(:read_only?) { true }
+      end
+
+      it 'returns a list of user IDs' do
+        merge_request = create(:merge_request, assignee_id: user.id)
+
+        expect(merge_request.assignee_ids).to be_a(Array)
+        expect(merge_request.assignee_ids).to eq([user.id])
+      end
+
+      it 'returns an empty relation if no assignee_id is set' do
+        merge_request = create(:merge_request, assignee_id: nil)
+
+        expect(merge_request.assignee_ids).to be_a(Array)
+        expect(merge_request.assignee_ids).to eq([])
+      end
+    end
+  end
+end
diff --git a/spec/models/concerns/issuable_spec.rb b/spec/models/concerns/issuable_spec.rb
index 27ed298ae08..64f02978d79 100644
--- a/spec/models/concerns/issuable_spec.rb
+++ b/spec/models/concerns/issuable_spec.rb
@@ -502,8 +502,8 @@ describe Issuable do
       let(:user2) { create(:user) }
 
       before do
-        merge_request.update(assignee: user)
-        merge_request.update(assignee: user2)
+        merge_request.update(assignees: [user])
+        merge_request.update(assignees: [user, user2])
         expect(Gitlab::HookData::IssuableBuilder)
           .to receive(:new).with(merge_request).and_return(builder)
       end
@@ -512,8 +512,7 @@ describe Issuable do
         expect(builder).to receive(:build).with(
           user: user,
           changes: hash_including(
-            'assignee_id' => [user.id, user2.id],
-            'assignee' => [user.hook_attrs, user2.hook_attrs]
+            'assignees' => [[user.hook_attrs], [user.hook_attrs, user2.hook_attrs]]
           ))
 
         merge_request.to_hook_data(user, old_associations: { assignees: [user] })