Deleting a user shouldn't delete associated issues.

- "Associated" issues are issues the user has created + issues that the
  user is assigned to.

- Issues that a user owns are transferred to a "Ghost User" (just a
  regular user with `state = 'ghost'` that is created when
  `User.ghost` is called).

- Issues that a user is assigned to are moved to the "Unassigned" state.

- Fix a spec failure in `profile_spec` — a spec was asserting that when a user
  is deleted, `User.count` decreases by 1. After this change, deleting a user
  creates (potentially) a ghost user, causing `User.count` not to change. The
  spec has been updated to look for the relevant user in the assertion.

1 files changed, 38 insertions, 1 deletions

diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index b69fd24c586..00e7927bf90 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -22,7 +22,7 @@ describe User, models: true do
     it { is_expected.to have_many(:deploy_keys).dependent(:destroy) }
     it { is_expected.to have_many(:events).dependent(:destroy) }
     it { is_expected.to have_many(:recent_events).class_name('Event') }
-    it { is_expected.to have_many(:issues).dependent(:destroy) }
+    it { is_expected.to have_many(:issues).dependent(:restrict_with_exception) }
     it { is_expected.to have_many(:notes).dependent(:destroy) }
     it { is_expected.to have_many(:assigned_issues).dependent(:nullify) }
     it { is_expected.to have_many(:merge_requests).dependent(:destroy) }
@@ -1490,4 +1490,41 @@ describe User, models: true do
       expect(user.admin).to be true
     end
   end
+
+  describe '.ghost' do
+    it "creates a ghost user if one isn't already present" do
+      ghost = User.ghost
+
+      expect(ghost).to be_ghost
+      expect(ghost).to be_persisted
+    end
+
+    it "does not create a second ghost user if one is already present" do
+      expect do
+        User.ghost
+        User.ghost
+      end.to change { User.count }.by(1)
+      expect(User.ghost).to eq(User.ghost)
+    end
+
+    context "when a regular user exists with the username 'ghost'" do
+      it "creates a ghost user with a non-conflicting username" do
+        create(:user, username: 'ghost')
+        ghost = User.ghost
+
+        expect(ghost).to be_persisted
+        expect(ghost.username).to eq('ghost0')
+      end
+    end
+
+    context "when a regular user exists with the email 'ghost@example.com'" do
+      it "creates a ghost user with a non-conflicting email" do
+        create(:user, email: 'ghost@example.com')
+        ghost = User.ghost
+
+        expect(ghost).to be_persisted
+        expect(ghost.email).to eq('ghost0@example.com')
+      end
+    end
+  end
 end