Add basic coverage for UnmergeWorker job (#39398)

spec/workers/unmerge_worker_spec.rb

@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe UnmergeWorker do
+  let(:worker) { described_class.new }
+
+  describe '#perform' do
+    subject { worker.perform(account_id, into_id, type) }
+
+    let(:account_id) { account.id }
+    let(:account) { Fabricate :account }
+    let(:into_id) { nil }
+    let(:type) { nil }
+
+    context 'when account is invalid' do
+      let(:account_id) { 123_123_123 }
+
+      it { is_expected.to be(true) }
+    end
+
+    context 'when type is invalid' do
+      it { is_expected.to be_nil }
+    end
+
+    context 'when type is list' do
+      let(:type) { 'list' }
+
+      context 'when target is invalid' do
+        let(:into_id) { 123_123_123 }
+
+        it { is_expected.to be(true) }
+      end
+
+      context 'when target is valid' do
+        let(:into_id) { list.id }
+        let(:list) { Fabricate :list }
+
+        let(:manager_service) { instance_double(FeedManager, unmerge_from_list: nil) }
+
+        before { allow(FeedManager).to receive(:instance).and_return manager_service }
+
+        it 'unmerges from list feed' do
+          subject
+
+          expect(manager_service)
+            .to have_received(:unmerge_from_list).with(account, list)
+        end
+      end
+    end
+
+    context 'when type is home' do
+      let(:type) { 'home' }
+
+      context 'when target is invalid' do
+        let(:into_id) { 123_123_123 }
+
+        it { is_expected.to be(true) }
+      end
+
+      context 'when target is valid' do
+        let(:into_id) { target_account.id }
+        let(:target_account) { Fabricate :account }
+
+        let(:manager_service) { instance_double(FeedManager, unmerge_from_home: nil) }
+
+        before { allow(FeedManager).to receive(:instance).and_return manager_service }
+
+        it 'unmerges from list feed' do
+          subject
+
+          expect(manager_service)
+            .to have_received(:unmerge_from_home).with(account, target_account)
+        end
+      end
+    end
+  end
+end