1 files changed, 147 insertions, 0 deletions
diff --git a/spec/lib/gitlab/batch_pop_queueing_spec.rb b/spec/lib/gitlab/batch_pop_queueing_spec.rb
new file mode 100644
index 00000000000..28984d52024
--- /dev/null
+++ b/spec/lib/gitlab/batch_pop_queueing_spec.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::BatchPopQueueing do
+  include ExclusiveLeaseHelpers
+  using RSpec::Parameterized::TableSyntax
+
+  describe '#initialize' do
+    where(:namespace, :queue_id, :expect_error, :error_type) do
+      'feature'  | '1' | false  | nil
+      :feature   | '1' | false  | nil
+      nil        | '1' | true   | NoMethodError
+      'feature'  | nil | true   | NoMethodError
+      ''         | '1' | true   | ArgumentError
+      'feature'  | ''  | true   | ArgumentError
+      'feature'  | 1   | true   | NoMethodError
+    end
+
+    with_them do
+      it do
+        if expect_error
+          expect { described_class.new(namespace, queue_id) }.to raise_error(error_type)
+        else
+          expect { described_class.new(namespace, queue_id) }.not_to raise_error
+        end
+      end
+    end
+  end
+
+  describe '#safe_execute', :clean_gitlab_redis_queues do
+    subject { queue.safe_execute(new_items, lock_timeout: lock_timeout) }
+
+    let(:queue) { described_class.new(namespace, queue_id) }
+    let(:namespace) { 'feature' }
+    let(:queue_id) { '1' }
+    let(:lock_timeout) { 10.minutes }
+    let(:new_items) { %w[A B] }
+    let(:lock_key) { queue.send(:lock_key) }
+    let(:queue_key) { queue.send(:queue_key) }
+
+    it 'enqueues new items always' do
+      Gitlab::Redis::Queues.with do |redis|
+        expect(redis).to receive(:sadd).with(queue_key, new_items)
+        expect(redis).to receive(:expire).with(queue_key, (lock_timeout + described_class::EXTRA_QUEUE_EXPIRE_WINDOW).to_i)
+      end
+
+      subject
+    end
+
+    it 'yields the new items with exclusive lease' do
+      uuid = 'test'
+      expect_to_obtain_exclusive_lease(lock_key, uuid, timeout: lock_timeout)
+      expect_to_cancel_exclusive_lease(lock_key, uuid)
+
+      expect { |b| queue.safe_execute(new_items, lock_timeout: lock_timeout, &b) }
+        .to yield_with_args(match_array(new_items))
+    end
+
+    it 'returns the result and no items in the queue' do
+      expect(subject[:status]).to eq(:finished)
+      expect(subject[:new_items]).to be_empty
+
+      Gitlab::Redis::Queues.with do |redis|
+        expect(redis.llen(queue_key)).to be(0)
+      end
+    end
+
+    context 'when new items are enqueued during the process' do
+      it 'returns the result with newly added items' do
+        result = queue.safe_execute(new_items) do
+          queue.safe_execute(['C'])
+        end
+
+        expect(result[:status]).to eq(:finished)
+        expect(result[:new_items]).to eq(['C'])
+
+        Gitlab::Redis::Queues.with do |redis|
+          expect(redis.scard(queue_key)).to be(1)
+        end
+      end
+    end
+
+    context 'when interger items are enqueued' do
+      let(:new_items) { [1, 2, 3] }
+
+      it 'yields as String values' do
+        expect { |b| queue.safe_execute(new_items, lock_timeout: lock_timeout, &b) }
+          .to yield_with_args(%w[1 2 3])
+      end
+    end
+
+    context 'when the queue key does not exist in Redis' do
+      before do
+        allow(queue).to receive(:enqueue) { }
+      end
+
+      it 'yields empty array' do
+        expect { |b| queue.safe_execute(new_items, lock_timeout: lock_timeout, &b) }
+          .to yield_with_args([])
+      end
+    end
+
+    context 'when the other process has already been working on the queue' do
+      before do
+        stub_exclusive_lease_taken(lock_key, timeout: lock_timeout)
+      end
+
+      it 'does not yield the block' do
+        expect { |b| queue.safe_execute(new_items, lock_timeout: lock_timeout, &b) }
+          .not_to yield_control
+      end
+
+      it 'returns the result' do
+        expect(subject[:status]).to eq(:enqueued)
+      end
+    end
+
+    context 'when a duplicate item is enqueued' do
+      it 'returns the poped items to the queue and raise an error' do
+        expect { |b| queue.safe_execute(%w[1 1 2 2], &b) }
+          .to yield_with_args(match_array(%w[1 2]))
+      end
+    end
+
+    context 'when there are two queues' do
+      it 'enqueues items to each queue' do
+        queue_1 = described_class.new(namespace, '1')
+        queue_2 = described_class.new(namespace, '2')
+
+        result_2 = nil
+
+        result_1 = queue_1.safe_execute(['A']) do |_|
+          result_2 = queue_2.safe_execute(['B']) do |_|
+            queue_1.safe_execute(['C'])
+            queue_2.safe_execute(['D'])
+          end
+        end
+
+        expect(result_1[:status]).to eq(:finished)
+        expect(result_1[:new_items]).to eq(['C'])
+        expect(result_2[:status]).to eq(:finished)
+        expect(result_2[:new_items]).to eq(['D'])
+      end
+    end
+  end
+end