1 files changed, 87 insertions, 0 deletions
diff --git a/spec/lib/gitlab/database/migrations/test_batched_background_runner_spec.rb b/spec/lib/gitlab/database/migrations/test_batched_background_runner_spec.rb
new file mode 100644
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+++ b/spec/lib/gitlab/database/migrations/test_batched_background_runner_spec.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Database::Migrations::TestBatchedBackgroundRunner, :freeze_time do
+  include Gitlab::Database::MigrationHelpers
+  include Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers
+  include Database::MigrationTestingHelpers
+
+  let(:result_dir) { Dir.mktmpdir }
+
+  after do
+    FileUtils.rm_rf(result_dir)
+  end
+
+  let(:connection) { ApplicationRecord.connection }
+
+  let(:table_name) { "_test_column_copying"}
+
+  before do
+    connection.execute(<<~SQL)
+      CREATE TABLE #{table_name} (
+        id bigint primary key not null,
+        data bigint
+      );
+
+      insert into #{table_name} (id) select i from generate_series(1, 1000) g(i);
+    SQL
+  end
+
+  context 'running a real background migration' do
+    it 'runs sampled jobs from the batched background migration' do
+      queue_batched_background_migration('CopyColumnUsingBackgroundMigrationJob',
+                                         table_name, :id,
+                                         :id, :data,
+                                         batch_size: 100,
+                                         job_interval: 5.minutes) # job_interval is skipped when testing
+      described_class.new(result_dir: result_dir, connection: connection).run_jobs(for_duration: 1.minute)
+      unmigrated_row_count = define_batchable_model(table_name).where('id != data').count
+
+      expect(unmigrated_row_count).to eq(0)
+    end
+  end
+
+  context 'with jobs to run' do
+    let(:migration_name) { 'TestBackgroundMigration' }
+
+    before do
+      queue_batched_background_migration(migration_name, table_name, :id, job_interval: 5.minutes, batch_size: 100)
+    end
+
+    it 'samples jobs' do
+      calls = []
+      define_background_migration(migration_name) do |*args|
+        calls << args
+      end
+
+      described_class.new(result_dir: result_dir, connection: connection).run_jobs(for_duration: 3.minutes)
+
+      expect(calls.count).to eq(10) # 1000 rows / batch size 100 = 10
+    end
+
+    context 'with multiple jobs to run' do
+      it 'runs all jobs created within the last 48 hours' do
+        old_migration = define_background_migration(migration_name)
+
+        travel 3.days
+
+        new_migration = define_background_migration('NewMigration') { travel 1.second }
+        queue_batched_background_migration('NewMigration', table_name, :id,
+                                           job_interval: 5.minutes,
+                                           batch_size: 10,
+                                           sub_batch_size: 5)
+
+        other_new_migration = define_background_migration('NewMigration2') { travel 2.seconds }
+        queue_batched_background_migration('NewMigration2', table_name, :id,
+                                           job_interval: 5.minutes,
+                                           batch_size: 10,
+                                           sub_batch_size: 5)
+
+        expect_migration_runs(new_migration => 3, other_new_migration => 2, old_migration => 0) do
+          described_class.new(result_dir: result_dir, connection: connection).run_jobs(for_duration: 5.seconds)
+        end
+      end
+    end
+  end
+end