1 files changed, 82 insertions, 0 deletions
diff --git a/spec/lib/generators/batched_background_migration/batched_background_migration_generator_spec.rb b/spec/lib/generators/batched_background_migration/batched_background_migration_generator_spec.rb
new file mode 100644
index 00000000000..d533bcf0039
--- /dev/null
+++ b/spec/lib/generators/batched_background_migration/batched_background_migration_generator_spec.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'rails/generators/testing/behaviour'
+require 'rails/generators/testing/assertions'
+
+RSpec.describe BatchedBackgroundMigration::BatchedBackgroundMigrationGenerator, feature_category: :database do
+  include Rails::Generators::Testing::Behaviour
+  include Rails::Generators::Testing::Assertions
+  include FileUtils
+
+  tests described_class
+  destination File.expand_path('tmp', __dir__)
+
+  before do
+    prepare_destination
+  end
+
+  after do
+    rm_rf(destination_root)
+  end
+
+  context 'with valid arguments' do
+    let(:expected_migration_file) { load_expected_file('queue_my_batched_migration.txt') }
+    let(:expected_migration_spec_file) { load_expected_file('queue_my_batched_migration_spec.txt') }
+    let(:expected_migration_job_file) { load_expected_file('my_batched_migration.txt') }
+    let(:expected_migration_job_spec_file) { load_expected_file('my_batched_migration_spec_matcher.txt') }
+    let(:expected_migration_dictionary) { load_expected_file('my_batched_migration_dictionary_matcher.txt') }
+
+    it 'generates expected files' do
+      run_generator %w[my_batched_migration --table_name=projects --column_name=id --feature_category=database]
+
+      assert_migration('db/post_migrate/queue_my_batched_migration.rb') do |migration_file|
+        expect(migration_file).to eq(expected_migration_file)
+      end
+
+      assert_migration('spec/migrations/queue_my_batched_migration_spec.rb') do |migration_spec_file|
+        expect(migration_spec_file).to eq(expected_migration_spec_file)
+      end
+
+      assert_file('lib/gitlab/background_migration/my_batched_migration.rb') do |migration_job_file|
+        expect(migration_job_file).to eq(expected_migration_job_file)
+      end
+
+      assert_file('spec/lib/gitlab/background_migration/my_batched_migration_spec.rb') do |migration_job_spec_file|
+        # Regex is used to match the dynamic schema: <version> in the specs
+        expect(migration_job_spec_file).to match(/#{expected_migration_job_spec_file}/)
+      end
+
+      assert_file('db/docs/batched_background_migrations/my_batched_migration.yml') do |migration_dictionary|
+        # Regex is used to match the dynamically generated 'milestone' in the dictionary
+        expect(migration_dictionary).to match(/#{expected_migration_dictionary}/)
+      end
+    end
+  end
+
+  context 'without required arguments' do
+    it 'throws table_name is required error' do
+      expect do
+        run_generator %w[my_batched_migration]
+      end.to raise_error(ArgumentError, 'table_name is required')
+    end
+
+    it 'throws column_name is required error' do
+      expect do
+        run_generator %w[my_batched_migration --table_name=projects]
+      end.to raise_error(ArgumentError, 'column_name is required')
+    end
+
+    it 'throws feature_category is required error' do
+      expect do
+        run_generator %w[my_batched_migration --table_name=projects --column_name=id]
+      end.to raise_error(ArgumentError, 'feature_category is required')
+    end
+  end
+
+  private
+
+  def load_expected_file(file_name)
+    File.read(File.expand_path("expected_files/#{file_name}", __dir__))
+  end
+end