Add PoC of ActiveRecord migration testing

config/database.yml.postgresql

@@ -46,3 +46,14 @@ test: &test
   username: postgres
   password:
   # host: localhost
+
+# Warning: The database defined as "migrate" might erased.
+# Do not set this db to the same as development or production.
+migrate: &test
+  adapter: postgresql
+  encoding: unicode
+  database: gitlabhq_migrate
+  pool: 5
+  username: postgres
+  password:
+  # host: localhost

db/migrate/20170525132202_migrate_pipeline_stages.rb

+class MigratePipelineStages < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def change
+    create_table :ci_stages do |t|
+      t.integer :project_id
+      t.integer :pipeline_id
+      t.string :name
+      t.timestamps
+    end
+  end
+end

spec/migrations/migrate_pipeline_stages_spec.rb

+require 'migrations_helper'
+require Rails.root.join('db', 'migrate', '20170525132202_migrate_pipeline_stages.rb')
+
+describe MigratePipelineStages, :migration do
+  ##
+  # Create tables using schema from which we will migrate stuff.
+  #
+  before do
+    ActiveRecord::Schema.define(version: 20170523091700) do
+      enable_extension "plpgsql"
+      enable_extension "pg_trgm"
+
+      create_table "ci_pipelines", force: :cascade do |t|
+        t.string "ref"
+        t.string "sha"
+        t.string "before_sha"
+        t.datetime "created_at"
+        t.datetime "updated_at"
+        t.boolean "tag", default: false
+        t.text "yaml_errors"
+        t.datetime "committed_at"
+        t.integer "project_id"
+        t.string "status"
+        t.datetime "started_at"
+        t.datetime "finished_at"
+        t.integer "duration"
+        t.integer "user_id"
+        t.integer "lock_version"
+        t.integer "auto_canceled_by_id"
+        t.integer "pipeline_schedule_id"
+      end
+
+      add_index "ci_pipelines", ["auto_canceled_by_id"], name: "index_ci_pipelines_on_auto_canceled_by_id", using: :btree
+      add_index "ci_pipelines", ["pipeline_schedule_id"], name: "index_ci_pipelines_on_pipeline_schedule_id", using: :btree
+      add_index "ci_pipelines", ["project_id", "ref", "status"], name: "index_ci_pipelines_on_project_id_and_ref_and_status", using: :btree
+      add_index "ci_pipelines", ["project_id", "sha"], name: "index_ci_pipelines_on_project_id_and_sha", using: :btree
+      add_index "ci_pipelines", ["project_id"], name: "index_ci_pipelines_on_project_id", using: :btree
+      add_index "ci_pipelines", ["status"], name: "index_ci_pipelines_on_status", using: :btree
+      add_index "ci_pipelines", ["user_id"], name: "index_ci_pipelines_on_user_id", using: :btree
+
+      create_table "ci_builds", force: :cascade do |t|
+        t.string "status"
+        t.datetime "finished_at"
+        t.text "trace"
+        t.datetime "created_at"
+        t.datetime "updated_at"
+        t.datetime "started_at"
+        t.integer "runner_id"
+        t.float "coverage"
+        t.integer "commit_id"
+        t.text "commands"
+        t.string "name"
+        t.text "options"
+        t.boolean "allow_failure", default: false, null: false
+        t.string "stage"
+        t.integer "trigger_request_id"
+        t.integer "stage_idx"
+        t.boolean "tag"
+        t.string "ref"
+        t.integer "user_id"
+        t.string "type"
+        t.string "target_url"
+        t.string "description"
+        t.text "artifacts_file"
+        t.integer "project_id"
+        t.text "artifacts_metadata"
+        t.integer "erased_by_id"
+        t.datetime "erased_at"
+        t.datetime "artifacts_expire_at"
+        t.string "environment"
+        t.integer "artifacts_size", limit: 8
+        t.string "when"
+        t.text "yaml_variables"
+        t.datetime "queued_at"
+        t.string "token"
+        t.integer "lock_version"
+        t.string "coverage_regex"
+        t.integer "auto_canceled_by_id"
+        t.boolean "retried"
+      end
+
+      add_index "ci_builds", ["auto_canceled_by_id"], name: "index_ci_builds_on_auto_canceled_by_id", using: :btree
+      add_index "ci_builds", ["commit_id", "stage_idx", "created_at"], name: "index_ci_builds_on_commit_id_and_stage_idx_and_created_at", using: :btree
+      add_index "ci_builds", ["commit_id", "status", "type"], name: "index_ci_builds_on_commit_id_and_status_and_type", using: :btree
+      add_index "ci_builds", ["commit_id", "type", "name", "ref"], name: "index_ci_builds_on_commit_id_and_type_and_name_and_ref", using: :btree
+      add_index "ci_builds", ["commit_id", "type", "ref"], name: "index_ci_builds_on_commit_id_and_type_and_ref", using: :btree
+      add_index "ci_builds", ["project_id"], name: "index_ci_builds_on_project_id", using: :btree
+      add_index "ci_builds", ["runner_id"], name: "index_ci_builds_on_runner_id", using: :btree
+      add_index "ci_builds", ["status", "type", "runner_id"], name: "index_ci_builds_on_status_and_type_and_runner_id", using: :btree
+      add_index "ci_builds", ["status"], name: "index_ci_builds_on_status", using: :btree
+      add_index "ci_builds", ["token"], name: "index_ci_builds_on_token", unique: true, using: :btree
+      add_index "ci_builds", ["updated_at"], name: "index_ci_builds_on_updated_at", using: :btree
+      add_index "ci_builds", ["user_id"], name: "index_ci_builds_on_user_id", using: :btree
+    end
+  end
+
+  let(:pipeline) do
+    Class.new(ActiveRecord::Base) do
+      self.table_name = 'ci_pipelines'
+    end
+  end
+
+  let(:build) do
+    Class.new(ActiveRecord::Base) do
+      self.table_name = 'ci_builds'
+    end
+  end
+
+  let(:stage) do
+    Class.new(ActiveRecord::Base) do
+      self.table_name = 'ci_stages'
+    end
+  end
+
+  ##
+  # Create test data
+  #
+  before do
+    pipeline.create!(ref: 'master', sha: 'adf43c3a')
+  end
+
+  it 'correctly migrates pipeline stages' do
+    described_class.new.change
+
+    expect(stage.table_exists?).to be true
+  end
+end

spec/migrations_helper.rb

+require File.expand_path("../../config/environment", __FILE__)
+require 'rspec/rails'
+require 'shoulda/matchers'
+
+ActiveRecord::Base.establish_connection(:migrate)
+
+RSpec.configure do |config|
+  config.mock_with :rspec
+  config.verbose_retry = true
+  config.display_try_failure_messages = true
+  config.use_transactional_fixtures = true
+  config.infer_spec_type_from_file_location!
+  config.raise_errors_for_deprecations!
+
+  config.around(:each, :migration) do |example|
+    ActiveRecord::Tasks::DatabaseTasks.purge_current
+
+    example.run
+
+    ActiveRecord::Tasks::DatabaseTasks.purge_current
+  end
+
+  config.around(:each, :redis) do |example|
+    Gitlab::Redis.with(&:flushall)
+    Sidekiq.redis(&:flushall)
+
+    example.run
+
+    Gitlab::Redis.with(&:flushall)
+    Sidekiq.redis(&:flushall)
+  end
+end
+
+
+puts "Rails environment: #{Rails.env}"
+puts "Database connection: #{ActiveRecord::Base.connection_config[:database]}"