MysqlRewinder is a simple, stable, and fast database cleaner for mysql.

• Fast cleanup using DELETE query
• Supports multi-database
• Supports both mysql2 and trilogy as a client library
• Works without ActiveRecord
• Works with fork

1. Capture SQL statements during test execution and extract INSERTed table names, and record them into temporary files
2. Aggregate tmp files and execute DELETE query for INSERTed tables

MysqlRewinder is stable because it does not depend on ActiveRecord's internal implementation. It only depends on Mysql2::Client#query and Trilogy#query.

Add this line to your Gemfile's :test group:

gem 'trilogy'
# gem 'mysql2' # described later
gem 'mysql_rewinder'

And then execute:

$ bundle

RSpec.configure do |config|
  config.before(:suite) do
    db_config = {
      host: '127.0.0.1',
      port: '3306',
      username: 'user1',
      password: 'my_secure_password',
      database: 'myapp-test'
    }
    MysqlRewinder.setup([db_config])
    MysqlRewinder.clean_all
  end

  config.after(:each) do
    MysqlRewinder.clean
  end
end

Pass all configurations to MysqlRewinder.setup.

MysqlRewinder.setup(
  [
    { host: '127.0.0.1', port: '3306', username: 'user1', password: 'my_secure_password', database: 'myapp-test-shard1' },
    { host: '127.0.0.1', port: '3306', username: 'user1', password: 'my_secure_password', database: 'myapp-test-shard2' },
  ]
)

If you want to use mysql2 as a client library, do the following:

• Write gem 'mysql2' in your Gemfile
• Pass adapter: :mysql2 to MysqlRewinder.setup.

MysqlRewinder.setup(db_configs, adapter: :mysql2)

If you want to use MysqlRewinder with ActiveRecord, do the following:

• Generate db_configs from ActiveRecord::Base.configurations
• Pass ActiveRecord::SchemaMigration.new(nil).table_name and ActiveRecord::Base.internal_metadata_table_name to MysqlRewinder.setup as except_tables

db_configs = ActiveRecord::Base.configurations.configs_for(env_name: 'test').map(&:configuration_hash)
except_tables = [
  ActiveRecord::Base.internal_metadata_table_name,

  # for AR >= 7.1
  ActiveRecord::SchemaMigration.new(nil).table_name,
  # for AR < 7.1
  # ActiveRecord::SchemaMigration.table_name,
]

MysqlRewinder.setup(db_configs, except_tables: except_tables)

If you want to enable logging, specify logger for MysqlRewinder.setup

MysqlRewinder.setup(db_configs, logger: Logger.new(STDOUT))

Bug reports and pull requests are welcome on GitHub at https://github.com/DeNA/mysql_rewinder. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

Everyone interacting in the MysqlRewinder project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

The gem is available as open source under the terms of the MIT License.

• Thank you @aeroastro for the idea of using temporary files
• This gem is heavily inspired by amatsuda/database_rewinder.