💎 Ruby DNS mock. Mimic any DNS records for your test environment and even more.

Table of Contents

• Features
• Requirements
• Installation
• Usage
  • RSpec
    • DnsMock RSpec helper
    • DnsMock RSpec interface
• Contributing
• License
• Code of Conduct
• Credits
• Versioning
• Changelog

Features

• Ability to mimic any DNS records (A, AAAA, CNAME, MX, NS, PTR, SOA, SRV and TXT)
• Automatically converts host names to RDNS/Punycode representation
• Lightweight UDP DNS mock server with dynamic/manual port assignment
• Test framework agnostic (it's PORO, so you can use it outside of RSpec, Test::Unit or MiniTest)
• Simple and intuitive DSL
• Only one runtime dependency

Requirements

Ruby MRI 2.5.0+

Installation

Add this line to your application's Gemfile:

group :development, :test do
  gem 'dns_mock', require: false
end

And then execute:

bundle

Or install it yourself as:

gem install dns_mock

Usage

# Example of mocked DNS records, please follow this data structure

records = {
  'example.com' => {
    a: %w[1.1.1.1 2.2.2.2],
    aaaa: %w[2a00:1450:4001:81e::200e],
    ns: %w[ns1.domain.com ns2.domain.com],
    mx: %w[mx1.domain.com mx2.domain.com:50], # you can specify host(s) or host(s) with priority, use '.:0' for definition null MX record
    txt: %w[txt_record_1 txt_record_2],
    cname: 'mañana.com', # you can specify hostname in UTF-8. It will be converted to xn--maana-pta.com automatically
    soa: [
      {
        mname: 'dns1.domain.com',
        rname: 'dns2.domain.com',
        serial: 2_035_971_683,
        refresh: 10_000,
        retry: 2_400,
        expire: 604_800,
        minimum: 3_600
      }
    ]
  },
  '1.2.3.4' => { # You can define RDNS host address without lookup prefix. It will be converted to 4.3.2.1.in-addr.arpa automatically
    ptr: %w[domain_1.com domain_2.com]
  },
  '_sip._tcp.example.com' => { # Please use {_service._proto.domain} pattern to follow the valid RFC-2782 SRV host pattern representation
    srv: [
      {
        priority: 0,
        weight: 10,
        port: 5_060,
        target: 'domain.com'
      }
    ]
  }
}

# Public DnsMock interface
# records:Hash, port:Integer, exception_if_not_found:Boolean
# are optional params. By default creates dns mock server with
# empty records. A free port for server will be randomly assigned
# in the range from 49152 to 65535, if record not found exception
# won't raises. Please note if you specify zero port number,
# free port number will be randomly assigned as a server port too.
# Returns current dns mock server
dns_mock_server = DnsMock.start_server(records: records) # => DnsMock::Server instance

# returns current dns mock server port
dns_mock_server.port # => 49322

# returns current collected server lookup messsages
# represented as array of Resolv::DNS::Message instances
dns_mock_server.messages # => [#<Resolv::DNS::Message>]

# interface to setup mock records.
# Available only in case when server mocked records is empty
dns_mock_server.assign_mocks(records) # => true/nil

# interface to reset current mocked records
dns_mock_server.reset_mocks! # => true

# interface to clear collected lookup messages
dns_mock_server.clear_messages! # => true

# interface to stop current dns mock server
dns_mock_server.stop! # => true

# returns list of running dns mock servers
DnsMock.running_servers # => [DnsMock::Server instance]

# interface to stop all running dns mock servers
DnsMock.stop_running_servers! # => true

RSpec

Require this either in your Gemfile or in RSpec's support scripts. So either:

# Gemfile

group :test do
  gem 'rspec'
  gem 'dns_mock', require: 'dns_mock/test_framework/rspec'
end

or

# spec/support/config/dns_mock.rb

require 'dns_mock/test_framework/rspec'

DnsMock RSpec helper

Just add DnsMock::TestFramework::RSpec::Helper if you wanna use shortcut dns_mock_server for DnsMock server instance inside of your RSpec.describe blocks:

# spec/support/config/dns_mock.rb

RSpec.configure do |config|
  config.include DnsMock::TestFramework::RSpec::Helper
end

# Your awesome first_a_record_spec.rb

RSpec.describe FirstARecord do
  subject(:service) do
    described_class.call(
      hostname,
      dns_gateway_host: 'localhost',
      dns_gateway_port: dns_mock_server.port
    )
  end

  let(:hostname) { 'example.com' }
  let(:first_a_record) { '1.2.3.4' }
  let(:records) { { hostname => { a: [first_a_record] } } }

  before { dns_mock_server.assign_mocks(records) }

  it { is_expected.to eq(first_a_record) }
end

DnsMock RSpec interface

If you won't use DnsMock::TestFramework::RSpec::Helper you can use DnsMock::TestFramework::RSpec::Interface directly instead:

DnsMock::TestFramework::RSpec::Interface.start_server    # creates and runs DnsMock server instance
DnsMock::TestFramework::RSpec::Interface.stop_server!    # stops current DnsMock server instance
DnsMock::TestFramework::RSpec::Interface.reset_mocks!    # resets mocks in current DnsMock server instance
DnsMock::TestFramework::RSpec::Interface.clear_server!   # stops and clears current DnsMock server instance

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/mocktools/ruby-dns-mock. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct. Please check the open tickets. Be sure to follow Contributor Code of Conduct below and our Contributing Guidelines.

License

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

Code of Conduct

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

Credits

• The Contributors for code and awesome suggestions
• The Stargazers for showing their support

Versioning

DnsMock uses Semantic Versioning 2.0.0