diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 0000000..524f3c4
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,22 @@
+---
+name: coverage
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: Install Ruby (2.7)
+      uses: actions/setup-ruby@v1
+      with:
+        ruby-version: 2.7.x
+    - uses: amancevice/setup-code-climate@v0
+      with:
+        cc_test_reporter_id: ${{ secrets.CC_TEST_REPORTER_ID }}
+    - run: cc-test-reporter before-build
+    - name: Build and test with RSpec
+      run: |
+        gem install bundler
+        bundle install --jobs 4 --retry 3
+        bundle exec rspec
+    - run: cc-test-reporter after-build
diff --git a/.github/workflows/danger.yml b/.github/workflows/danger.yml
new file mode 100644
index 0000000..c24890a
--- /dev/null
+++ b/.github/workflows/danger.yml
@@ -0,0 +1,20 @@
+---
+name: danger
+on:
+  pull_request:
+    types: [opened, reopened, edited, synchronize]
+jobs:
+  danger:
+    runs-on: ubuntu-20.04
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 2.6
+        bundler-cache: true
+    - name: Run Danger
+      run: |
+        # the personal token is public, this is ok, base64 encode to avoid tripping Github
+        TOKEN=$(echo -n NWY1ZmM5MzEyMzNlYWY4OTZiOGU3MmI3MWQ3Mzk0MzgxMWE4OGVmYwo= | base64 --decode)
+        DANGER_GITHUB_API_TOKEN=$TOKEN bundle exec danger --verbose
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..9267ca8
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,38 @@
+---
+name: test
+on: [push, pull_request]
+jobs:
+  lint:
+    name: RuboCop
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.7
+          bundler-cache: true
+      - name: Run RuboCop
+        run: bundle exec rubocop
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        entry:
+          - { ruby: 2.4, allowed-failure: false }
+          - { ruby: 2.5, allowed-failure: false }
+          - { ruby: 2.6, allowed-failure: false }
+          - { ruby: 2.7, allowed-failure: false }
+          - { ruby: 3.0, allowed-failure: false }
+          - { ruby: ruby-head, allowed-failure: true }
+          - { ruby: truffleruby-head, allowed-failure: true }
+          - { ruby: jruby-head, allowed-failure: true }
+    name: test (${{ matrix.entry.ruby }})
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.entry.ruby }}
+      - run: bundle install --jobs=3 --retry=3 --path=vendor/bundle
+      - run: bundle exec rake spec
+        continue-on-error: ${{ matrix.entry.allowed-failure }}
diff --git a/.gitignore b/.gitignore
index a3e145b..70c558c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 Gemfile.lock
 pkg
+coverage
diff --git a/.rubocop.yml b/.rubocop.yml
index c9fe898..08c82d3 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -3,6 +3,10 @@ AllCops:
   Exclude:
     - vendor/**/*
 
+Metrics/BlockLength:
+  Exclude:
+    - 'spec/**/*_spec.rb'
+
 Style/HashEachMethods:
   Enabled: true
 
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index fb39a03..81fac83 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -6,12 +6,6 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 1
-# Configuration parameters: CountComments, ExcludedMethods.
-# ExcludedMethods: refine
-Metrics/BlockLength:
-  Max: 180
-
 # Offense count: 1
 # Configuration parameters: ExpectMatchingDefinition, Regex, IgnoreExecutableScripts, AllowedAcronyms.
 # AllowedAcronyms: CLI, DSL, ACL, API, ASCII, CPU, CSS, DNS, EOF, GUID, HTML, HTTP, HTTPS, ID, IP, JSON, LHS, QPS, RAM, RHS, RPC, SLA, SMTP, SQL, SSH, TCP, TLS, TTL, UDP, UI, UID, UUID, URI, URL, UTF8, VM, XML, XMPP, XSRF, XSS
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index d355d4f..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,18 +0,0 @@
-language: ruby
-
-cache: bundler
-
-before_install:
-  - gem update --system
-
-rvm:
-  - 2.6.5
-  - 2.4.0
-  - 2.3.1
-  - ruby-head
-  - jruby-head
-
-matrix:
-  allow_failures:
-    - rvm: ruby-head
-    - rvm: jruby-head
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d268a78..6566fe7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,42 +1,50 @@
-### 0.8.0 (2020/3/27)
+### 0.9.0 (2021/01/21)
+
+* [#34](https://github.com/dblock/ruby-enum/pull/34): Added support for Ruby 3.0 - [@dblock](https://github.com/dblock).
+* [#29](https://github.com/dblock/ruby-enum/pull/29): Added superclass values when enumerating with `Ruby::Enum#values` - [@gi](https://github.com/gi).
+* [#30](https://github.com/dblock/ruby-enum/pull/30): Default value to key - [@gi](https://github.com/gi).
+* [#34](https://github.com/dblock/ruby-enum/pull/34): Replaced Travis-CI with Github Actions, added Danger PR linter - [@dblock](https://github.com/dblock).
+* [#37](https://github.com/dblock/ruby-enum/pull/37): Added code coverage - [@dblock](https://github.com/dblock).
+
+### 0.8.0 (2020/03/27)
 
 * [#22](https://github.com/dblock/ruby-enum/pull/22): Added `Ruby::Enum#each_key` and `Ruby::Enum#each_value` - [@dblock](https://github.com/dblock).
 * [#22](https://github.com/dblock/ruby-enum/pull/22): Dropped support for Ruby 2.2 - [@dblock](https://github.com/dblock).
 * [#22](https://github.com/dblock/ruby-enum/pull/22): Upgraded RuboCop to 0.80.1 - [@dblock](https://github.com/dblock).
 
-### 0.7.2 (2017/3/15)
+### 0.7.2 (2017/03/15)
 
 * [#18](https://github.com/dblock/ruby-enum/pull/18): Added support for non constant definition - [@laertispappas](https://github.com/laertispappas).
 
-### 0.7.1 (2017/2/23)
+### 0.7.1 (2017/02/23)
 
 * [#16](https://github.com/dblock/ruby-enum/pull/16): Replaced `const_missing` with `const_set` - [@laertispappas](https://github.com/laertispappas).
 
-### 0.7.0 (2017/2/21)
+### 0.7.0 (2017/02/21)
 
 * [#3](https://github.com/dblock/ruby-enum/pull/13): Added support for subclassing an Enum - [@laertispappas](https://github.com/laertispappas).
 
-### 0.6.0 (2016/5/12)
+### 0.6.0 (2016/05/12)
 
 * [#12](https://github.com/dblock/ruby-enum/pull/12): A `Ruby::Enum::Errors::DuplicateKeyError` or a `Ruby::Enum::Errors::DuplciateKeyValyeError` will now be raised when duplicate keys / values are defined - [@laertispappas](https://github.com/laertispappas).
 
-### 0.5.0 (2015/20/11)
+### 0.5.0 (2015/11/20)
 
 * [#8](https://github.com/dblock/ruby-enum/pull/8): Added `Ruby::Enum#key`, `Ruby::Enum#value`, `Ruby::Enum#key?`, and `Ruby::Enum#value?` - [@dmolesUC3](https://github.com/dmolesUC3).
 
-### 0.4.0 (2014/29/6)
+### 0.4.0 (2014/06/29)
 
 * [#5](https://github.com/dblock/ruby-enum/pull/5): Mixed in `Enumerable` - [@kgann](https://github.com/kgann).
 
-### 0.3.0 (2014/19/5)
+### 0.3.0 (2014/05/19)
 
 * [#4](https://github.com/dblock/ruby-enum/pull/4): Added `Ruby::Enum#map` - [@ArnaudRinquin](https://github.com/ArnaudRinquin).
 
-### 0.2.1 (2013/15/5)
+### 0.2.1 (2013/05/15)
 
 * Added `Ruby::Enum#values`, `Ruby::Enum#keys` and `Ruby::Enum#to_h` - [@dblock](https://github.com/dblock).
 * A `Ruby::Enum::Errors::UninitializedConstantError` will now be raised when referencing an undefined enum - [@dblock](https://github.com/dblock).
 
-### 0.1.0 (2013/14/5)
+### 0.1.0 (2013/05/14)
 
 * Initial public release, live-coded during [May 2013 NYC.rb](http://code.dblock.org/your-first-ruby-gem) - [@dblock](https://github.com/dblock).
diff --git a/Dangerfile b/Dangerfile
new file mode 100644
index 0000000..a0a4a57
--- /dev/null
+++ b/Dangerfile
@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+changelog.check!
+toc.check!
diff --git a/Gemfile b/Gemfile
index 7089426..56badd5 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,6 +7,13 @@ gemspec
 gem 'rake'
 
 group :development, :test do
+  gem 'danger'
+  gem 'danger-changelog', '0.6.1'
+  gem 'danger-toc', '0.2.0'
   gem 'rspec', '~> 3.0'
   gem 'rubocop', '0.80.1'
 end
+
+group :test do
+  gem 'simplecov', require: false
+end
diff --git a/LICENSE.md b/LICENSE.md
index 786edf3..a450dc3 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2013-2020 Daniel Doubrovkine.
+Copyright (c) 2013-2021 Daniel Doubrovkine.
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/README.md b/README.md
index ebe23d2..1e6e66d 100644
--- a/README.md
+++ b/README.md
@@ -2,117 +2,157 @@ Ruby::Enum
 ==========
 
 [![Gem Version](http://img.shields.io/gem/v/ruby-enum.svg)](http://badge.fury.io/rb/ruby-enum)
-[![Build Status](https://travis-ci.org/dblock/ruby-enum.svg?branch=master)](https://travis-ci.org/dblock/ruby-enum)
+[![Build Status](https://github.com/dblock/ruby-enum/workflows/test/badge.svg?branch=master)](https://github.com/dblock/ruby-enum/actions)
 [![Code Climate](https://codeclimate.com/github/dblock/ruby-enum.svg)](https://codeclimate.com/github/dblock/ruby-enum)
 
-Enum-like behavior for Ruby, heavily inspired by [this](http://www.rubyfleebie.com/enumerations-and-ruby) and improved upon [another blog post](http://code.dblock.org/how-to-define-enums-in-ruby).
+Enum-like behavior for Ruby, heavily inspired by [this](http://www.rubyfleebie.com/enumerations-and-ruby), and improved upon [another blog post](http://code.dblock.org/how-to-define-enums-in-ruby).
+
+## Table of Contents
+
+- [Usage](#usage)
+  - [Constants](#constants)
+  - [Class Methods](#class-methods)
+  - [Default Value](#default-value)
+  - [Enumerating](#enumerating)
+    - [Iterating](#iterating)
+    - [Mapping](#mapping)
+    - [Reducing](#reducing)
+    - [Sorting](#sorting)
+  - [Hashing](#hashing)
+    - [Retrieving keys and values](#retrieving-keys-and-values)
+    - [Mapping keys to values](#mapping-keys-to-values)
+    - [Mapping values to keys](#mapping-values-to-keys)
+  - [Duplicate enumerator keys or duplicate values](#duplicate-enumerator-keys-or-duplicate-values)
+  - [Inheritance](#inheritance)
+- [Contributing](#contributing)
+- [Copyright and License](#copyright-and-license)
+- [Related Projects](#related-projects)
 
 ## Usage
 
-Enums can be defined and accessed either as constants or class methods, which is a matter of preference.
+Enums can be defined and accessed either as constants, or class methods, which is a matter of preference.
 
 ### Constants
 
-Define enums and reference them as constants.
+Define enums, and reference them as constants.
 
 ``` ruby
-class Colors
+class OrderState
   include Ruby::Enum
 
-  define :RED, "red"
-  define :GREEN, "green"
+  define :CREATED, 'created'
+  define :PAID, 'paid'
 end
 ```
 
 ``` ruby
-Colors::RED # "red"
-Colors::GREEN # "green"
-Colors::UNDEFINED # raises Ruby::Enum::Errors::UninitializedConstantError
-Colors.keys # [ :RED, :GREEN ]
-Colors.values # [ "red", "green" ]
-Colors.to_h # { :RED => "red", :GREEN => "green" }
+OrderState::CREATED # 'created'
+OrderState::PAID # 'paid'
+OrderState::UNKNOWN # raises Ruby::Enum::Errors::UninitializedConstantError
+OrderState.keys # [ :CREATED, :PAID ]
+OrderState.values # [ 'created', 'paid' ]
+OrderState.to_h # { :CREATED => 'created', :PAID => 'paid' }
 ```
 
 ### Class Methods
 
-Define enums reference them as class methods.
+Define enums, and reference them as class methods.
 
 ``` ruby
 class OrderState
   include Ruby::Enum
 
-  define :created, 'Created'
-  define :paid, 'Paid'
+  define :created, 'created'
+  define :paid, 'paid'
 end
 ```
 
 ```ruby
-OrderState.created # "Created"
-OrderState.paid # "Paid"
+OrderState.created # 'created'
+OrderState.paid # 'paid'
 OrderState.undefined # NoMethodError is raised
 OrderState.keys # [ :created, :paid ]
-OrderState.values # ["Created", "Paid"]
-OrderState.to_h # { :created => 'Created', :paid => 'Paid' }
+OrderState.values # ['created', 'paid']
+OrderState.to_h # { :created => 'created', :paid => 'paid' }
+```
+
+### Default Value
+
+The value is optional. If unspecified, the value will default to the key.
+
+``` ruby
+class OrderState
+  include Ruby::Enum
+
+  define :UNSPECIFIED
+  define :unspecified
+end
+```
+
+``` ruby
+OrderState::UNSPECIFIED # :UNSPECIFIED
+OrderState.unspecified # :unspecified
 ```
 
 ### Enumerating
 
-All `Enumerable` methods are supported.
+Enums support all `Enumerable` methods.
 
 #### Iterating
 
 ``` ruby
-Colors.each do |key, enum|
-  # key and enum.key is :RED, :GREEN
-  # enum.value is "red", "green"
+OrderState.each do |key, enum|
+  # key and enum.key are :CREATED, :PAID
+  # enum.value is 'created', 'paid'
 end
 ```
 
 ``` ruby
-Colors.each_key do |key|
-  # :RED, :GREEN
+OrderState.each_key do |key|
+  # :CREATED, :PAID
 end
 ```
 
 ``` ruby
-Colors.each_value do |value|
-  # "red", "green"
+OrderState.each_value do |value|
+  # 'created', 'paid'
 end
 ```
 
 #### Mapping
 
 ``` ruby
-Colors.map do |key, enum|
-  # key and enum.key is :RED, :GREEN
-  # enum.value is "red", "green"
+OrderState.map do |key, enum|
+  # key and enum.key are :CREATED, :PAID
+  # enum.value is 'created', 'paid'
   [enum.value, key]
 end
 
-# => [ ['red', :RED], ['green', :GREEN] ]
+# => [ ['created', :CREATED], ['paid', :PAID] ]
 ```
 
 #### Reducing
 
 ``` ruby
-Colors.reduce([]) do |arr, (key, enum)|
-  # key and enum.key is :RED, :GREEN
-  # enum.value is "red", "green"
+OrderState.reduce([]) do |arr, (key, enum)|
+  # key and enum.key are :CREATED, :PAID
+  # enum.value is 'created', 'paid'
   arr << [enum.value, key]
 end
 
-# => [ ['red', :RED], ['green', :GREEN] ]
+# => [ ['created', :CREATED], ['paid', :PAID] ]
 ```
 
 #### Sorting
+
 ``` ruby
-Colors.sort_by do |key, enum|
-  # key and enum.key is :RED, :GREEN
-  # enum.value is "red", "green"
-  enum.value
+OrderState.sort_by do |key, enum|
+  # key and enum.key are :CREATED, :PAID
+  # enum.value is 'created', 'paid'
+  enum.value.length
 end
 
-# => [ [:GREEN, #<Colors:...>], [:RED, #<Colors:...>] ]
+# => [[:PAID, #<OrderState:0x0 @key=:PAID, @value="paid">], [:CREATED, #<OrderState:0x1 @key=:CREATED, @value="created">]]
 ```
 
 ### Hashing
@@ -122,83 +162,110 @@ Several hash-like methods are supported.
 #### Retrieving keys and values
 
 ``` ruby
-Colors.keys
-# => [:RED, :GREEN]
+OrderState.keys
+# => [:CREATED, :PAID]
 
-Colors.values
-# => ["red", "green"]
+OrderState.values
+# => ['created', 'paid']
 ```
 
 #### Mapping keys to values
 
 ``` ruby
-Colors.key?(:RED)
+OrderState.key?(:CREATED)
 # => true
 
-Colors.value(:RED)
-# => "red"
+OrderState.value(:CREATED)
+# => 'created'
 
-Colors.key?(:BLUE)
+OrderState.key?(:FAILED)
 # => false
 
-Colors.value(:BLUE)
+OrderState.value(:FAILED)
 # => nil
 ```
 
 #### Mapping values to keys
 
 ``` ruby
-Colors.value?('green')
+OrderState.value?('paid')
 # => true
 
-Colors.key('green')
-# => :GREEN
+OrderState.key('paid')
+# => :PAID
 
-Colors.value?('yellow')
+OrderState.value?('failed')
 # => false
 
-Colors.key('yellow')
+OrderState.key('failed')
 # => nil
 ```
 
 ### Duplicate enumerator keys or duplicate values
 
-Defining duplicate enums will raise a `Ruby::Enum::Errors::DuplicateKeyError`. Moreover a duplicate
-value is not allowed. Defining a duplicate value will raise a `Ruby::Enum::Errors::DuplicateValueError`.
-The following declarations will both raise an exception:
+Defining duplicate enums raises `Ruby::Enum::Errors::DuplicateKeyError`.
 
 ```ruby
-  class Colors
-    include Ruby::Enum
+class OrderState
+  include Ruby::Enum
 
-    define :RED, "red"
-    define :RED, "my red" # will raise a DuplicateKeyError exception
-  end
+  define :CREATED, 'created'
+  define :CREATED, 'recreated' # raises DuplicateKeyError
+end
+```
 
-  # The following will raise a DuplicateValueError
-  class Colors
-    include Ruby::Enum
+Defining a duplicate value raises `Ruby::Enum::Errors::DuplicateValueError`.
 
-    define :RED, 'red'
-    define :SOME, 'red' # Boom
-  end
+```ruby
+class OrderState
+  include Ruby::Enum
+
+  define :CREATED, 'created'
+  define :RECREATED, 'created' # raises DuplicateValueError
+end
 ```
 
-The `DuplicateValueError` exception is thrown to be consistent with the unique key constraint.
-Since keys are unique there is no way to map values to keys using `Colors.value('red')`
+The `DuplicateValueError` exception is raised to be consistent with the unique key constraint. Since keys are unique, there needs to be a way to map values to keys using `OrderState.value('created')`.
+
+### Inheritance
+
+When inheriting from a `Ruby::Enum` class, all defined enums in the parent class will be accessible in sub classes as well. Sub classes can also provide extra enums, as usual.
 
-### Inheritance behavior
+``` ruby
+class OrderState
+  include Ruby::Enum
+
+  define :CREATED, 'CREATED'
+  define :PAID, 'PAID'
+end
 
-Inheriting from a `Ruby::Enum` class, all defined enums in the parent class will be accessible in sub classes as well.
-Sub classes can also provide extra enums as usual.
+class ShippedOrderState < OrderState
+  define :PREPARED, 'PREPARED'
+  define :SHIPPED, 'SHIPPED'
+end
+```
+
+``` ruby
+ShippedOrderState::CREATED # 'CREATED'
+ShippedOrderState::PAID # 'PAID'
+ShippedOrderState::PREPARED # 'PREPARED'
+ShippedOrderState::SHIPPED # 'SHIPPED'
+```
+
+The `values` class method will enumerate the values from all base classes.
+
+``` ruby
+OrderState.values # ['CREATED', 'PAID']
+ShippedOrderState.values # ['CREATED', 'PAID', 'PREPARED', SHIPPED']
+```
 
 ## Contributing
 
-You're encouraged to contribute to this gem. See [CONTRIBUTING](CONTRIBUTING.md) for details.
+You're encouraged to contribute to ruby-enum. See [CONTRIBUTING](CONTRIBUTING.md) for details.
 
 ## Copyright and License
 
-Copyright (c) 2013-2020, Daniel Doubrovkine and [Contributors](CHANGELOG.md).
+Copyright (c) 2013-2021, Daniel Doubrovkine and [Contributors](CHANGELOG.md).
 
 This project is licensed under the [MIT License](LICENSE.md).
 
diff --git a/RELEASING.md b/RELEASING.md
index 62adee4..756915c 100644
--- a/RELEASING.md
+++ b/RELEASING.md
@@ -1,6 +1,6 @@
 # Releasing Ruby-Enum
 
-There're no hard rules about when to release ruby-enum. Release bug fixes frequently, features not so frequently and breaking API changes rarely.
+There are no hard rules about when to release ruby-enum. Release bug fixes frequently, features not so frequently and breaking API changes rarely.
 
 ### Release
 
@@ -13,15 +13,10 @@ rake
 
 Check that the last build succeeded in [Travis CI](https://travis-ci.org/dblock/ruby-enum) for all supported platforms.
 
-Increment the version, modify [lib/ruby-enum/version.rb](lib/ruby-enum/version.rb).
-
-*  Increment the third number if the release has bug fixes and/or very minor features, only (eg. change `0.2.1` to `0.2.2`).
-*  Increment the second number if the release contains major features or breaking API changes (eg. change `0.2.1` to `0.3.0`).
-
-Change "Next Release" in [CHANGELOG.md](CHANGELOG.md) to the new version.
+Add a date to this release in [CHANGELOG.md](CHANGELOG.md).
 
 ```
-### 0.2.2 (7/10/2015)
+### 0.2.2 (2015/7/10)
 ```
 
 Remove the line with "Your contribution here.", since there will be no more contributions to this release.
@@ -31,7 +26,6 @@ Commit your changes.
 ```
 git add README.md CHANGELOG.md lib/ruby-enum/version.rb
 git commit -m "Preparing for release, 0.2.2."
-git push origin master
 ```
 
 Release.
@@ -50,8 +44,7 @@ Pushed ruby-enum 0.2.2 to rubygems.org.
 Add the next release to [CHANGELOG.md](CHANGELOG.md).
 
 ```
-Next Release
-============
+### 0.2.3 (Next)
 
 * Your contribution here.
 ```
diff --git a/UPGRADING.md b/UPGRADING.md
new file mode 100644
index 0000000..1a25311
--- /dev/null
+++ b/UPGRADING.md
@@ -0,0 +1,44 @@
+# Upgrading Ruby::Enum
+
+## Upgrading to >= 0.9.0
+
+### Inheritance & `Ruby::Enum.values`
+
+This only applies to classes that inherit from another which is a `Ruby::Enum`.
+
+Prior to version `0.9.0`, the `values` class method would enumerate only the
+values defined in the class.
+
+As of version `0.9.0`, the `values` class method enumerates values defined in
+the entire class heirarchy, ancestors first.
+
+``` ruby
+class PrimaryColors
+  include Ruby::Enum
+
+  define :RED, 'RED'
+  define :GREEN, 'GREEN'
+  define :BLUE, 'BLUE'
+end
+
+class RainbowColors < PrimaryColors
+  define :ORANGE, 'ORANGE'
+  define :YELLOW, 'YELLOW'
+  define :INIDGO, 'INIDGO'
+  define :VIOLET, 'VIOLET'
+end
+```
+
+`gem 'ruby-enum', '< 0.9.0'`
+
+``` ruby
+RainbowColors.values # ['ORANGE', 'YELLOW', 'INIDGO', 'VIOLET']
+```
+
+`gem 'ruby-enum', '>= 0.9.0'`
+
+``` ruby
+RainbowColors.values # ['RED', 'ORANGE', 'YELLOW', 'GREEN', 'BLUE', 'INIDGO', 'VIOLET']
+```
+
+See [#29](https://github.com/dblock/ruby-enum/pull/29) for more information.
diff --git a/lib/ruby-enum/enum.rb b/lib/ruby-enum/enum.rb
index fccabf1..f7abb4c 100644
--- a/lib/ruby-enum/enum.rb
+++ b/lib/ruby-enum/enum.rb
@@ -22,7 +22,7 @@ module ClassMethods
       # === Parameters
       # [key] Enumerator key.
       # [value] Enumerator value.
-      def define(key, value)
+      def define(key, value = key)
         @_enum_hash ||= {}
         @_enums_by_value ||= {}
 
@@ -118,7 +118,13 @@ def keys
 
       # Returns all enum values.
       def values
-        @_enum_hash.values.map(&:value)
+        result = @_enum_hash.values.map(&:value)
+
+        if superclass < Ruby::Enum
+          superclass.values + result
+        else
+          result
+        end
       end
 
       # Iterate over all enumerated values.
diff --git a/lib/ruby-enum/errors/base.rb b/lib/ruby-enum/errors/base.rb
index 01daa10..c4a726c 100644
--- a/lib/ruby-enum/errors/base.rb
+++ b/lib/ruby-enum/errors/base.rb
@@ -39,7 +39,7 @@ def compose_message(key, attributes = {})
         #
         # Returns a localized error message string.
         def translate(key, options)
-          ::I18n.translate("#{BASE_KEY}.#{key}", { locale: :en }.merge(options)).strip
+          ::I18n.translate("#{BASE_KEY}.#{key}", **{ locale: :en }.merge(options)).strip
         end
 
         # Create the problem.
diff --git a/lib/ruby-enum/version.rb b/lib/ruby-enum/version.rb
index ef51c17..1a3c94b 100644
--- a/lib/ruby-enum/version.rb
+++ b/lib/ruby-enum/version.rb
@@ -2,6 +2,6 @@
 
 module Ruby
   module Enum
-    VERSION = '0.8.0'
+    VERSION = '0.9.0'
   end
 end
diff --git a/spec/ruby-enum/enum_spec.rb b/spec/ruby-enum/enum_spec.rb
index 2bca1d9..6a7e560 100644
--- a/spec/ruby-enum/enum_spec.rb
+++ b/spec/ruby-enum/enum_spec.rb
@@ -187,6 +187,35 @@ class EmptyEnums
         expect(subject::ORANGE).to eq 'orange'
         expect(subject::PINK).to eq 'pink'
       end
+
+      describe '#values' do
+        subject { SecondSubclass.values }
+
+        it 'contains the values from all of the parent classes' do
+          expect(subject).to eq(%w[red green orange pink])
+        end
+      end
+    end
+
+    describe '#values' do
+      subject { FirstSubclass.values }
+
+      it 'contains the values from the parent class' do
+        expect(subject).to eq(%w[red green orange])
+      end
+    end
+  end
+
+  describe 'default value' do
+    class Default
+      include Ruby::Enum
+      define :KEY
+    end
+
+    subject { Default::KEY }
+
+    it 'equals the key' do
+      expect(subject).to eq(:KEY)
     end
   end
 
@@ -195,17 +224,25 @@ class States
       include Ruby::Enum
       define :created, 'Created'
       define :published, 'Published'
+      define :undefined
     end
     subject { States }
     it 'behaves like an enum' do
       expect(subject.created).to eq 'Created'
       expect(subject.published).to eq 'Published'
+      expect(subject.undefined).to eq :undefined
 
       expect(subject.key?(:created)).to be true
       expect(subject.key('Created')).to eq :created
 
       expect(subject.value?('Created')).to be true
       expect(subject.value(:created)).to eq 'Created'
+
+      expect(subject.key?(:undefined)).to be true
+      expect(subject.key(:undefined)).to eq :undefined
+
+      expect(subject.value?(:undefined)).to be true
+      expect(subject.value(:undefined)).to eq :undefined
     end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 1be2c76..38a174f 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,6 +3,10 @@
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 
 require 'rubygems'
+
+require 'simplecov'
+SimpleCov.start
+
 require 'rspec'
 require 'ruby-enum'