thoughtbot--shoulda-matchers/README.md

# Shoulda Matchers [![Gem Version][version-badge]][rubygems] [![Build Status][travis-badge]][travis] [![Total Downloads][downloads-total]][rubygems] [![Downloads][downloads-badge]][rubygems]

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[travis]: https://travis-ci.org/thoughtbot/shoulda-matchers
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[![shoulda-matchers][logo]][website]

[logo]: https://matchers.shoulda.io/images/shoulda-matchers-logo.png
[website]: https://matchers.shoulda.io/

Shoulda Matchers provides RSpec- and Minitest-compatible one-liners to test
common Rails functionality that, if written by hand, would be much longer, more
complex, and error-prone.

## Quick links

📖 **[Read the documentation for the latest version][rubydocs].**  
📢 **[See what's changed in recent versions][changelog].**

[rubydocs]: https://matchers.shoulda.io/docs
[changelog]: CHANGELOG.md

## Table of contents

* [Getting started](#getting-started)
   * [RSpec](#rspec)
   * [Minitest](#minitest)
* [Usage](#usage)
  * [On the subject of `subject`](#on-the-subject-of-subject)
  * [Availability of RSpec matchers in example groups](#availability-of-rspec-matchers-in-example-groups)
  * [`should` vs `is_expected.to`](#should-vs-is_expectedto)
* [Matchers](#matchers)
   * [ActiveModel matchers](#activemodel-matchers)
   * [ActiveRecord matchers](#activerecord-matchers)
   * [ActionController matchers](#actioncontroller-matchers)
   * [Independent matchers](#independent-matchers)
* [Extensions](#extensions)
* [Contributing](#contributing)
* [Compatibility](#compatibility)
* [Versioning](#versioning)
* [Team](#team)
* [Copyright/License](#copyright-license)
* [About thoughtbot](#about-thoughtbot)

## Getting started

### RSpec

Start by including `shoulda-matchers` in your Gemfile:

```ruby
group :test do
  gem 'shoulda-matchers', '~> 4.0'
end
```

Then run `bundle install`.

Now you need to configure the gem by telling it:

* which matchers you want to use in your tests
* that you're using RSpec so that it can make those matchers available in
  your example groups

#### Rails apps

If you're working on a Rails app, simply place this at the bottom of
`spec/rails_helper.rb` (or in a support file if you so choose):

```ruby
Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :rspec
    with.library :rails
  end
end
```

#### Non-Rails apps

If you're not working on a Rails app, but you still make use of ActiveRecord or
ActiveModel in your project, you can still use this gem too! In that case,
you'll want to place the following configuration at the bottom of
`spec/spec_helper.rb`:

```ruby
Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :rspec

    # Keep as many of these lines as are necessary:
    with.library :active_record
    with.library :active_model
  end
end
```

### Minitest

If you're using our umbrella gem [Shoulda], then make sure that you're using the
latest version:

```ruby
group :test do
  gem 'shoulda', '~> 4.0'
end
```

[Shoulda]: https://github.com/thoughtbot/shoulda

Otherwise, add `shoulda-matchers` to your Gemfile:

```ruby
group :test do
  gem 'shoulda-matchers', '~> 4.0'
end
```

Then run `bundle install`.

Now you need to configure the gem by telling it:

* which matchers you want to use in your tests
* that you're using Minitest so that it can make those matchers available in
  your test case classes

#### Rails apps

If you're working on a Rails app, simply place this at the bottom of
`test/test_helper.rb`:

```ruby
Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :minitest
    with.library :rails
  end
end
```

#### Non-Rails apps

If you're not working on a Rails app, but you still make use of ActiveRecord or
ActiveModel in your project, you can still use this gem too! In that case,
you'll want to place the following configuration at the bottom of
`test/test_helper.rb`:

```ruby
Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :minitest

    # Keep as many of these lines as are necessary:
    with.library :active_record
    with.library :active_model
  end
end
```

## Usage

Most of the matchers provided by this gem are useful in a Rails context, and as
such, can be used for different parts of a Rails app:

* [database models backed by ActiveRecord](#activemodel-matchers)
* [non-database models, form objects, etc. backed by
  ActiveModel](#activerecord-matchers)
* [controllers](#actioncontroller-matchers)
* [routes](#routing-matchers) (RSpec only)
* [Rails-specific features like `delegate`](#independent-matchers)

As the name of the gem indicates, most matchers are designed to be used in
"one-liner" form using the `should` macro, a special directive available in both
RSpec and [Shoulda]. For instance, a model test case may look something like:

``` ruby
# RSpec
RSpec.describe MenuItem, type: :model do
  describe 'associations' do
    it { should belong_to(:category).class_name('MenuCategory') }
  end

  describe 'validations' do
    it { should validate_presence_of(:name) }
    it { should validate_uniqueness_of(:name).scoped_to(:category_id) }
  end
end

# Minitest (Shoulda)
class MenuItemTest < ActiveSupport::TestCase
  context 'associations' do
    should belong_to(:category).class_name('MenuCategory')
  end

  context 'validations' do
    should validate_presence_of(:name)
    should validate_uniqueness_of(:name).scoped_to(:category_id)
  end
end
```

[See below](#matchers) for the full set of matchers that you can use.

### On the subject of `subject`

For both RSpec and Shoulda, the **subject** is an implicit reference to the
object under test, and through the use of `should` as demonstrated above, all of
the matchers make use of `subject` internally when they are run. A `subject` is
always set automatically by your test framework in any given test case; however,
in certain cases it can be advantageous to override it. For instance, when
testing validations in a model, it is customary to provide a valid model instead
of a fresh one:

``` ruby
# RSpec
RSpec.describe Post, type: :model do
  describe 'validations' do
    # Here we're using FactoryBot, but you could use anything
    subject { build(:post) }

    it { should validate_presence_of(:title) }
  end
end

# Minitest (Shoulda)
class PostTest < ActiveSupport::TestCase
  context 'validations' do
    subject { build(:post) }

    should validate_presence_of(:title)
  end
end
```

When overriding the subject in this manner, then, it's important to provide the
correct object. **When in doubt, provide an instance of the class under test.**
This is particularly necessary for controller tests, where it is easy to
accidentally write something like:

``` ruby
RSpec.describe PostsController, type: :controller do
  describe 'GET #index' do
    subject { get :index }

    # This may work...
    it { should have_http_status(:success) }
    # ...but this will not!
    it { should permit(:title, :body).for(:post) }
  end
end
```

In this case, you would want to use `before` rather than `subject`:

``` ruby
RSpec.describe PostsController, type: :controller do
  describe 'GET #index' do
    before { get :index }

    # Notice that we have to assert have_http_status on the response here...
    it { expect(response).to have_http_status(:success) }
    # ...but we do not have to provide a subject for render_template
    it { should render_template('index') }
  end
end
```

### Availability of RSpec matchers in example groups

#### Rails projects

If you're using RSpec, then you're probably familiar with the concept of example
groups. Example groups can be assigned tags order to assign different behavior
to different kinds of example groups. This comes into play especially when using
`rspec-rails`, where, for instance, controller example groups, tagged with
`type: :controller`, are written differently than request example groups, tagged
with `type: :request`. This difference in writing style arises because
`rspec-rails` mixes different behavior and methods into controller example
groups vs. request example groups.

Relying on this behavior, Shoulda Matchers automatically makes certain matchers
available in certain kinds of example groups:

* ActiveRecord and ActiveModel matchers are available only in model example
  groups, i.e., those tagged with `type: :model` or in files located under
  `spec/models`.
* ActionController matchers are available only in controller example groups,
  i.e., those tagged with `type: :controller` or in files located under
  `spec/controllers`.
* The `route` matcher is available in routing example groups, i.e., those
  tagged with `type: :routing` or in files located under `spec/routing`.
* Independent matchers are available in all example groups.

As long as you're using Rails, you don't need to worry about these details —
everything should "just work".

#### Non-Rails projects

**What if you are using ActiveModel or ActiveRecord outside of Rails, however,
and you want to use model matchers in a certain example group?** Then you'll
need to manually include the module that holds those matchers into that example
group. For instance, you might have to say:

``` ruby
RSpec.describe MySpecialModel do
  include Shoulda::Matchers::ActiveModel
  include Shoulda::Matchers::ActiveRecord
end
```

If you have a lot of similar example groups in which you need to do this, then
you might find it more helpful to tag your example groups appropriately, then
instruct RSpec to mix these modules into any example groups that have that tag.
For instance, you could add this to your `rails_helper.rb`:

```ruby
RSpec.configure do |config|
  config.include(Shoulda::Matchers::ActiveModel, type: :model)
  config.include(Shoulda::Matchers::ActiveRecord, type: :model)
end
```

And from then on, you could say:

```ruby
RSpec.describe MySpecialModel, type: :model do
  # ...
end
```

### `should` vs `is_expected.to`

In this README and throughout the documentation, you'll notice that we use the
`should` form of RSpec's one-liner syntax over `is_expected.to`. Beside being
the namesake of the gem itself, this is our preferred syntax as it's short and
sweet. But if you prefer to use `is_expected.to`, you can do that too:

```ruby
RSpec.describe Person, type: :model do
  it { is_expected.to validate_presence_of(:name) }
end
```

## Matchers

Here is the full list of matchers that ship with this gem. If you need details
about any of them, make sure to [consult the documentation][rubydocs]!

### ActiveModel matchers

* **[allow_value](lib/shoulda/matchers/active_model/allow_value_matcher.rb)**
  tests that an attribute is valid or invalid if set to one or more values.
  *(Aliased as #allow_values.)*
* **[have_secure_password](lib/shoulda/matchers/active_model/have_secure_password_matcher.rb)**
  tests usage of `has_secure_password`.
* **[validate_absence_of](lib/shoulda/matchers/active_model/validate_absence_of_matcher.rb)**
  tests usage of `validates_absence_of`.
* **[validate_acceptance_of](lib/shoulda/matchers/active_model/validate_acceptance_of_matcher.rb)**
  tests usage of `validates_acceptance_of`.
* **[validate_confirmation_of](lib/shoulda/matchers/active_model/validate_confirmation_of_matcher.rb)**
  tests usage of `validates_confirmation_of`.
* **[validate_exclusion_of](lib/shoulda/matchers/active_model/validate_exclusion_of_matcher.rb)**
  tests usage of `validates_exclusion_of`.
* **[validate_inclusion_of](lib/shoulda/matchers/active_model/validate_inclusion_of_matcher.rb)**
  tests usage of `validates_inclusion_of`.
* **[validate_length_of](lib/shoulda/matchers/active_model/validate_length_of_matcher.rb)**
  tests usage of `validates_length_of`.
* **[validate_numericality_of](lib/shoulda/matchers/active_model/validate_numericality_of_matcher.rb)**
  tests usage of `validates_numericality_of`.
* **[validate_presence_of](lib/shoulda/matchers/active_model/validate_presence_of_matcher.rb)**
  tests usage of `validates_presence_of`.

### ActiveRecord matchers

* **[accept_nested_attributes_for](lib/shoulda/matchers/active_record/accept_nested_attributes_for_matcher.rb)**
  tests usage of the `accepts_nested_attributes_for` macro.
* **[belong_to](lib/shoulda/matchers/active_record/association_matcher.rb)**
  tests your `belongs_to` associations.
* **[define_enum_for](lib/shoulda/matchers/active_record/define_enum_for_matcher.rb)**
  tests usage of the `enum` macro.
* **[have_and_belong_to_many](lib/shoulda/matchers/active_record/association_matcher.rb#L827)**
  tests your `has_and_belongs_to_many` associations.
* **[have_db_column](lib/shoulda/matchers/active_record/have_db_column_matcher.rb)**
  tests that the table that backs your model has a specific column.
* **[have_db_index](lib/shoulda/matchers/active_record/have_db_index_matcher.rb)**
  tests that the table that backs your model has an index on a specific column.
* **[have_implicit_order_column](lib/shoulda/matchers/active_record/have_implicit_order_column.rb)**
  tests usage of `implicit_order_column`.
* **[have_many](lib/shoulda/matchers/active_record/association_matcher.rb#L328)**
  tests your `has_many` associations.
* **[have_many_attached](lib/shoulda/matchers/active_record/have_attached_matcher.rb)**
  tests your `has_many_attached` associations.
* **[have_one](lib/shoulda/matchers/active_record/association_matcher.rb#L598)**
  tests your `has_one` associations.
* **[have_one_attached](lib/shoulda/matchers/active_record/have_attached_matcher.rb)**
  tests your `has_one_attached` associations.
* **[have_readonly_attribute](lib/shoulda/matchers/active_record/have_readonly_attribute_matcher.rb)**
  tests usage of the `attr_readonly` macro.
* **[have_rich_text](lib/shoulda/matchers/active_record/have_rich_text_matcher.rb)**
  tests your `has_rich_text` associations.
* **[serialize](lib/shoulda/matchers/active_record/serialize_matcher.rb)** tests
  usage of the `serialize` macro.
* **[validate_uniqueness_of](lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb)**
  tests usage of `validates_uniqueness_of`.

### ActionController matchers

* **[filter_param](lib/shoulda/matchers/action_controller/filter_param_matcher.rb)**
  tests parameter filtering configuration.
* **[permit](lib/shoulda/matchers/action_controller/permit_matcher.rb)** tests
  that an action places a restriction on the `params` hash.
* **[redirect_to](lib/shoulda/matchers/action_controller/redirect_to_matcher.rb)**
  tests that an action redirects to a certain location.
* **[render_template](lib/shoulda/matchers/action_controller/render_template_matcher.rb)**
  tests that an action renders a template.
* **[render_with_layout](lib/shoulda/matchers/action_controller/render_with_layout_matcher.rb)**
  tests that an action is rendered with a certain layout.
* **[rescue_from](lib/shoulda/matchers/action_controller/rescue_from_matcher.rb)**
  tests usage of the `rescue_from` macro.
* **[respond_with](lib/shoulda/matchers/action_controller/respond_with_matcher.rb)**
  tests that an action responds with a certain status code.
* **[route](lib/shoulda/matchers/action_controller/route_matcher.rb)** tests
  your routes.
* **[set_session](lib/shoulda/matchers/action_controller/set_session_matcher.rb)**
  makes assertions on the `session` hash.
* **[set_flash](lib/shoulda/matchers/action_controller/set_flash_matcher.rb)**
  makes assertions on the `flash` hash.
* **[use_after_action](lib/shoulda/matchers/action_controller/callback_matcher.rb#L79)**
  tests that an `after_action` callback is defined in your controller.
* **[use_around_action](lib/shoulda/matchers/action_controller/callback_matcher.rb#L129)**
  tests that an `around_action` callback is defined in your controller.
* **[use_before_action](lib/shoulda/matchers/action_controller/callback_matcher.rb#L54)**
  tests that a `before_action` callback is defined in your controller.

### Routing matchers

* **[route](lib/shoulda/matchers/action_controller/route_matcher.rb)** tests
  your routes.

### Independent matchers

* **[delegate_method](lib/shoulda/matchers/independent/delegate_method_matcher.rb)**
  tests that an object forwards messages to other, internal objects by way of
  delegation.

## Extensions

Over time our community has created extensions to Shoulda Matchers. If you've
created something that you want to share, please [let us know][new-issue]!

* **[shoulda-matchers-cucumber]** – Adds support for using Shoulda Matchers in
  Cucumber tests.

[new-issue]: https://github.com/thoughtbot/shoulda-matchers/issues/new
[shoulda-matchers-cucumber]: https://github.com/majioa/shoulda-matchers-cucumber

## Contributing

Have a fix for a problem you've been running into or an idea for a new feature
you think would be useful? Take a look at the [Contributing
document](CONTRIBUTING.md) for instructions on setting up the repo on your
machine, understanding the codebase, and creating a good pull request.

## Compatibility

Shoulda Matchers is [tested][travis] and supported against Ruby 2.4+, Rails
4.2+, RSpec 3.x, and Minitest 5.x.

For Ruby < 2.4 and Rails < 4.1 compatibility, please use [v3.1.3][v3.1.3].

[v3.1.3]: https://github.com/thoughtbot/shoulda-matchers/tree/v3.1.3

## Versioning

Shoulda Matchers follows Semantic Versioning 2.0 as defined at
<https://semver.org>.

## Team

Shoulda Matchers is maintained by [Elliot Winkler][mcmire] and [Gui
Albuk][guialbuk].

[mcmire]: https://github.com/mcmire
[guialbuk]: https://github.com/guialbuk

## Copyright/License

Shoulda Matchers is copyright © 2006-2021 Tammer Saleh and [thoughtbot,
inc][thoughtbot-website]. It is free and opensource software and may be
redistributed under the terms specified in the [LICENSE](LICENSE) file.

[thoughtbot-website]: https://thoughtbot.com

## About thoughtbot

![thoughtbot][thoughtbot-logo]

[thoughtbot-logo]: https://presskit.thoughtbot.com/images/thoughtbot-logo-for-readmes.svg

The names and logos for thoughtbot are trademarks of thoughtbot, inc.

We are passionate about open source software. See [our other
projects][community]. We are [available for hire][hire].

[community]: https://thoughtbot.com/community?utm_source=github
[hire]: https://thoughtbot.com?utm_source=github