# Mâché
[](https://travis-ci.org/nullobject/mache)
Mâché (pronounced "mash-ay") is a tool that helps you to write cleaner and more
expressive acceptance tests for your Ruby web applications using page objects.
## Table of contents
* [Mâché](#mâché)
* [Table of contents](#table-of-contents)
* [What is a page object?](#what-is-a-page-object)
* [Getting started](#getting-started)
* [Elements](#elements)
* [Components](#components)
* [Helpers](#helpers)
* [Example](#example)
* [API documentation](#api-documentation)
* [Contributing](#contributing)
* [License](#license)
## What is a page object?
A [page object](https://martinfowler.com/bliki/PageObject.html) is a data
structure that provides an interface to your web application for the purposes
of test automation. For example, it could represent a single HTML page, or
perhaps even a fragment of HTML on a page.
From [Martin Fowler](https://martinfowler.com/bliki/PageObject.html):
> A page object wraps an HTML page, or fragment, with an application-specific
> API, allowing you to manipulate page elements without digging around in the
> HTML.
[Capybara](https://github.com/teamcapybara/capybara) can get us part of the way
there. It allows us to work with an API rather than manipulating the HTML
directly, but what it provides isn't an *application specific* API. It gives us
low-level API methods like `find`, `fill_in`, and `click_button`, but it
doesn't provide us with high-level methods to do things like "sign in to the
app" or "click the Dashboard item in the navigation bar".
This is where page objects come in. Using Mâché we can for instance define a
page object class called `SignInPage` and use it any time we want to automate
authenticating with our app. It could handle visiting the sign in page,
entering the user's credentials, and clicking the "Sign in" button.
## Getting started
Let's dive straight in and take a look at an example. Consider the following
HTML fragment for the welcome page in our app:
```html
Welcome
lorem ipsum
lorem ipsum
```
To define a `WelcomePage` page object class to wrap this HTML page, we extend
the `Mache::Page` class. The only method our class needs to provide is `path`,
this tells Mâché where to go when we want to visit the page:
```ruby
require "mache"
class WelcomePage < Mache::Page
def path
"/welcome"
end
end
```
We can visit our welcome page using our page object:
```ruby
page = WelcomePage.visit
page.current? # true
```
Mâché also handily exposes the Capybara API on our page object:
```ruby
page.find("main").text # "lorem ipsum"
```
### Elements
To make our page object more useful, we can define an element on our page
object class using the `element` macro. An element is simply an HTML element
that we expect to find on the page using a CSS selector.
Let's define a `main` element to represent the main section of our HTML page:
```ruby
require "mache"
class WelcomePage < Mache::Page
element :main, "main"
def path
"/welcome"
end
end
```
We can query the `main` element as an attribute of our page object:
```ruby
page.main.text # "lorem ipsum"
```
### Components
For elements that can be shared across any number of page object classes it may
be useful to define a reusable component by extending the `Mache::Node` class.
A component can contain any number of elements (or even other components).
Let's define a `Header` component to represent the header of our HTML page:
```ruby
require "mache"
class Header < Mache::Node
element :title, "h1"
end
```
We can mount the `Header` component in our page object class at a given CSS
selector using the `component` macro:
```ruby
require "mache"
class WelcomePage < Mache::Page
component :header, Header, "header"
element :main, "main"
def path
"/welcome"
end
end
```
Querying a component of our page object is much the same as with an element:
```ruby
page.header.title.text # "Welcome"
```
### Helpers
Mâché provides helpers for testing Rails apps.
#### Flash
The `Flash` helper provides methods for testing flash messages. First define a
flash in your page object class:
```ruby
require "mache"
require "mache/helpers/rails"
class WelcomePage < Mache::Page
include Mache::Helpers::Rails::Flash
flash "#flash"
end
```
Then you can query the flash on your page object:
```ruby
page.has_notice_message?("Welcome to the app")
page.has_alert_message?("A horrible error occurred")
```
#### Routes
The `Routes` helper mixes the Rails URL helpers into your page object class.
This allows you to use the `*_path` and `*_url` methods as you normally would
in your Rails.
```ruby
require "mache"
require "mache/helpers/rails"
class WelcomePage < Mache::Page
include Mache::Helpers::Rails::Routes
def path
welcome_path
end
end
```
## Example
Let's look at an example of an acceptance test for our `WelcomePage`. Note that
the `Header`, `NavItem`, and `Nav` components can be reused in any other page
object classes we may define later for our web application.
```ruby
require "mache"
require "mache/helpers/rails"
class Header < Mache::Node
element :title, "h1"
end
class NavItem < Mache::Node
def selected?
node[:class].include?("selected")
end
end
class Nav < Mache::Node
components :items, NavItem, "a"
def selected_item
items.find(&:selected?)
end
end
class WelcomePage < Mache::Page
include Mache::Helpers::Rails::Flash
include Mache::Helpers::Rails::Routes
component :header, Header, "header"
component :nav, Nav, "nav"
element :main, "main"
flash "#flash"
def path
welcome_path
end
end
feature "Welcome page" do
let(:home_page) { WelcomePage.visit }
scenario "A user visits the welcome page" do
expect(home_page).to be_current
# header
expect(home_page).to have_header
expect(home_page.header.title).to eq("Welcome")
# nav
expect(home_page).to have_nav
expect(home_page.nav).to have_items
expect(home_page.nav.items.count).to be(3)
expect(home_page.nav.items[0].text).to eq("foo")
expect(home_page.nav.items[1].text).to eq("bar")
expect(home_page.nav.items[2].text).to eq("baz")
expect(home_page.nav.selected_item).to eq("foo")
# main
expect(home_page.main.text).to eq("lorem ipsum")
# flash
expect(home_page).to have_flash
expect(home_page).to have_notice_message("lorem ipsum")
end
end
```
## API documentation
Read the [API documentation](http://www.rubydoc.info/gems/mache) on RubyDoc.
## Contributing
Pull requests are welcome. Please ensure that you run the tests before
submitting your PR:
```
> bundle exec rake
```
## License
Mâché is licensed under the [MIT License](/LICENSE).