**Capybara** is a web-based automation framework that creates certain functional tests in order to simulate how a user may interact with an application. It is a library used on top of a web-based driver that writes the code in Ruby. This Ruby library has an advantage as it interacts with applications​ from a Rack level.

# RSpec matchers
**RSpec matchers** are just RSpec-style aliases for methods that already exist in Capybara’s `Node::Matchers` class. They are basically built-in functions of the `Matchers` class used for the testing and debugging of data. The terminology makes use of the `should` keyword. Let's look at a few examples:

**have_content**:
The `have_content` matcher checks if the article has specific content, as typed in the brackets:
```
page.should have_content("Hello Word") 
```
**have_selector**:
The `have_selector` matcher checks if the article of a specific title has specific tags, e.g., h2, h1, etc. 
```
page.should have_selector("h1#article_title", text: article.title)
```
Similarly, the opposite of any matcher is done through the `should_not` keyword:
```
page.should_not have_content("Hello Word") 
```
> For details on all the RSpec matchers, [click here](https://rubydoc.info/github/jnicklas/capybara/master/Capybara/RSpecMatchers).

# Code
Say you have a list and you want to check whether or not the list contains a specific element. If it does not contain that element, the test should fail, but if it does, the could will not fail. Let's implement this:

1. First, we need to define the matcher that we will use. In our case, the matcher is defined as `contain`.

2. Define the array.

3. Use the `should` keyword to find out if the element is part of the list or not. 

Look at the code below, it's written in Ruby:





Spec::Matcher.define :contain do |element|
    match do |container|
        container.include? element
    end
end

describe Array do
    it "Check element" do
        arr=[1,2,3,"nine", "hello"]
        arr.should contain "nine"
    end
end


Capybara -RSpec Matchers 

Capybara is a Ruby-based web automation framework. RSpec matchers are built-in Capybara methods for testing and debugging, using the should keyword for assertions.