CODEWITHSUNDEEP
ruby-on-railsrubyrspec
JGutierrezC
JGutierrezC

Reputation: 4523

What is the meaning of "subject {page}" in Rspec and Ruby Language?

I'm reading the Ruby on Rails Tutorial", and on a page regarding to Rspec tests, there is this line:

subject {page}

We can omit the word from, for example:

it { page.should have_content('Help') }

What is subject? What is page?

Also, why is it declared subject{} and it{}? I saw that the braces ("{}"), are used when you are declaring a hash like:

user = {name: 'Jhon', lastName: 'Smith'}

Upvotes: 1

Views: 1754

Answers (2)

Andrei
Andrei

Reputation: 486

I hope this code can make it more clear:

Say you have a class:

class A
  def initialize(m, n)
    @m = m
    @n = n
  end

  def m
    @m
  end

  def n
    @n
  end
end

Than to test that method m returns the correct value you can use this code with subject:

subject { A.new("lorem", "ipsum") }
specify { subject.m.should == "lorem" }
specify { subject.n.should == "ipsum" }

In the example above subject will be the object that you created in subject { A.new("lorem", "ipsum") }.

Or you can use code like this to make the rspec examples shorter:

subject { A.new("lorem", "ipsum") }
its(:n) { should == "lorem" }
its(:m) { should == "ipsum" }

And the page in your post was just an object which was created somewhere else in the code of the test.

Upvotes: 2

Chris Cashwell
Chris Cashwell

Reputation: 22859

subject is an rspec method that takes a block which will be the implicit topic of your assertions. page refers to (probably) Capybara's page object, which is available in rspec tests using Capybara where you have done something like visit('/some/url').

Upvotes: 4

Related Questions