one_liner_syntax.feature

Feature: One-liner syntax

  RSpec supports a one-liner syntax for setting an expectation
  on the `subject`. RSpec will give the examples a doc string
  that is auto-generated from the matcher used in the example.
  This is designed specifically to help avoid duplication in
  situations where the doc string and the matcher used in the
  example mirror each other exactly. When used excessively,
  it can produce documentation output that does not read well
  or contribute to understanding the object you are describing.

  This comes in two flavors:

    * `is_expected` is defined simply as `expect(subject)` and is
      designed for when you are using rspec-expectations with its
      newer expect-based syntax.
    * `should` was designed back when rspec-expectations only had
      a should-based syntax. However, it continues to be available
      and work even if the `:should` syntax is disabled (since that
      merely removes `Object#should` but this is
      `RSpec::Core::ExampleGroup#should`).

  Note: this feature is only available when using rspec-expectations.

  Scenario: implicit subject
    Given a file named "example_spec.rb" with:
      """ruby
      describe Array do
        describe "when first created" do
          # Rather than:
          # it "should be empty" do
          #   subject.should be_empty
          # end

          it { should be_empty }
          # or
          it { is_expected.to be_empty }
        end
      end
      """
    When I run `rspec example_spec.rb --format doc`
    Then the examples should all pass
     And the output should contain:
       """
       Array
         when first created
           should be empty
           should be empty
       """

  Scenario: explicit subject
    Given a file named "example_spec.rb" with:
      """ruby
      describe Array do
        describe "with 3 items" do
          subject { [1,2,3] }
          it { should_not be_empty }
          # or
          it { is_expected.not_to be_empty }
        end
      end
      """
    When I run `rspec example_spec.rb --format doc`
    Then the examples should all pass
     And the output should contain:
       """
       Array
         with 3 items
           should not be empty
           should not be empty
       """