Class: RuboCop::Cop::RSpec::NamedSubject

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/rspec/named_subject.rb

Overview

Checks for explicitly referenced test subjects.

RSpec lets you declare an “implicit subject” using `subject { … }` which allows for tests like `it { is_expected.to be_valid }`. If you need to reference your test subject you should explicitly name it using `subject(:your_subject_name) { … }`. Your test subjects should be the most important object in your tests so they deserve a descriptive name.

This cop can be configured in your configuration using the `IgnoreSharedExamples` which will not report offenses for implicit subjects in shared example groups.

Examples:

# bad
RSpec.describe User do
  subject { described_class.new }

  it 'is valid' do
    expect(subject.valid?).to be(true)
  end
end

# good
RSpec.describe Foo do
  subject(:user) { described_class.new }

  it 'is valid' do
    expect(user.valid?).to be(true)
  end
end

# also good
RSpec.describe Foo do
  subject(:user) { described_class.new }

  it { is_expected.to be_valid }
end

Constant Summary collapse

MSG =
'Name your test subject if you need to reference it explicitly.'

Instance Method Summary collapse

Methods inherited from Base

inherited, #on_new_investigation

Methods included from RSpec::Language::NodePattern

#block_pattern, #send_pattern

Methods included from RSpec::Language

#example?, #example_group?, #example_group_with_body?, #hook?, #include?, #let?, #rspec?, #shared_group?, #spec_group?, #subject?

Instance Method Details

#example_or_hook_block?(node) ⇒ Object


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# File 'lib/rubocop/cop/rspec/named_subject.rb', line 48

def_node_matcher :example_or_hook_block?,
block_pattern('{#Examples.all #Hooks.all}')

#ignored_shared_example?(node) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/rubocop/cop/rspec/named_subject.rb', line 68

def ignored_shared_example?(node)
  cop_config['IgnoreSharedExamples'] &&
    node.each_ancestor(:block).any?(&method(:shared_example?))
end

#on_block(node) ⇒ Object


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# File 'lib/rubocop/cop/rspec/named_subject.rb', line 58

def on_block(node)
  if !example_or_hook_block?(node) || ignored_shared_example?(node)
    return
  end

  subject_usage(node) do |subject_node|
    add_offense(subject_node.loc.selector)
  end
end

#shared_example?(node) ⇒ Object


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# File 'lib/rubocop/cop/rspec/named_subject.rb', line 52

def_node_matcher :shared_example?,
block_pattern('#SharedGroups.examples')

#subject_usage(node) ⇒ Object


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# File 'lib/rubocop/cop/rspec/named_subject.rb', line 56

def_node_search :subject_usage, '$(send nil? :subject)'