useless_method_definition_spec.rb

# frozen_string_literal: true

RSpec.describe RuboCop::Cop::Lint::UselessMethodDefinition, :config do
  subject(:cop) { described_class.new(config) }

  let(:cop_config) do
    { 'AllowComments' => true }
  end

  it 'does not register an offense for empty constructor' do
    expect_no_offenses(<<~RUBY)
      class Foo
        def initialize(arg1, arg2)
        end
      end
    RUBY
  end

  it 'does not register an offense for constructor with only comments' do
    expect_no_offenses(<<~RUBY)
      def initialize(arg)
        # Comment.
      end
    RUBY
  end

  it 'does not register an offense for constructor containing additional code to `super`' do
    expect_no_offenses(<<~RUBY)
      def initialize(arg)
        super
        do_something
      end
    RUBY
  end

  it 'does not register an offense for empty class level `initialize` method' do
    expect_no_offenses(<<~RUBY)
      def self.initialize
      end
    RUBY
  end

  it 'registers an offense and corrects for method containing only `super` call' do
    expect_offense(<<~RUBY)
      class Foo
        def useful_instance_method
          do_something
        end

        def instance_method
        ^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
          super
        end

        def instance_method_with_args(arg)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
          super(arg)
        end

        def self.useful_class_method
          do_something
        end

        def self.class_method
        ^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
          super
        end

        def self.class_method_with_args(arg)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
          super(arg)
        end

        class << self
          def self.other_useful_class_method
            do_something
          end

          def other_class_method
          ^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
            super
          end

          def other_class_method_with_parens
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
            super()
          end

          def other_class_method_with_args(arg)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
            super(arg)
          end
        end
      end
    RUBY

    expect_correction(<<~RUBY)
      class Foo
        def useful_instance_method
          do_something
        end

       #{trailing_whitespace}

       #{trailing_whitespace}

        def self.useful_class_method
          do_something
        end

       #{trailing_whitespace}

       #{trailing_whitespace}

        class << self
          def self.other_useful_class_method
            do_something
          end

         #{trailing_whitespace}

         #{trailing_whitespace}

         #{trailing_whitespace}
        end
      end
    RUBY
  end

  it 'does not register an offense for method containing additional code to `super`' do
    expect_no_offenses(<<~RUBY)
      def method
        super
        do_something
      end
    RUBY
  end

  it 'does not register an offense when `super` arguments differ from method arguments' do
    expect_no_offenses(<<~RUBY)
      def method1(foo)
        super(bar)
      end

      def method2(foo, bar)
        super(bar, foo)
      end

      def method3(foo, bar)
        super()
      end
    RUBY
  end

  it 'does not register an offense when method definition contains optional argument' do
    expect_no_offenses(<<~RUBY)
      def method(x = 1)
        super
      end
    RUBY
  end

  it 'does not register an offense when method definition contains optional keyword argument' do
    expect_no_offenses(<<~RUBY)
      def method(x: 1)
        super
      end
    RUBY
  end

  it 'does not register an offense when non-constructor contains only comments' do
    expect_no_offenses(<<~RUBY)
      def non_constructor
        # Comment.
      end
    RUBY
  end
end