RSpec shared_example/matcher

Question 1

How to create and use shared_example?

Answer 1

shared_examples 'testable' do
    it 'works' do
      expect(true).to be true
    end
  end

it_behaves_like ‘testable’

Question 2

How to run shared examples? ( 2 way )

Answer 2

it_behaves_like ‘testable’

include_examples ‘testable’

Question 3

How to rewrite let() inside shared examples?

Answer 3

# send new let inside the block
  shared_examples 'testable' do
    let(:sample) { 'Sample' }

it 'works' do
  expect(sample).to eq 'Sample From Shared Example Block'
end   end

it_behaves_like ‘testable’ do
let(:sample) { ‘Sample From Shared Example Block’ }
end

Question 4

How to define custom matcher?

Answer 4

RSpec::Matchers.define :be_length_equal_two do
    match do |actual|
      actual.size == 2
    end
  end

it ‘checks object attributes’ do
expect(‘ss’).to be_length_equal_two
end

Question 5

How to define custom matcher with an argument?

Answer 5

RSpec::Matchers.define :be_length_equal_to do |expected|
    match do |actual|
      actual.size == expected
    end
  end

it ‘checks object attributes’ do
expect(‘ss’).to be_length_equal_to(2)
end