RSpec Rails.logger block test

my_stuff.rb

# frozen_string_literal: true

class MyStuff
  OOPS = 'Oops'
  
  def self.call
    Rails.logger.warn { OOPS }
  end
end

my_stuff_spec.rb

# frozen_string_literal: true

RSpec.describe MyStuff do
  let(:result) { described_class.call }

  before do
    allow(Rails.logger).to receive(:warn)
  
    result
  end
  
  it 'logs a warning' do
    expect(Rails.logger).to have_received(:warn) do |&block|
      expect(block.call).to eq(MyStuff::OOPS)
    end
  end
end