gistfile1.rb

module AuthRequestHelper
  def http_auth_as(username, password, &block)
    @env = {} unless @env
    old_auth = @env['HTTP_AUTHORIZATION']
    @env['HTTP_AUTHORIZATION'] = ActionController::HttpAuthentication::Basic.encode_credentials(username, password)
    yield block
    @env['HTTP_AUTHORIZATION'] = old_auth
  end
  
  def auth_get(url, params={}, env={})
    get url, params, @env.merge(env)
  end

  def auth_post(url, params={}, env={})
    post url, params, @env.merge(env)
  end

  def auth_put(url, params={}, env={})
    put url, params, @env.merge(env)
  end

  def auth_patch(url, params={}, env={})
    patch url, params, @env.merge(env)
  end

  def auth_delete(url, params={}, env={})
    delete url, params, @env.merge(env)
  end
end

spec1.rb

RSpec.describe 'Clients API' do
  include AuthRequestHelper

  context 'GET index' do
    it 'lists all clients for admin' do
      http_auth_as 'admin', 'secret' do
        auth_get '/clients.json'
        expect(response.status).to eq 200
      end
    end
  end
end

spec2.rb

# Alternatively, you could just do an around filter so all your specs are authed by the same user

RSpec.describe 'Clients API' do
  include AuthRequestHelper

  around :each do |example|
    http_auth_as 'admin', 'secret' do
      example.run
    end
  end

  context 'GET index' do
    it 'lists all clients for admin' do
      auth_get '/clients.json'
      expect(response.status).to eq 200
    end
  end
end