test.rb

class GreetUser
  include Interactor
  
  def call
    puts "Hello, #{context.user.name}"
  end
end

class SaveUser
  include Interactor
  
  def call
    context.user.save
    GreetUser.call(user: context.user)
  end
end

describe GreetUser do
   it 'prints welcome message'
end

describe SaveUser
  it 'saves user'

  it 'greets user' do
    user = User.new
    expect(GreetUser).to receive(:call).with(user: user)
    SaveUser(user: user)
  end
end