test4.rb

class Klass
  def a(b)
    p "Hello"
  end

  def c
    a(1)
    a(2)
  end
end

describe Klass do
  subject { Klass.new }
  
  before {
    allow(subject).to receive(:a)
    subject.c
  }

  it {
    should have_received(:a).with(1).once.ordered
    should have_received(:a).with(2).once.ordered
  }
end