Ruby on rails rspec有问题，期待改变

我正在使用rspec测试一个Ruby终端应用程序。我似乎不知道如何测试散列中的更改

一般来说，我仍在努力对测试进行思考，所以很可能我对测试的很多方面都有误解

我试图测试，当一个费用被添加到帐户实例中，但费用超过了帐户限制时。账户上的余额不变

class Account
  def apply_charge(card_holder_name, charge)
    charge       = int_dollar_input(charge)
    account      = find_account_by_card_holder(card_holder_name) 
    temp_balance = account[:balance] + charge

    account[:balance] = account[:balance] + charge if temp_balance < account[:limit]
  end
end

describe "Adding a charge to an account" do
  context "GIVEN a charge amount that exceeds the account limit" do

    let(:account)     { subject.add_account("William", 5454545454545454,'$1000') }

    it "will do nothing" do
      expect(subject.apply_charge('William', '$1200')).
        to_not change {account[:balance]} 
    end
  end
end

1） 向帐户添加费用的帐户，该帐户的费用金额为 超过帐户限制将不起任何作用 失败/错误： 预期（受试者申请费用（'William'，'1200'））。 不更改{帐户[：余额]}

   expected `account[:balance]` not to have changed, but was not given a block
 # ./spec/account_spec.rb:46:in `block (4 levels) in <top (required)>'

应为'account[：balance]`未更改，但未被给予阻止
#./spec/account_spec.rb:46:in'block（4层）in'

---

Expect需要在一个块中：

Expect{subject.apply_charge（'William'，'1200'）}.to….

Expect需要在一个块中：

Expect{subject.apply_charge（'William'，'1200'）}.to….

   expected `account[:balance]` not to have changed, but was not given a block
 # ./spec/account_spec.rb:46:in `block (4 levels) in <top (required)>'