双重和间谍有什么区别？

Question

我正在阅读关于spies的内容，我看不出它之间存在差异：

  File "/usr/lib/python2.7/dist-packages/django/forms/models.py", line 294, in __new__
    raise FieldError(message)
django.core.exceptions.FieldError: Unknown field(s) (is_admin) specified for Freelancer

而且：

RSpec.describe "have_received" do
  it "passes when the message has been received" do
    invitation = spy('invitation', deliver: "ok")
    invitation.deliver
    expect(invitation).to have_received(:deliver)
  end
end

两个例子都没有问题。我使用RSpec.describe "have_received" do it "passes when the message has been received" do invitation = double('invitation', deliver: "ok") invitation.deliver expect(invitation).to have_received(:deliver) end end

看不出任何优势

Answer 1

正如@max在评论中所说，区别在于我可以使用spy而不说deliver: "ok"。所以，运行这个：

RSpec.describe "have_received" do
  it "passes when the message has been received" do
    invitation = spy('invitation')
    invitation.deliver
    expect(invitation).to have_received(:deliver)
  end
end

RSpec.describe "have_received" do
  it "passes when the message has been received" do
    invitation = double('invitation')
    invitation.deliver
    expect(invitation).to have_received(:deliver)
  end
end

第一个例子将通过，但不是第二个。

现在我明白了这意味着......

“你可以使用任何测试双重（或部分双重）作为间谍，但必须设置双重监视你关心的消息。间谍​​自动监视所有消息，或者你可以允许消息窥探它。“