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如果没有任何实例,如何断言没有进行方法调用?

tdd rspec testing ruby-on-rails

Matilda Smeds Phrogz · 技术社区 · 6 年前

我有一门课,在某种情况下 :my_method ,但在另一种情况下不能调用方法 :我的方法 :我的方法 不应调用。

Using any_instance is generally discouraged ,所以我很乐意学习一种很好的方法来替换它。

这个代码片段是我想写的测试的简化示例。

class TestSubject
  def call
    call_me
  end

   def call_me; end
   def never_mind; end
end

require 'rspec'

spec = RSpec.describe 'TestSubject' do
  describe '#call' do
    it 'calls #call_me' do
      expect_any_instance_of(TestSubject).to receive(:call_me)
      TestSubject.new.call
    end

    it 'does not call #never_mind' do
      expect_any_instance_of(TestSubject).not_to receive(:never_mind)
      TestSubject.new.call
    end
  end
end

spec.run # => true

它工作,但使用 expect_any_instance_of

如何更换?

3 回复 | 直到 6 年前

kevcha 6 年前

我会做那样的事

describe TestSubject do
  describe '#call' do
    it 'does not call #something' do 
      subject = TestSubject.new
      allow(subject).to receive(:something)

      subject.call

      expect(subject).not_to have_received(:something)
    end
  end
end

希望这有帮助!

Jay-Ar Polidario 6 年前

我通常是这样进行单元测试的。我更新了代码以支持您(或其他读者)将来可能遇到的其他问题。

class TestSubject
  def call
    some_call_me_value = call_me
    call_you(some_call_me_value)
  end

  def call_me; end
  def call_you(x); end
  def never_mind; end

  class << self
    def some_class_method_a; end

    def some_class_method_b(x, y); end
  end
end

require 'rspec'

spec = RSpec.describe TestSubject do
  context 'instance methods' do
    let(:test_subject) { TestSubject.new }

    describe '#call' do
      let(:args) { nil }
      let(:mocked_call_me_return_value) { 'somecallmevalue' }
      subject { test_subject.call(*args) }

      before do
        allow(test_subject).to receive(:call_me) do
          mocked_call_me_return_value
        end
      end

      it 'calls #call_me' do
        expect(test_subject).to receive(:call_me).once
        subject
      end

      it 'calls #call_you with call_me value as the argument' do
        expect(test_subject).to receive(:call_you).once.with(mocked_call_me_return_value)
        subject
      end

      it 'does not call #never_mind' do
        expect(test_subject).to_not receive(:never_mind)
        subject
      end

      it 'calls in order' do
        expect(test_subject).to receive(:call_me).once.ordered
        expect(test_subject).to receive(:call_you).once.ordered
        subject
      end
    end

    describe '#call_me' do
      let(:args) { nil }
      subject { test_subject.call_me(*args) }

      # it ...
    end

    describe '#call_you' do
      let(:args) { nil }
      subject { test_subject.call_you(*args) }

      shared_examples_for 'shared #call_you behaviours' do
        it 'calls your phone number'
        it 'creates a Conversation record'
      end

      # just an example of argument-dependent behaviour spec
      context 'when argument is true' do 
        let(:args) { [true] }

        it 'does something magical'
        it_behaves_like 'shared #call_you behaviours'
      end

      # just an example of argument-dependent behaviour spec
      context 'when argument is false' do
        let(:args) { [false] }

        it 'does something explosive'
        it_behaves_like 'shared #call_you behaviours'
      end
    end
  end

  context 'class methods' do
    let(:args) { nil }

    describe '#some_class_method_a' do
      let(:args) { nil }
      subject { TestSubject.some_class_method_a(*args) }

      # it ...
    end

    describe '#some_class_method_b' do
      let(:args) { [1, 2] }
      subject { TestSubject.some_class_method_b(*args) }

      # it ...
    end
  end
end

spec.run # => true

Fabio 6 年前

这将使您的测试紧跟实现细节,并将迫使您在每次重构(在不改变行为的情况下改变实现细节)您的被测类时都改变测试。

而是针对返回值或更改的应用程序状态进行测试。
很难想出这个例子,你没有提供足够的上下文关于测试中的类。

class CreateEntity
  def initialize(name)
    @name = name
  end 

  def call
    if company_name?(@name)
      create_company
    else
      create_person
    end
  end

  def create_person
    Person.create!(:name => @name)
  end

  def create_company
    Company.create!(:name => @name)
  end
end

# tests

RSpec.describe CreateEntity do
  let(:create) { CreateEntity.new(name).call }

  describe '#call' do
    context 'when person name is given' do
      let(:name) { 'Firstname Lastname' }
      it 'creates a person' do
        expect { create }.to change { Person.count }.by(1) 
      end

      it 'do not create a company' do
        expect { create }.not_to change { Company.count }
      end
    end

    context 'when company name is given' do
      let(:name) { 'Name & Sons Ltd' }
      it 'creates a company' do
        expect { create }.to change { Company.count }.by(1) 
      end

      it 'do not create a person' do
        expect { create }.not_to change { Person.count }
      end
    end
  end
end

通过以上测试,我将能够改变 CreateEntity.call