RSpec 中的测试模块

激进的方式=>

let(:dummy_class) { Class.new { include ModuleToBeTested } }

或者，您可以使用您的模块扩展测试类：

let(:dummy_class) { Class.new { extend ModuleToBeTested } }

使用 'let' 比使用实例变量在 before(:each) 中定义虚拟类更好

When to use RSpec let()?

---

迈克说了什么。这是一个简单的例子：

模块代码...

module Say
  def hello
    "hello"
  end
end

规格片段...

class DummyClass
end

before(:each) do
  @dummy_class = DummyClass.new
  @dummy_class.extend(Say)
end

it "get hello string" do
  expect(@dummy_class.hello).to eq "hello"
end

---

对于可以单独测试或通过模拟类进行测试的模块，我喜欢以下内容：

模块：

module MyModule
  def hallo
    "hallo"
  end
end

规格：

describe MyModule do
  include MyModule

  it { hallo.should == "hallo" }
end

劫持嵌套的示例组似乎是错误的，但我喜欢简洁。有什么想法吗？

---

我在 rspec 主页找到了更好的解决方案。显然它支持共享示例组。来自https://www.relishapp.com/rspec/rspec-core/v/2-13/docs/example-groups/shared-examples！

共享示例组 您可以创建共享示例组并将这些组包含到其他组中。假设您有一些行为适用于产品的所有版本，无论大小。首先，排除“共享”行为：

shared_examples_for "all editions" do   
  it "should behave like all editions" do   
  end 
end

然后，当您需要为大版本和小版本定义行为时，请使用 it_should_behave_like() 方法引用共享行为。

describe "SmallEdition" do  
  it_should_behave_like "all editions"
  it "should also behave like a small edition" do   
  end 
end

---

在我的脑海中，你能在你的测试脚本中创建一个虚拟类并将模块包含在其中吗？然后测试虚拟类是否具有您期望的行为。

编辑：如果，正如评论中所指出的，模块期望某些行为出现在它所混合的类中，那么我会尝试实现这些行为的假人。足以让模块愉快地履行其职责。

也就是说，当一个模块对它的宿主（我们说“宿主”？）类有很多期望时，我会对我的设计有点紧张 - 如果我还没有从基类继承或无法注入将新功能添加到继承树中，然后我想我会尽量减少模块可能具有的任何此类期望。我担心我的设计会开始发展一些令人不快的僵化领域。

---

接受的答案是我认为的正确答案，但是我想添加一个示例如何使用 rpsecs shared_examples_for 和 it_behaves_like 方法。我在代码段中提到了一些技巧，但有关详细信息，请参阅此 relishapp-rspec-guide。

有了这个，您可以在任何包含它的类中测试您的模块。因此，您实际上是在测试您在应用程序中使用的内容。

让我们看一个例子：

# Lets assume a Movable module
module Movable
  def self.movable_class?
    true
  end

  def has_feets?
    true
  end
end

# Include Movable into Person and Animal
class Person < ActiveRecord::Base
  include Movable
end

class Animal < ActiveRecord::Base
  include Movable
end

现在让我们为我们的模块创建规范：movable_spec.rb

shared_examples_for Movable do
  context 'with an instance' do
    before(:each) do
      # described_class points on the class, if you need an instance of it: 
      @obj = described_class.new

      # or you can use a parameter see below Animal test
      @obj = obj if obj.present?
    end

    it 'should have feets' do
      @obj.has_feets?.should be_true
    end
  end

  context 'class methods' do
    it 'should be a movable class' do
      described_class.movable_class?.should be_true
    end
  end
end

# Now list every model in your app to test them properly

describe Person do
  it_behaves_like Movable
end

describe Animal do
  it_behaves_like Movable do
    let(:obj) { Animal.new({ :name => 'capybara' }) }
  end
end

---

要测试您的模块，请使用：

describe MyCoolModule do
  subject(:my_instance) { Class.new.extend(described_class) }

  # examples
end

要干燥您在多个规范中使用的某些内容，您可以使用共享上下文：

RSpec.shared_context 'some shared context' do
  let(:reused_thing)       { create :the_thing }
  let(:reused_other_thing) { create :the_thing }

  shared_examples_for 'the stuff' do
    it { ... }
    it { ... }
  end
end

require 'some_shared_context'

describe MyCoolClass do
  include_context 'some shared context'

  it_behaves_like 'the stuff'

  it_behaves_like 'the stuff' do
    let(:reused_thing) { create :overrides_the_thing_in_shared_context }
  end
end

资源：

共享示例

共享上下文

更好的规格

---

我最近的工作，尽可能少地使用硬接线

require 'spec_helper'

describe Module::UnderTest do
  subject {Object.new.extend(described_class)}

  context '.module_method' do
    it {is_expected.to respond_to(:module_method)}
    # etc etc
  end
end

我希望

subject {Class.new{include described_class}.new}

工作，但它没有（如在 Ruby MRI 2.2.3 和 RSpec::Core 3.3.0）

Failure/Error: subject {Class.new{include described_class}.new}
  NameError:
    undefined local variable or method `described_class' for #<Class:0x000000063a6708>

显然 describe_class 在该范围内不可见。

---

关于什么：

describe MyModule do
  subject { Object.new.extend(MyModule) }
  it "does stuff" do
    expect(subject.does_stuff?).to be_true
  end
end

---

我建议对于更大和更常用的模块，应该选择@Andrius here 建议的“共享示例组”。对于您不想遇到多个文件等麻烦的简单内容，以下是如何确保最大程度地控制虚拟内容的可见性（使用 rspec 2.14.6 测试，只需将代码复制并粘贴到spec 文件并运行它）：

module YourCoolModule
  def your_cool_module_method
  end
end

describe YourCoolModule do
  context "cntxt1" do
    let(:dummy_class) do
      Class.new do
        include YourCoolModule

        #Say, how your module works might depend on the return value of to_s for
        #the extending instances and you want to test this. You could of course
        #just mock/stub, but since you so conveniently have the class def here
        #you might be tempted to use it?
        def to_s
          "dummy"
        end

        #In case your module would happen to depend on the class having a name
        #you can simulate that behaviour easily.
        def self.name
          "DummyClass"
        end
      end
    end

    context "instances" do
      subject { dummy_class.new }

      it { subject.should be_an_instance_of(dummy_class) }
      it { should respond_to(:your_cool_module_method)}
      it { should be_a(YourCoolModule) }
      its (:to_s) { should eq("dummy") }
    end

    context "classes" do
      subject { dummy_class }
      it { should be_an_instance_of(Class) }
      it { defined?(DummyClass).should be_nil }
      its (:name) { should eq("DummyClass") }
    end
  end

  context "cntxt2" do
    it "should not be possible to access let methods from anohter context" do
      defined?(dummy_class).should be_nil
    end
  end

  it "should not be possible to access let methods from a child context" do
    defined?(dummy_class).should be_nil
  end
end

#You could also try to benefit from implicit subject using the descbie
#method in conjunction with local variables. You may want to scope your local
#variables. You can't use context here, because that can only be done inside
#a describe block, however you can use Porc.new and call it immediately or a
#describe blocks inside a describe block.

#Proc.new do
describe "YourCoolModule" do #But you mustn't refer to the module by the
  #constant itself, because if you do, it seems you can't reset what your
  #describing in inner scopes, so don't forget the quotes.
  dummy_class = Class.new { include YourCoolModule }
  #Now we can benefit from the implicit subject (being an instance of the
  #class whenever we are describing a class) and just..
  describe dummy_class do
    it { should respond_to(:your_cool_module_method) }
    it { should_not be_an_instance_of(Class) }
    it { should be_an_instance_of(dummy_class) }
    it { should be_a(YourCoolModule) }
  end
  describe Object do
    it { should_not respond_to(:your_cool_module_method) }
    it { should_not be_an_instance_of(Class) }
    it { should_not be_an_instance_of(dummy_class) }
    it { should be_an_instance_of(Object) }
    it { should_not be_a(YourCoolModule) }
  end
#end.call
end

#In this simple case there's necessarily no need for a variable at all..
describe Class.new { include YourCoolModule } do
  it { should respond_to(:your_cool_module_method) }
  it { should_not be_a(Class) }
  it { should be_a(YourCoolModule) }
end

describe "dummy_class not defined" do
  it { defined?(dummy_class).should be_nil }
end

---

你也可以使用辅助类型

# api_helper.rb
module Api
  def my_meth
    10
  end
end

# spec/api_spec.rb
require "api_helper"

RSpec.describe Api, :type => :helper do
  describe "#my_meth" do
    it { expect( helper.my_meth ).to eq 10 }
  end
end

这是文档：https://www.relishapp.com/rspec/rspec-rails/v/3-3/docs/helper-specs/helper-spec

---

您只需将模块包含到您的规范文件 mudule Test module MyModule def test 'test' end end end 中的规范文件 RSpec.describe Test::MyModule do include Test::MyModule #you can call directly the method *test* it 'returns test' do expect(test).to eql('test') end end

---

测试模块方法的一种可能解决方案，该方法独立于包含它们的类

module moduleToTest
  def method_to_test
    'value'
  end
end

并为其指定规格

describe moduleToTest do
  let(:dummy_class) { Class.new { include moduleToTest } }
  let(:subject) { dummy_class.new }

  describe '#method_to_test' do
    it 'returns value' do
      expect(subject.method_to_test).to eq('value')
    end
  end
end

如果您想对它们进行 DRY 测试，那么 shared_examples 是一个不错的方法

---

这是一种反复出现的模式，因为您将需要测试多个模块。出于这个原因，为此创建一个助手是非常可取的。

我发现 this post 解释了如何做，但我在这里应付，因为该网站可能会在某个时候被删除。

这是为了避免 object instances do not implement the instance method: :whatever 错误，您在尝试使用 dummy 类的 allow 方法时会遇到错误。

代码：

在 spec/support/helpers/dummy_class_helpers.rb

module DummyClassHelpers

  def dummy_class(name, &block)
    let(name.to_s.underscore) do
      klass = Class.new(&block)

      self.class.const_set name.to_s.classify, klass
    end
  end

end

在 spec/spec_helper.rb

# skip this if you want to manually require
Dir[File.expand_path("../support/**/*.rb", __FILE__)].each {|f| require f}

RSpec.configure do |config|
  config.extend DummyClassHelpers
end

在您的规格中：

require 'spec_helper'

RSpec.shared_examples "JsonSerializerConcern" do

  dummy_class(:dummy)

  dummy_class(:dummy_serializer) do
     def self.represent(object)
     end
   end

  describe "#serialize_collection" do
    it "wraps a record in a serializer" do
      expect(dummy_serializer).to receive(:represent).with(an_instance_of(dummy)).exactly(3).times

      subject.serialize_collection [dummy.new, dummy.new, dummy.new]
    end
  end
end

---