ruby - 如何使用 rspec 测试 DSL API 方法

Question

我想测试一个方法是否接收到一个 block ...但是我的 rspec stub 返回 (no args)。

这是一个人为的例子......

class Foo
  def self.bar &block
  end
end

describe Foo do
  before do
    Foo.stub(:bar)
    Foo.bar { 'foo'}
  end
  it 'should' do
    expect(Foo).to have_received(:bar).with(kind_of(Proc))
  end
end

结果...

  1) Foo should
     Failure/Error: expect(Foo).to have_received(:bar).with(kind_of(Proc))
       <Foo (class)> received :bar with unexpected arguments
         expected: (#<RSpec::Mocks::ArgumentMatchers::KindOf:0x1022a7b20 @klass=Proc>)
              got: (no args)

编辑

这里是一个不太无意义的例子，其中实现了 Peter 的解决方案......

foo.rb

class Foo
  def self.setup &block
    @setup ||= block
  end
  def setup
    instance_eval &self.class.setup
  end
end

bar.rb

# DSL designed class
class Bar < Foo
  setup do
    # setup Bar instances here
  end
end

bar_spec.rb

# Need to make sure DSL classes are correctly implemented
describe Bar do
  after do
    load 'bar'
  end

  it 'should define .setup' do
    expect(Bar).to receive(:setup){ |&block| expect(block).to be_a(Proc) }
  end
end

Answer 1

我认为没有任何方法可以在事后验证 block 是否已通过，但如果您使用正常的执行前预期，则可以按如下方式检查它:

class Foo
  def self.bar &block
    puts 'DO NOT RUN'
  end
end

describe 'Foo#bar' do
  it 'should confirm a block is passed' do
    expect(Foo).to receive(:bar) {|&block| expect(block).to be_a(Proc)}
    Foo.bar {}
  end
  it 'should confirm a block is not passed' do
    expect(Foo).to receive(:bar) {|&block| expect(block).to be_nil}
    Foo.bar
  end
end

如果您不介意实际屈服于该 block ，则可以使用 .and_yield，如果 block 不存在，这将产生预期错误。

class Foo
  def self.bar &block
  end
end

describe Foo do
  before do
    Foo.stub(:bar), y
  end
  it 'should' do
    expect(Foo).to receive(:bar).and_yield
    Foo.bar {}
  end
end