ruby - 如何测试使用 rspec 的 block 的函数

Question

我有一个函数，它接受一个 block ，打开一个文件，产生并返回:

def start &block
    .....do some stuff
    File.open("filename", "w") do |f|
        f.write("something")
        ....do some more stuff
        yield
    end
end

我正在尝试使用 rspec 为其编写测试。我如何 stub File.open 以便它将对象 f(由我提供)传递给 block 而不是尝试打开实际文件？像这样的东西:

it "should test something" do
    myobject = double("File", {'write' => true})
    File.should_receive(:open).with(&blk) do |myobject|
        f.should_receive(:write)
        blk.should_receive(:yield) (or somethig like that)
    end
end

Answer 1

我想你要找的是yield matchers ，即:

it "should test something" do
  # just an example
  expect { |b| my_object.start(&b) }.to yield_with_no_args
end