存根File.exists？在 RSpec

Question

我想测试以下 ruby 代码的 else 分支：

SCHEMA_SOURCE = if File.exist? SCHEMA_FILENAME
                  SCHEMA_FILENAME
                else
                  ContentfulApi::Http
                end

我找不到模拟文件不存在的方法 SCHEMA_FILENAME。下面是我试过的简化版测试，报错：

it 'fails to find file when it does not exist' do
  allow(File).to receive(:exists?).and_return(false)
  expect(File.exist?(ContentfulApi::SCHEMA_FILENAME)).to be_falsey
end

it 'fails to find file when it does not exist' do
  allow(File).to receive(:exists?).with(ContentfulApi::SCHEMA_FILENAME)\
                                  .and_return(false)
  expect(File.exist?(ContentfulApi::SCHEMA_FILENAME)).to be_falsey
end

这些都因错误而失败

expected: falsey value
got: true

it 'fails to find file when it does not exist' do
  File.stub(:exists?) { false }
  expect(File.exist?(ContentfulApi::SCHEMA_FILENAME)).to be_falsey
end

it 'fails to find file when it does not exist' do
  File.stub!(:exists?).with(ContentfulApi::SCHEMA_FILENAME)\
                      .and_return(false)
  expect(File.exist?(ContentfulApi::SCHEMA_FILENAME)).to be_falsey
end

这些都因错误而失败

undefined method `stub' for File:Class

我的前两次尝试遵循 Method Stubs 文档中的示例，尽管类和该文档中未探讨的对象之间可能存在区别。（虽然类 是 Ruby 中的对象，对吧？）

后两次尝试遵循 older documentation。

我应该如何存根 File.exist? SCHEMA_FILENAME 以便它 returns false 即使文件确实存在？

N.B。这些类似问题中的方法不起作用：

rspec to stub several File.exists? calls

Rspec -- need to stub File.open that gets called in another file

rspec undefined method stub for model

how to reset expectations on a mocked class method?

How do I stub out a specific file with rspec?

Can't stub things with Rspec

rspec 3 - stub a class method

Answer 1

你在嘲笑 File.exists? 并调用 File.exist?。

请注意，如果您设置了 verify_partial_doubles，并且您应该设置，RSpec 将不允许您模拟不存在的方法。

RSpec.configure do |config|
  config.mock_with :rspec do |mocks|
    mocks.verify_partial_doubles = true
  end
end

RSpec.describe File do
  it 'cannot mock a method whcih does not exist' do
    allow(File).to receive(:dslkfjalk).and_return(true)
  end
end

Failures:

  1) File cannot mock a method whcih does not exist
     Failure/Error: allow(File).to receive(:dslkfjalk).and_return(true)
       File does not implement: dslkfjalk

但是 File 确实有 exist? 和 exists? 两种方法。 File.exists? is deprecated 并从文档中删除，但我想它仍然...存在。

存根File.exists？在 RSpec

Stubbing File.exists? in RSpec

ruby

rspec

ruby-on-rails