Question

我正在为使用外部服务的Rails项目编写规范（在本例中为Aws :: S3）。我会在upload_file的任何实例上存根调用Aws::S3::Object，并且能够在事后检查此类的实例是否已接到对upload_file的调用。

到目前为止我做了什么：

allow_any_instance_of(Aws::S3::Object).to receive(:upload_file).and_return('Stubbed!')

和

expect_any_instance_of(Aws::S3::Object).to receive(:upload_file)

但不知怎的，期望不起作用（我的代码调用upload_file但RSpec没有看到它。）

Answer 1

继续前进，我建议避免使用x_any_instance_of方法outlined in the RSpec Mocks documentation。

相反，在.new类上隐藏对Aws::S3::Object的调用，并让instance_double代表在您的应用中初始化的实际对象，以便您可以进行断言在它上面。

这里有一些比较两种语法的示例代码和规范：

module Aws
  module S3
    class Object
      def upload_file
        # upload the file
      end
    end
  end
end

class FileUploader
  def self.upload
    Aws::S3::Object.new.upload_file
  end
end

RSpec.describe FileUploader do
  describe '.upload' do
    context 'using any_instance_of' do
      before do
        allow_any_instance_of(Aws::S3::Object).to receive(:upload_file)
      end

      it 'calls to upload the file on the S3 Object' do
        expect_any_instance_of(Aws::S3::Object).to receive(:upload_file)
        described_class.upload
      end
    end

    context 'using an instance double' do
      let(:s3_object) { instance_double('Aws::S3::Object') }

      context 'stubbing a method to return the double on allow' do
        before do
          allow(Aws::S3::Object).to receive(:new).and_return(s3_object)
        end

        it 'uploads the file on the S3 Object' do
          expect(s3_object).to receive(:upload_file)
          described_class.upload
        end
      end

      context 'stubbing a method to return the double on expect' do
        it 'uploads the file on the S3 Object' do
          expect(Aws::S3::Object).to receive(:new).and_return(s3_object)
          expect(s3_object).to receive(:upload_file)
          described_class.upload
        end
      end
    end
  end
end

存储服务的实例方法并检查它是否收到了对它的调用

1 个答案: