Rails：在模型规范中测试文件上传验证（Shrine gem）

Question

以下代码使用 RSpec 3.5 和用于文件上传的Shrine gem在 Rails 4.2 应用程序的模型规范内测试图像验证。

我的问题是：

• 您能想出一种改进以下测试的方法或更好的方法来测试这些验证吗？
• 如何提高文件大小验证测试的速度？如果可能的话，我想测试它，而无需实际上传>10mb的文件。

文件上传设置的其他方面在控制器和功能规范中进行了测试，这些与此问题无关。

RSpec.describe ShareImage, :type => :model do
  describe "#image", :focus do
    let(:image_file) do
      # Could not get fixture_file_upload to work, but that's irrelevant
      Rack::Test::UploadedFile.new(File.join(
        ActionController::TestCase.fixture_path, 'files', filename))
    end
    let(:share_image) { FactoryGirl.build(:share_image, image: image_file) }
    before(:each) { share_image.valid? }

    context "with a valid image file" do
      let(:filename) { 'image-valid.jpg' }
      it "attaches the image to this record" do
        expect(share_image.image.metadata["filename"]).to eq filename
      end
    end

    context "with JPG extension and 'text/plain' media type" do
      let(:filename) { 'image-with-text-media-type.jpg' }
      it "is invalid" do
        expect(share_image.errors[:image].to_s).to include("invalid file type")
      end
    end

    # TODO: Refactor the following test (it takes ~50 seconds to run)
    context "with a >10mb image file" do
      let(:filename) { 'image-11mb.jpg' }
      it "is invalid" do
        expect(share_image.errors[:image].to_s).to include("too large")
      end
    end
  end
end

Answer 1

我建议您单独测试元数据提取和验证。元数据提取需要使用真实 IO 进行测试，但对于验证测试，您可以分配具有所需元数据的缓存文件，该元数据不必实际存在。

RSpec.describe ImageUploader do
  def uploaded_file(metadata = {})
    Shrine.uploaded_file(
      "id"       => "123",
      "storage"  => "cache",
      "metadata" => {"mime_type" => "image/jpeg", "size" => 100}.merge(metadata)
    )
  end

  let(:share_image) do
    FactoryGirl.build(:share_image, image: uploaded_file(metadata).to_json)
  end

  let(:metadata) { Hash.new }

  describe "validations" do
    before(:each) { share_image.valid? }

    context "when image is correct" do
      it "passes" do
        expect(share_image.errors).to be_empty
      end
    end

    context "when extension is correct but MIME types isn't" do
      let(:metadata) { Hash["filename" => "image.jpg", mime_type => "text/plain"] }

      it "fails" do
        expect(share_image.errors[:image].to_s).to include("isn't of allowed type")
      end
    end

    context "when file is larger than 10MB" do
      let(:metadata) { Hash["size" => 11 * 1024 * 1024] }

      it "fails" do
        expect(share_image.errors[:image].to_s).to include("too large")
      end
    end
  end
end