class_docstr: Test case of dag info 
class_docstr_tok: ["Test","case","of","dag","info"]
docstr: Unittest schema dag info
docstr_tok: ["Unittest","schema","dag","info"]
code: def test_schema_dag(self):
      """
      Unittest schema dag info
      """
      f = (
          towhee.dummy_input[(), ("video_url", "video_id")]()
          .set_parallel(5)
          .video_decode.ffmpeg[("video_url"), ("video_frame")]()
          .image_text_embedding.clip_image[
              ("video_frame"), ("embedding")
          ]()
          .image_decode.test[
              ("video_id", "video_frame", "embedding"), ()
          ]()
          .as_function()
      )
      for i in f.dag_info.values():
          if i["op_name"] == "start":
              expect_input = []
              expect_output = ["video_url", "video_id"]
              self.assertEqual(i["input_info"], expect_input)
              self.assertEqual(i["output_info"], expect_output)
          elif i["op_name"] == "video-decode/ffmpeg":
              expect_input = [("start", "video_url")]
              expect_output = ["video_frame"]
              self.assertEqual(i["input_info"], expect_input)
              self.assertEqual(i["output_info"], expect_output)
          elif i["op_name"] == "image-text-embedding/clip-image":
              expect_input = "video_frame"
              expect_output = ["embedding"]
              self.assertEqual(i["input_info"][0][1], expect_input)
              self.assertEqual(i["output_info"], expect_output)
          elif i["op_name"] == "image-decode/test":
              expect_input_1 = "video_id"
              expect_input_2 = "video_frame"
              expect_input_3 = "embedding"
              expect_output = []
              self.assertEqual(i["input_info"][0][1], expect_input_1)
              self.assertEqual(i["input_info"][1][1], expect_input_2)
              self.assertEqual(i["input_info"][2][1], expect_input_3)
              self.assertEqual(i["output_info"], expect_output)
          elif i["op_name"] == "end":
              self.assertEqual(i["input_info"], None)
              self.assertEqual(i["output_info"], None)
  
imports: import towhee
  import unittest
label_desc: Use image node_id 2 for calling the TestDagInfo obj's underlying member method code with example usage: obj.test_schema_dag() without return types