class_docstr: Test case of invalid pipe interface 
docstr: target: test concat() API for invalid scenario
  method: 1. Concat pipe not existed
          2. Concat pipelines which have conflicting apis
          3. concat empty
  expected: raise exception
docstr_tok: ["target",":","test","concat","(",")","API","for","invalid","scenario","method",":","1",".","Concat","pipe","not","existed","2",".","Concat","pipelines","which","have","conflicting","apis","3.","concat","empty","expected",":","raise","exception"]
code: def test_data_collection_concat_invalid(self):
      """
      target: test concat() API for invalid scenario
      method: 1. Concat pipe not existed
              2. Concat pipelines which have conflicting apis
              3. concat empty
      expected: raise exception
      """
      # 1. Concat pipe not existed
      try:
          pipe0 = towhee.pipe.input("a", "b", "c")
          pipe2 = pipe0.map(("b", "c"), "e", lambda x, y: x - y)
          pipe2.concat(pipe).output("d", "e")
      except Exception as e:
          assert "the parameter of concat must be Pipeline" in str(e)
  
      # 3. Concat pipelines which have conflicting apis
      try:
          pipe0 = towhee.pipe.input("a")
          pipe1 = pipe0.map("a", "b", lambda x: x + 1).output("b")
          pipe2 = pipe0.map("a", "c", lambda x: x + 2).output("c")
          towhee.pipe.concat(pipe1, pipe2).output("b", "c")
      except Exception as e:
          assert "has no attribute" in str(e)
  
      # 4. concat empty
      try:
          pipe4 = towhee.pipe.input("a").map("a", "b", lambda x: x + 1)
          pipe4.concat().output("b")
      except Exception as e:
          assert "The parameter of concat cannot be None" in str(e)
  
      return True
  
imports: import sys
  import towhee
  import time
  import threading
  import numpy
  import random
  import operator
  from common import common_func
  from towhee import pipe, ops
label_desc: Use image node_id 8 for calling the TestPipeAPIsInvalid obj's underlying member method code with example usage: obj.test_data_collection_concat_invalid() and returns: True