code: def test_same_rev(tmp_dir, scm, dvc):
      tmp_dir.dvc_gen("file", "text", commit="add file")
  
      assert not dvc.diff("HEAD", "HEAD")
      assert not dvc.diff("HEAD", "master")
      assert not dvc.diff("master", "HEAD")
  
imports: import hashlib
  import os
  import pytest
  from funcy import first
  from dvc.exceptions import DvcException
  from dvc.utils.fs import remove
label_desc: Use image node_id 3 for calling a global function with example usage: test_same_rev(tmp_dir, scm, dvc) without return types