Finding a word in txt file - Script TestComplete using Python

maybe its the classic python notation thats throwing the script editor off

if __name__ == '__main__':

so since its doing nothing but calling the functions into action, commented it out, and matched the indentation levels (using your code, the below should retain the format if you want to copy and paste, just replace the path to your file)

def test4():
  
  filename = 'C:\\Users\\justin.kim\\Desktop\\log.txt'

  def search(filename, text):
    with open(filename) as f:
     for line in f:
        if text in line:
           yield line

  #if __name__ == '__main__':
  for result in search(filename, 'Error'):
    Log.Message(result)