title: Using pytest to write test code for Tkinter
body: <p>I am using pytest to test a to do list program that uses tkinter but when I run my test code the pytest code in the terminal doesn't run. I am not sure if my test code is bad or if I am not calling something correctly but I would love any and all help.</p>
  <p>code:</p>
  <pre><code>from tkinter import Entry, Listbox
  import pytest
  from to_do_list import add_item, delete_item
  
  def test_add_item():
      assert add_item('test') == 'test'
  
  def test_delete_item():
      test_delete = delete_item()
      assert not test_delete == 'test'
  </code></pre>
  <p>Code I am trying to test:</p>
  <pre><code>def add_item(entry: Entry, listbox:Listbox):
      new_item = entry.get()
      listbox.insert(END, new_item)
      with open('items.txt', 'a') as item_file:
          item_file.write(f'\n{new_item}')
  
  def delete_item(listbox: Listbox):
      listbox.delete(ACTIVE)
      with open('items.txt', 'r+') as item_file:
          lines = item_file.readlines()
          for line in lines:
              if listbox.get(ACTIVE) == line[:-2]:
                  lines.remove(line)
              item_file.write(line)
          item_file.close()
  </code></pre>
  <p>In my main code, I have it open a window using this code at the bottom of the code.</p>
  <pre><code>window.update()
  window.mainloop()
  </code></pre>