code: def test_custom_route_pattern_404(custom_pages_client):
      response = custom_pages_client.get("/route_OhNo")
      assert response.status == 404
      assert "<h1>Error 404</h1>" in response.text
      assert ">Oh no</" in response.text
  
file_path: datasette/tests/test_custom_pages.py
imports: import pathlib
  import pytest
  from .fixtures import make_app_client
label_desc: Use image node_id 13 for calling a global function with example usage: test_custom_route_pattern_404(custom_pages_client) without return types