remove F723 from docs

docs/source/user/error-codes.rst

@@ -93,8 +93,6 @@ generates its own :term:`error code`\ s for ``pyflakes``:
 +------+---------------------------------------------------------------------+
 | F722 | syntax error in forward annotation                                  |
 +------+---------------------------------------------------------------------+
-| F723 | syntax error in type comment                                        |
-+------+---------------------------------------------------------------------+
 +------+---------------------------------------------------------------------+
 | F811 | redefinition of unused ``name`` from line ``N``                     |
 +------+---------------------------------------------------------------------+

tests/unit/test_pyflakes_codes.py

@@ -2,6 +2,8 @@
 from __future__ import annotations
 
 import ast
+import os.path
+import re
 
 import pyflakes
 
@@ -18,6 +20,14 @@ def test_all_pyflakes_messages_have_flake8_codes_assigned():
     assert messages == set(pyflakes_shim.FLAKE8_PYFLAKES_CODES)
 
 
+def test_all_codes_documented():
+    here = os.path.dirname(__file__)
+    fname = os.path.join(here, '../../docs/source/user/error-codes.rst')
+    with open(fname) as f:
+        codes = set(re.findall(r'\bF\d{3}\b', f.read()))
+    assert set(pyflakes_shim.FLAKE8_PYFLAKES_CODES.values()) == codes
+
+
 def test_undefined_local_code():
     """In pyflakes 2.1.0 this code's string formatting was changed."""
     src = """\