Use tomllib on Python 3.11 (#1359)

Co-authored-by: hauntsaninja <>

coverage/tomlconfig.py

@@ -6,16 +6,21 @@
 import configparser
 import os
 import re
+import sys
 
 from coverage.exceptions import ConfigError
 from coverage.misc import import_third_party, substitute_variables
 
-# TOML support is an install-time extra option. (Import typing is here because
-# import_third_party will unload any module that wasn't already imported.
-# tomli imports typing, and if we unload it, later it's imported again, and on
-# Python 3.6, this causes infinite recursion.)
-import typing   # pylint: disable=unused-import, wrong-import-order
-tomli = import_third_party("tomli")
+if sys.version_info >= (3, 11):
+    import tomllib
+else:
+    # TOML support on Python 3.10 and below is an install-time extra option.
+    # (Import typing is here because import_third_party will unload any module
+    # that wasn't already imported. tomli imports typing, and if we unload it,
+    # later it's imported again, and on Python 3.6, this causes infinite
+    # recursion.)
+    import typing   # pylint: disable=unused-import, wrong-import-order
+    tomllib = import_third_party("tomli")
 
 
 class TomlDecodeError(Exception):
@@ -45,11 +50,11 @@ def read(self, filenames):
                 toml_text = fp.read()
         except OSError:
             return []
-        if tomli is not None:
+        if tomllib is not None:
             toml_text = substitute_variables(toml_text, os.environ)
             try:
-                self.data = tomli.loads(toml_text)
-            except tomli.TOMLDecodeError as err:
+                self.data = tomllib.loads(toml_text)
+            except tomllib.TOMLDecodeError as err:
                 raise TomlDecodeError(str(err)) from err
             return [filename]
         else:

setup.py

@@ -108,7 +108,7 @@ def better_set_verbosity(v):
 
     extras_require={
         # Enable pyproject.toml support.
-        'toml': ['tomli'],
+        'toml': ['tomli; python_version < "3.11"'],
     },
 
     # We need to get HTML assets from our htmlfiles directory.

tests/test_config.py

@@ -4,6 +4,7 @@
 """Test the config file handling for coverage.py"""
 
 import math
+import sys
 from collections import OrderedDict
 
 from unittest import mock
@@ -706,27 +707,29 @@ def test_note_is_obsolete(self):
 
     def test_no_toml_installed_no_toml(self):
         # Can't read a toml file that doesn't exist.
-        with without_module(coverage.tomlconfig, 'tomli'):
+        with without_module(coverage.tomlconfig, 'tomllib'):
             msg = "Couldn't read 'cov.toml' as a config file"
             with pytest.raises(ConfigError, match=msg):
                 coverage.Coverage(config_file="cov.toml")
 
+    @pytest.mark.skipif(sys.version_info >= (3, 11), reason="Python 3.11 has toml in stdlib")
     def test_no_toml_installed_explicit_toml(self):
         # Can't specify a toml config file if toml isn't installed.
         self.make_file("cov.toml", "# A toml file!")
-        with without_module(coverage.tomlconfig, 'tomli'):
+        with without_module(coverage.tomlconfig, 'tomllib'):
             msg = "Can't read 'cov.toml' without TOML support"
             with pytest.raises(ConfigError, match=msg):
                 coverage.Coverage(config_file="cov.toml")
 
+    @pytest.mark.skipif(sys.version_info >= (3, 11), reason="Python 3.11 has toml in stdlib")
     def test_no_toml_installed_pyproject_toml(self):
         # Can't have coverage config in pyproject.toml without toml installed.
         self.make_file("pyproject.toml", """\
             # A toml file!
             [tool.coverage.run]
             xyzzy = 17
             """)
-        with without_module(coverage.tomlconfig, 'tomli'):
+        with without_module(coverage.tomlconfig, 'tomllib'):
             msg = "Can't read 'pyproject.toml' without TOML support"
             with pytest.raises(ConfigError, match=msg):
                 coverage.Coverage()
@@ -738,7 +741,7 @@ def test_no_toml_installed_pyproject_no_coverage(self):
             [tool.something]
             xyzzy = 17
             """)
-        with without_module(coverage.tomlconfig, 'tomli'):
+        with without_module(coverage.tomlconfig, 'tomllib'):
             cov = coverage.Coverage()
             # We get default settings:
             assert not cov.config.timid

tests/test_testing.py

@@ -357,10 +357,10 @@ def _same_python_executable(e1, e2):
 
 
 def test_without_module():
-    toml1 = tomlconfig.tomli
-    with without_module(tomlconfig, 'tomli'):
-        toml2 = tomlconfig.tomli
-    toml3 = tomlconfig.tomli
+    toml1 = tomlconfig.tomllib
+    with without_module(tomlconfig, 'tomllib'):
+        toml2 = tomlconfig.tomllib
+    toml3 = tomlconfig.tomllib
 
     assert toml1 is toml3 is not None
     assert toml2 is None