Switch from toml to tomli/tomllib (#152)

* Switch from toml to tomli/tomllib

The toml package is unmaintained, so it was appropriate to move away
from it as a dependency. The tomli package is the most appropriate
alternative, because it was incorporated into the Python standard
library as of Python 3.11, under the name tomllib.

Due to the prevalence of tomli as a compulsory dependency of many other
Python code quality tools (such as black, mypy, pytest and pylint),
there's a big chance that users will already have it installed if
they're using Import Linter. Therefore, tomli is now a compulsory
dependency (if you're using versions of Python earlier than 3.11).

This change has several benefits:

- Reduces the overall number of dependencies in the average Python
  application
- Removes a dependency on an unmaintained project
- Reduces the complexity of configuration-related testing
- Greatly simplifies the tox configuration

Co-authored-by: Matthew Gamble <matthew.gamble@rea-group.com>

AUTHORS.rst

@@ -17,3 +17,4 @@ Contributors
 * Daniele Esposti - https://github.com/expobrain
 * Petter Friberg - https://github.com/flaeppe
 * James Owen - https://github.com/leamingrad
+* Matthew Gamble - https://github.com/mwgamble

CHANGELOG.rst

@@ -1,6 +1,11 @@
 Changelog
 =========
 
+latest
+------
+
+* Switch from optional dependency of ``toml`` to required dependency of ``tomli`` for Python versions < 3.11.
+
 1.6.0 (2022-12-7)
 -----------------
 

docs/toml.rst

@@ -40,7 +40,3 @@ Following, an example with a layered configuration:
         "medium",
         "low",
     ]
-
-Please note, that in order to use TOML files, you need to install the extra require ``toml``::
-
-    pip install import-linter[toml]

setup.py

@@ -51,8 +51,12 @@ def read(*names, **kwargs):
         "Topic :: Utilities",
     ],
     python_requires=">=3.7",
-    install_requires=["click>=6", "grimp>=2.0", "typing-extensions>=3.10.0.0"],
-    extras_require={"toml": ["toml"]},
+    install_requires=[
+        "click>=6",
+        "grimp>=2.0",
+        "tomli>=1.2.1; python_version < '3.11'",
+        "typing-extensions>=3.10.0.0",
+    ],
     entry_points={
         "console_scripts": ["lint-imports = importlinter.cli:lint_imports_command"]
     },

src/importlinter/adapters/user_options.py

@@ -1,13 +1,12 @@
 import configparser
 from typing import Any, Dict, Optional, List
 import abc
+import sys
 
-try:
-    import toml
-
-    _HAS_TOML = True
-except ImportError:
-    _HAS_TOML = False
+if sys.version_info >= (3, 11):
+    import tomllib
+else:
+    import tomli as tomllib
 
 from importlinter.application import file_finding
 from importlinter.application.app_config import settings
@@ -86,11 +85,8 @@ class TomlFileUserOptionReader(AbstractUserOptionReader):
     potential_config_filenames = ["pyproject.toml"]
 
     def _read_config_filename(self, config_filename: str) -> Optional[UserOptions]:
-        if not _HAS_TOML:
-            return None
-
         file_contents = settings.FILE_SYSTEM.read(config_filename)
-        data = toml.loads(file_contents)
+        data = tomllib.loads(file_contents)
 
         tool_data = data.get("tool", {})
         session_options = tool_data.get("importlinter", {})

tests/functional/test_lint_imports.py

@@ -30,50 +30,10 @@
         (testpackage_directory, ".externalbrokencontract.ini", cli.EXIT_STATUS_ERROR),
         (multipleroots_directory, ".multiplerootskeptcontract.ini", cli.EXIT_STATUS_SUCCESS),
         (multipleroots_directory, ".multiplerootsbrokencontract.ini", cli.EXIT_STATUS_ERROR),
-        # TOML versions.
-        pytest.param(
-            testpackage_directory,
-            ".setup.toml",
-            cli.EXIT_STATUS_ERROR,
-            marks=pytest.mark.toml_not_installed,
-        ),
-        pytest.param(
-            testpackage_directory,
-            ".setup.toml",
-            cli.EXIT_STATUS_SUCCESS,
-            marks=pytest.mark.toml_installed,
-        ),
-        pytest.param(
-            testpackage_directory,
-            ".customkeptcontract.toml",
-            cli.EXIT_STATUS_ERROR,
-            marks=pytest.mark.toml_not_installed,
-        ),
-        pytest.param(
-            testpackage_directory,
-            ".customkeptcontract.toml",
-            cli.EXIT_STATUS_SUCCESS,
-            marks=pytest.mark.toml_installed,
-        ),
-        pytest.param(
-            testpackage_directory,
-            ".customkeptcontract.toml",
-            cli.EXIT_STATUS_ERROR,
-            marks=pytest.mark.toml_not_installed,
-        ),
-        pytest.param(
-            testpackage_directory,
-            ".customkeptcontract.toml",
-            cli.EXIT_STATUS_SUCCESS,
-            marks=pytest.mark.toml_installed,
-        ),
+        (testpackage_directory, ".setup.toml", cli.EXIT_STATUS_SUCCESS),
+        (testpackage_directory, ".customkeptcontract.toml", cli.EXIT_STATUS_SUCCESS),
         (testpackage_directory, ".externalkeptcontract.ini", cli.EXIT_STATUS_SUCCESS),
-        pytest.param(
-            testpackage_directory,
-            ".externalkeptcontract.toml",
-            cli.EXIT_STATUS_SUCCESS,
-            marks=pytest.mark.toml_installed,
-        ),
+        (testpackage_directory, ".externalkeptcontract.toml", cli.EXIT_STATUS_SUCCESS),
         # Unmatched ignore imports alerting.
         # The return value depends on what this is set to.
         (

tests/unit/adapters/test_user_options.py

@@ -121,7 +121,6 @@ def test_respects_passed_filename(passed_filename, expected_foo_value):
         assert expected_options == options
 
 
-@pytest.mark.toml_installed
 @pytest.mark.parametrize(
     "contents, expected_options",
     (
@@ -190,24 +189,3 @@ def test_toml_file_reader(contents, expected_options):
 
     options = TomlFileUserOptionReader().read_options()
     assert expected_options == options
-
-
-@pytest.mark.toml_not_installed
-def test_toml_file_reader_returns_none_when_toml_not_installed():
-    valid_toml = """
-    [something]
-    foo = 1
-    bar = "hello"
-
-    [tool.importlinter]
-    foo = "hello"
-    bar = 999
-    """
-    settings.configure(
-        FILE_SYSTEM=FakeFileSystem(
-            content_map={"/path/to/folder/pyproject.toml": valid_toml},
-            working_directory="/path/to/folder",
-        )
-    )
-
-    assert TomlFileUserOptionReader().read_options() is None

tox.ini

@@ -3,7 +3,7 @@ envlist =
     clean,
     check,
     docs,
-    {py37,py38,py39,py310,py311}-{notoml,toml},
+    py37,py38,py39,py310,py311
     report
 
 [testenv]
@@ -25,24 +25,16 @@ deps =
     pytest-cov~=3.0.0
     PyYAML~=6.0
 commands =
-    {posargs:pytest -m "not toml_installed" --cov --cov-report=term-missing -vv tests}
-
-[testenv:{py37,py38,py39,py310,py311}-toml]
-deps =
-    {[testenv]deps}
-    toml~=0.10.2
-commands =
-    {posargs:pytest -m "not toml_not_installed" --cov --cov-report=term-missing -vv tests}
+    {posargs:pytest --cov --cov-report=term-missing -vv tests}
 
 
 [testenv:check]
 deps =
-    {[testenv:py311-toml]deps}
+    {[testenv]deps}
     black~=22.3.0
     flake8~=4.0.1
     mypy~=0.730
     types-PyYAML
-    types-toml
 commands =
     black --check src tests
     flake8 src tests setup.py
@@ -69,9 +61,10 @@ skip_install = true
 deps = coverage
 
 [gh-actions]
+# Run check on both Python 3.10 and 3.11, because of our version-dependent dependency on tomli.
 python =
     3.7: py37, report
     3.8: py38, report
     3.9: py39, report
-    3.10: py310, report
+    3.10: py310, report, check
     3.11: py311, report, check, docs