fix: target python version

Allow any valid python version to be set as the target version so that
users don't need to install a new package version each time a new Python
version is released.

Add tests for validating the target version configuration.

Clarify the meaning of the target version in the doc comment.

Fixes: #63

Author: stevenh

.gitignore

@@ -24,3 +24,4 @@ _build/
 /.ghtopdep_cache/
 /worktrees/
 /.ruff_cache/
+__pycache__/

pytest_examples/config.py

@@ -1,6 +1,7 @@
 from __future__ import annotations as _annotations
 
 import hashlib
+import re
 import tempfile
 from dataclasses import dataclass
 from pathlib import Path
@@ -21,7 +22,7 @@ class ExamplesConfig:
     line_length: int = DEFAULT_LINE_LENGTH
     quotes: Literal['single', 'double', 'either'] = 'either'
     magic_trailing_comma: bool = True
-    target_version: Literal['py37', 'py38', 'py39', 'py310', 'py311'] = 'py37'
+    target_version: str | None = 'py37'
     upgrade: bool = False
     isort: bool = False
     ruff_line_length: int | None = None
@@ -30,6 +31,11 @@ class ExamplesConfig:
     white_space_dot: bool = False
     """If True, replace spaces with `·` in example diffs."""
 
+    def __post_init__(self):
+        """Validate the configuration after initialization."""
+        if self.target_version and not re.match(r'py\d{2,}$', self.target_version):
+            raise ValueError(f'Invalid target version: {self.target_version!r}, must be like "py37"')
+
     def black_mode(self):
         return BlackMode(
             line_length=self.line_length,

pytest_examples/eval_example.py

@@ -37,7 +37,7 @@ def set_config(
         line_length: int = DEFAULT_LINE_LENGTH,
         quotes: Literal['single', 'double', 'either'] = 'either',
         magic_trailing_comma: bool = True,
-        target_version: Literal['py37', 'py38', 'py39', 'py310', 'py310'] = 'py37',
+        target_version: str | None = 'py37',
         upgrade: bool = False,
         isort: bool = False,
         ruff_line_length: int | None = None,
@@ -50,7 +50,7 @@ def set_config(
             line_length: The line length to use when wrapping print statements, defaults to 88.
             quotes: The quote to use, defaults to "either".
             magic_trailing_comma: If True, add a trailing comma to magic methods, defaults to True.
-            target_version: The target version to use when upgrading code, defaults to "py37".
+            target_version: The target version to use when checking and formatting code, defaults to "py37".
             upgrade: If True, upgrade the code to the target version, defaults to False.
             isort: If True, run ruff's isort extension on the code, defaults to False.
             ruff_line_length: In general, we disable line-length checks in ruff, to let black take care of them.

pytest_examples/lint.py

@@ -27,7 +27,7 @@ def ruff_format(
     *,
     ignore_errors: bool = False,
 ) -> str:
-    args = ('--fix',)
+    args: tuple[str, ...] = ('--fix',)
     if ignore_errors:
         args += ('--exit-zero',)
     try:

tests/test_config.py

@@ -0,0 +1,72 @@
+from dataclasses import dataclass
+from typing import Any
+
+import pytest
+
+from pytest_examples.config import ExamplesConfig
+
+
+@dataclass
+class TargetVersionTestCase:
+    id: str
+    target_version: Any
+
+
+@pytest.mark.parametrize(
+    'case',
+    [
+        # Valid target versions
+        TargetVersionTestCase('py37', 'py37'),
+        TargetVersionTestCase('py38', 'py38'),
+        TargetVersionTestCase('py39', 'py39'),
+        TargetVersionTestCase('py310', 'py310'),
+        TargetVersionTestCase('py311', 'py311'),
+        TargetVersionTestCase('py312', 'py312'),
+        TargetVersionTestCase('py313', 'py313'),
+        TargetVersionTestCase('py314', 'py314'),
+        TargetVersionTestCase('py3100', 'py3100'),
+    ],
+    ids=lambda case: case.id,
+)
+def test_examples_config_valid_target_version(case: TargetVersionTestCase):
+    """Test that ExamplesConfig validates target_version correctly during initialization."""
+    config = ExamplesConfig(target_version=case.target_version)
+    assert config.target_version == case.target_version
+
+
+@pytest.mark.parametrize(
+    'case',
+    [
+        TargetVersionTestCase('missing_py', '37'),
+        TargetVersionTestCase('python_word', 'python37'),
+        TargetVersionTestCase('single_digit', 'py3'),
+        TargetVersionTestCase('dots', 'py3.7'),
+        TargetVersionTestCase('spaces', 'py 37'),
+        TargetVersionTestCase('uppercase', 'PY37'),
+        TargetVersionTestCase('mixed_case', 'Py37'),
+        TargetVersionTestCase('letters_before_digits', 'py3a7'),
+        TargetVersionTestCase('hyphen', 'py-37'),
+        TargetVersionTestCase('underscore', 'py_37'),
+        TargetVersionTestCase('suffix', 'py37!'),
+        TargetVersionTestCase('text_suffix', 'py37abc'),
+    ],
+    ids=lambda case: case.id,
+)
+def test_examples_config_invalid_target_version(case: TargetVersionTestCase):
+    """Test that ExamplesConfig validates target_version correctly during initialization."""
+    with pytest.raises(ValueError, match=f'Invalid target version: {case.target_version!r}'):
+        ExamplesConfig(target_version=case.target_version)
+
+
+def test_examples_config_empty_string_target_version():
+    """Test that empty string target_version is accepted without validation."""
+    # Based on the validation logic, empty string should not raise an error
+    # because the check is 'if self.target_version' which is falsy for empty string
+    config = ExamplesConfig(target_version='')
+    assert config.target_version == ''
+
+
+def test_examples_config_target_version_error_message():
+    """Test that the error message includes the expected format."""
+    with pytest.raises(ValueError, match='must be like "py37"'):
+        ExamplesConfig(target_version='invalid')