fix: Limit supported Python versions in --about output to existing …

…ones (#2180)

* fix: Limit supported Python versions in `--about` output to existing ones

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Increase test coverage

* Test static method

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

pyproject.toml

@@ -187,6 +187,7 @@ exclude_also = [
     '''if (t\.)?TYPE_CHECKING:''',
 ]
 fail_under = 82
+show_missing = true
 
 [tool.mypy]
 exclude = "tests"

singer_sdk/about.py

@@ -9,6 +9,9 @@
 from collections import OrderedDict
 from textwrap import dedent
 
+from packaging.specifiers import SpecifierSet
+from packaging.version import Version
+
 if t.TYPE_CHECKING:
     from singer_sdk.helpers.capabilities import CapabilitiesEnum
 
@@ -19,6 +22,38 @@
     "MarkdownFormatter",
 ]
 
+# Keep these in sync with the supported Python versions in pyproject.toml
+_PY_MIN_VERSION = 8
+_PY_MAX_VERSION = 12
+
+
+def _get_min_version(specifiers: SpecifierSet) -> int:
+    min_version: list[int] = []
+    for specifier in specifiers:
+        if specifier.operator == ">=":
+            min_version.append(Version(specifier.version).minor)
+        if specifier.operator == ">":
+            min_version.append(Version(specifier.version).minor + 1)
+    return min(min_version, default=_PY_MIN_VERSION)
+
+
+def _get_max_version(specifiers: SpecifierSet) -> int:
+    max_version: list[int] = []
+    for specifier in specifiers:
+        if specifier.operator == "<=":
+            max_version.append(Version(specifier.version).minor)
+        if specifier.operator == "<":
+            max_version.append(Version(specifier.version).minor - 1)
+    return max(max_version, default=_PY_MAX_VERSION)
+
+
+def get_supported_pythons(requires_python: str) -> t.Generator[str, None, None]:
+    specifiers = SpecifierSet(requires_python)
+    min_version = _get_min_version(specifiers)
+    max_version = _get_max_version(specifiers)
+
+    yield from specifiers.filter(f"3.{v}" for v in range(min_version, max_version + 1))
+
 
 @dataclasses.dataclass
 class AboutInfo:

singer_sdk/plugin_base.py

@@ -14,7 +14,6 @@
 
 import click
 from jsonschema import Draft7Validator
-from packaging.specifiers import SpecifierSet
 
 from singer_sdk import about, metrics
 from singer_sdk.cli import plugin_cli
@@ -36,30 +35,6 @@
 from singer_sdk.typing import extend_validator_with_defaults
 
 SDK_PACKAGE_NAME = "singer_sdk"
-CHECK_SUPPORTED_PYTHON_VERSIONS = (
-    # unsupported versions
-    "2.7",
-    "3.0",
-    "3.1",
-    "3.2",
-    "3.3",
-    "3.4",
-    "3.5",
-    "3.6",
-    "3.7",
-    # current supported versions
-    "3.8",
-    "3.9",
-    "3.10",
-    "3.11",
-    "3.12",
-    # future supported versions
-    "3.13",
-    "3.14",
-    "3.15",
-    "3.16",
-)
-
 
 JSONSchemaValidator = extend_validator_with_defaults(Draft7Validator)
 
@@ -300,12 +275,7 @@ def _get_supported_python_versions(package: str) -> list[str] | None:
         except metadata.PackageNotFoundError:
             return None
 
-        reported_python_versions = SpecifierSet(package_metadata["Requires-Python"])
-        return [
-            version
-            for version in CHECK_SUPPORTED_PYTHON_VERSIONS
-            if version in reported_python_versions
-        ]
+        return list(about.get_supported_pythons(package_metadata["Requires-Python"]))
 
     @classmethod
     def get_plugin_version(cls) -> str:

tests/core/test_about.py

@@ -3,11 +3,19 @@
 from __future__ import annotations
 
 import typing as t
+from importlib import metadata
 
 import pytest
 
-from singer_sdk.about import AboutFormatter, AboutInfo
+from singer_sdk.about import (
+    _PY_MAX_VERSION,
+    _PY_MIN_VERSION,
+    AboutFormatter,
+    AboutInfo,
+    get_supported_pythons,
+)
 from singer_sdk.helpers.capabilities import TapCapabilities
+from singer_sdk.plugin_base import SDK_PACKAGE_NAME
 
 if t.TYPE_CHECKING:
     from pathlib import Path
@@ -72,3 +80,26 @@ def test_about_format(
     output = formatter.format_about(about_info)
     snapshot_name = f"{about_format}.snap.{_format_to_extension[about_format]}"
     snapshot.assert_match(output, snapshot_name)
+
+
+def test_get_supported_pythons_sdk():
+    package_metadata = metadata.metadata(SDK_PACKAGE_NAME)
+    requires_python = package_metadata["Requires-Python"]
+
+    supported_pythons = list(get_supported_pythons(requires_python))
+    assert supported_pythons[0] == f"3.{_PY_MIN_VERSION}"
+    assert supported_pythons[-1] == f"3.{_PY_MAX_VERSION}"
+
+
+@pytest.mark.parametrize(
+    "specifiers,expected",
+    [
+        (">=3.7,<3.12", ["3.7", "3.8", "3.9", "3.10", "3.11"]),
+        (">=3.7", ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]),
+        (">3.7", ["3.8", "3.9", "3.10", "3.11", "3.12"]),
+        (">3.7,<=3.11", ["3.8", "3.9", "3.10", "3.11"]),
+    ],
+)
+def test_get_supported_pythons(specifiers: str, expected: list[str]):
+    supported_pythons = list(get_supported_pythons(specifiers))
+    assert supported_pythons == expected

tests/core/test_plugin_base.py

@@ -5,7 +5,7 @@
 
 import pytest
 
-from singer_sdk.plugin_base import MapperNotInitialized, PluginBase
+from singer_sdk.plugin_base import SDK_PACKAGE_NAME, MapperNotInitialized, PluginBase
 from singer_sdk.typing import IntegerType, PropertiesList, Property, StringType
 
 
@@ -53,3 +53,8 @@ def test_mapper_not_initialized():
     )
     with pytest.raises(MapperNotInitialized):
         _ = plugin.mapper
+
+
+def test_supported_python_versions():
+    """Test that supported python versions are correctly parsed."""
+    assert PluginBase._get_supported_python_versions(SDK_PACKAGE_NAME)