Simplify mechanism to get package version by using importlib

geomancy/checks/python.py

@@ -2,10 +2,8 @@
 Checks for python environment and packages
 """
 import typing as t
-import sys
-import subprocess
 import logging
-import re
+import importlib.metadata  # python >= 3.8
 
 from .version import CheckVersion
 from .utils import version_to_tuple
@@ -19,15 +17,6 @@
 class CheckPythonPackage(CheckVersion):
     """Check the availability and version of a python package"""
 
-    # use the pip freeze method
-    use_pip_freeze: bool = True
-
-    # The regex to use for parsing python package names
-    pip_pkg_str = r"^(?P<name>{pkg_name})\s*==\s*(?P<ver>[\d\w.]+)$"
-
-    # The results of pip freeze
-    pip_freeze: t.Union[str, None]
-
     # The message for checking python packages
     msg = Parameter(
         "CHECKPYTHONPACKAGE.MSG",
@@ -37,58 +26,20 @@ class CheckPythonPackage(CheckVersion):
     aliases = ("checkPythonPackage", "checkPythonPkg", "CheckPythonPkg")
 
     def get_current_version(self) -> t.Union[None, t.Tuple[int]]:
+        # Get the package name, operator and version to check against (the last
+        # 2 aren't used here)
         pkg_name, op, version = self.value
-        python = sys.executable  # current python interpreter
 
         # Nothing to do if the package name was not found
         if pkg_name is None:
             return None
 
-        # Method 1 -- try pip freeze
-        # First, try loading the freeze.
-        if self.use_pip_freeze and not hasattr(self, "pip_freeze"):
-            # "pip list" is used instead of "pip freeze" because "pip list"
-            # will not show paths--just package names--for packages installed
-            # from a local repository
-            args = (python, "-m", "pip", "list", "--format=freeze")
-            proc = subprocess.run(args=args, capture_output=True)
-
-            if proc.returncode != 0:
-                # This command didn't work. Set the class attribute for all
-                # instances
-                CheckPythonPackage.pip_freeze = None
-                logger.debug(f"Trying to use pip_freeze but couldn't run "
-                             f"'{args}'")
-            else:
-                CheckPythonPackage.pip_freeze = proc.stdout.decode("UTF-8")
-
-        # Parse the pip freeze
-        if getattr(self, "pip_freeze", None) is not None:
-            pattern = self.pip_pkg_str.format(pkg_name=pkg_name)
-            match = re.search(pattern, self.pip_freeze, re.MULTILINE)
-
-            # Convert the regex match to a version tuple
-            version = match.groupdict()["ver"] if match is not None else None
-            version = version_to_tuple(version) if version is not None else None
+        # Method 1 -- importlib.metadata
+        try:
+            # Returns a version string--e.g. '0.9.3'
+            version_string = importlib.metadata.version(pkg_name)
 
-            logger.debug(f"Found '{pkg_name}' package version '{version}' with "
-                         f"pip freeze.")
-            if version is not None:
-                return version
-
-        # Method 2 -- try importing and getting it from the __version__ string
-        code = f"import {pkg_name}; print({pkg_name}.__version__)"
-        proc = subprocess.run(args=(python, "-c", code), capture_output=True)
-
-        if proc.returncode == 0:
-            version_str = (
-                proc.stdout.decode("UTF-8").strip() if proc.stdout is not None else None
-            )
-            version = version_to_tuple(version_str) if version_str is not None else None
-
-            logger.debug(f"Found '{pkg_name}' package version '{version}' with "
-                         f"{pkg_name}.__version__")
-            return version
-
-        # I'm out of ideas. Version couldn't be parsed
-        return None
+            # Return the version tuple--e.g. (0, 9, 3)
+            return version_to_tuple(version_string) if version_string else None
+        except importlib.metadata.PackageNotFoundError:
+            return None

tests/checks/test_python.py

@@ -9,45 +9,7 @@
     pip = None
 
 
-@pytest.fixture
-def reset():
-    """Reset class caches"""
-    # Reset cached version, if populated by another test
-    if hasattr(CheckPythonPackage, "pip_freeze"):
-        del CheckPythonPackage.pip_freeze
-    return CheckPythonPackage
-
-
-@pytest.mark.skipif(pip is None, reason="pip must be installed")
-def test_check_python_package_get_current_version_pip(reset):
-    """Test the CheckPythonPackage get_current_version method with pip"""
-    # Check that pip_freeze can get populated
-    check = CheckPythonPackage(name="Python package", value="mypkg>=3.0")
-    check.use_pip_freeze = True
-
-    assert not hasattr(check, "pip_freeze")
-    check.get_current_version()
-    assert hasattr(check, "pip_freeze") and isinstance(check.pip_freeze, str)
-
-    # Substitute the pip freeze and see if the package version is correctly parsed
-    check.pip_freeze = ""
-    assert check.get_current_version() is None
-    check.pip_freeze = "\n".join(("more-itertools==9.1.0", "mypkg==3.0"))
-    assert check.get_current_version() == (3, 0)
-
-
-def test_check_python_package_get_current_version_no_pip(reset):
-    """Test the CheckPythonPackage get_current_version method without pip"""
-    check = CheckPythonPackage(name="Python package", value="pytest")
-    check.use_pip_freeze = False
-
-    version = check.get_current_version()
-    assert not hasattr(check, "pip_freeze")
-    assert version is not None  # A version should have been found for 'pytest'
-    assert isinstance(version, tuple)
-
-
-def test_check_python_package_exists(reset):
+def test_check_python_package_exists():
     """Tests CheckPythonPackage checking for an existing and a missing
     package"""
     # Should exist
@@ -59,7 +21,7 @@ def test_check_python_package_exists(reset):
     assert not check.check().passed
 
 
-def test_check_python_package_version(reset):
+def test_check_python_package_version():
     """Tests CheckPythonPackage checking with version number"""
     # Should be greater than version 1.0
     check = CheckPythonPackage(name="Check pytest", value="pytest>=1.0")