Abort install if Requires-Python do not match the running version

Author: xavfernandez

CHANGES.txt

@@ -52,6 +52,8 @@
 
 * Normalize package names before using in ``pip show`` (:issue:`3976`)
 
+* Raises when Requires-Python do not match the running version.
+
 
 **8.1.2 (2016-05-10)**
 

pip/exceptions.py

@@ -237,3 +237,7 @@ def hash_then_or(hash_name):
                          self.gots[hash_name].hexdigest())
             prefix = '    or'
         return '\n'.join(lines)
+
+
+class UnsupportedPythonVersion(InstallationError):
+    """Unsupported python version (related to PEP 345 Requires-Python)."""

pip/req/req_set.py

@@ -20,6 +20,7 @@
     display_path, dist_in_usersite, ensure_dir, normalize_path)
 from pip.utils.hashes import MissingHashes
 from pip.utils.logging import indent_log
+from pip.utils.packaging import check_dist_requires_python
 from pip.vcs import vcs
 from pip.wheel import Wheel
 
@@ -655,6 +656,7 @@ def _prepare_file(self,
             # # parse dependencies # #
             # ###################### #
             dist = abstract_dist.dist(finder)
+            check_dist_requires_python(dist)
             more_reqs = []
 
             def add_req(subreq):

pip/utils/packaging.py

@@ -1,9 +1,15 @@
 from __future__ import absolute_import
+
+from email.parser import FeedParser
+
 import logging
 import sys
 
 from pip._vendor.packaging import specifiers
 from pip._vendor.packaging import version
+from pip._vendor import pkg_resources
+
+from pip import exceptions
 
 logger = logging.getLogger(__name__)
 
@@ -26,3 +32,32 @@ def check_requires_python(requires_python):
     # We only use major.minor.micro
     python_version = version.parse('.'.join(map(str, sys.version_info[:3])))
     return python_version in requires_python_specifier
+
+
+def get_metadata(dist):
+    if (isinstance(dist, pkg_resources.DistInfoDistribution) and
+            dist.has_metadata('METADATA')):
+        return dist.get_metadata('METADATA')
+    elif dist.has_metadata('PKG-INFO'):
+        return dist.get_metadata('PKG-INFO')
+
+
+def check_dist_requires_python(dist):
+    metadata = get_metadata(dist)
+    feed_parser = FeedParser()
+    feed_parser.feed(metadata)
+    pkg_info_dict = feed_parser.close()
+    requires_python = pkg_info_dict.get('Requires-Python')
+    try:
+        if not check_requires_python(requires_python):
+            raise exceptions.UnsupportedPythonVersion(
+                "%s requires Python '%s' but the running Python is %s" % (
+                    dist.project_name,
+                    requires_python,
+                    '.'.join(map(str, sys.version_info[:3])),)
+            )
+    except specifiers.InvalidSpecifier as e:
+        logger.debug(
+            "Package %s has an invalid Requires-Python entry %s - %s" % (
+                dist.project_name, requires_python, e))
+        return

tests/unit/test_utils.py

@@ -15,13 +15,15 @@
 import pytest
 
 from mock import Mock, patch
-from pip.exceptions import HashMismatch, HashMissing, InstallationError
+from pip.exceptions import (HashMismatch, HashMissing, InstallationError,
+                            UnsupportedPythonVersion)
 from pip.utils import (egg_link_path, get_installed_distributions,
                        untar_file, unzip_file, rmtree, normalize_path)
 from pip.utils.build import BuildDirectory
 from pip.utils.encoding import auto_decode
 from pip.utils.hashes import Hashes, MissingHashes
 from pip.utils.glibc import check_glibc_version
+from pip.utils.packaging import check_dist_requires_python
 from pip._vendor.six import BytesIO
 
 
@@ -524,3 +526,25 @@ def test_manylinux1_check_glibc_version(self):
                 else:
                     # Didn't find the warning we were expecting
                     assert False
+
+
+class TestCheckRequiresPython(object):
+
+    @pytest.mark.parametrize(
+        ("metadata", "should_raise"),
+        [
+            ("Name: test\n", False),
+            ("Name: test\nRequires-Python:", False),
+            ("Name: test\nRequires-Python: invalid_spec", False),
+            ("Name: test\nRequires-Python: <=1", True),
+        ],
+    )
+    def test_check_requires(self, metadata, should_raise):
+        fake_dist = Mock(
+            has_metadata=lambda _: True,
+            get_metadata=lambda _: metadata)
+        if should_raise:
+            with pytest.raises(UnsupportedPythonVersion):
+                check_dist_requires_python(fake_dist)
+        else:
+            check_dist_requires_python(fake_dist)