Move check_dist_requires_python() to resolve.py.

src/pip/_internal/resolve.py

@@ -15,6 +15,9 @@ import sys
 from collections import defaultdict
 from itertools import chain
 
+from pip._vendor.packaging import specifiers
+
+from pip._internal import exceptions
 from pip._internal.exceptions import (
     BestVersionAlreadyInstalled, DistributionNotFound, HashError, HashErrors,
     UnsupportedPythonVersion,
@@ -22,11 +25,12 @@ from pip._internal.exceptions import (
 from pip._internal.req.constructors import install_req_from_req_string
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import dist_in_usersite, ensure_dir
-from pip._internal.utils.packaging import check_dist_requires_python
+from pip._internal.utils.packaging import check_requires_python, get_metadata
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
-    from typing import Optional, DefaultDict, List, Set
+    from typing import DefaultDict, List, Optional, Set, Tuple
+    from pip._vendor import pkg_resources
     from pip._internal.download import PipSession
     from pip._internal.req.req_install import InstallRequirement
     from pip._internal.index import PackageFinder
@@ -39,6 +43,35 @@ if MYPY_CHECK_RUNNING:
 logger = logging.getLogger(__name__)
 
 
+def check_dist_requires_python(
+        dist,  # type: pkg_resources.Distribution
+        version_info,  # type: Optional[Tuple[int, ...]]
+):
+    # type: (...) -> None
+    """
+    :param version_info: A 3-tuple of ints representing the Python
+        major-minor-micro version to check (e.g. `sys.version_info[:3]`).
+    """
+    pkg_info_dict = get_metadata(dist)
+    requires_python = pkg_info_dict.get('Requires-Python')
+    try:
+        if not check_requires_python(
+            requires_python, version_info=version_info,
+        ):
+            raise exceptions.UnsupportedPythonVersion(
+                "%s requires Python '%s' but the running Python is %s" % (
+                    dist.project_name,
+                    requires_python,
+                    '.'.join(map(str, version_info)),)
+            )
+    except specifiers.InvalidSpecifier as e:
+        logger.warning(
+            "Package %s has an invalid Requires-Python entry %s - %s",
+            dist.project_name, requires_python, e,
+        )
+        return
+
+
 class Resolver(object):
     """Resolves which packages need to be installed/uninstalled to perform \
     the requested operation without breaking the requirements of any package.

src/pip/_internal/utils/packaging.py

@@ -6,7 +6,6 @@ from email.parser import FeedParser
 from pip._vendor import pkg_resources
 from pip._vendor.packaging import specifiers, version
 
-from pip._internal import exceptions
 from pip._internal.utils.misc import display_path
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
@@ -58,31 +57,6 @@ def get_metadata(dist):
     return feed_parser.close()
 
 
-def check_dist_requires_python(dist, version_info):
-    """
-    :param version_info: A 3-tuple of ints representing the Python
-        major-minor-micro version to check (e.g. `sys.version_info[:3]`).
-    """
-    pkg_info_dict = get_metadata(dist)
-    requires_python = pkg_info_dict.get('Requires-Python')
-    try:
-        if not check_requires_python(
-            requires_python, version_info=version_info,
-        ):
-            raise exceptions.UnsupportedPythonVersion(
-                "%s requires Python '%s' but the running Python is %s" % (
-                    dist.project_name,
-                    requires_python,
-                    '.'.join(map(str, version_info)),)
-            )
-    except specifiers.InvalidSpecifier as e:
-        logger.warning(
-            "Package %s has an invalid Requires-Python entry %s - %s",
-            dist.project_name, requires_python, e,
-        )
-        return
-
-
 def get_installer(dist):
     # type: (Distribution) -> str
     if dist.has_metadata('INSTALLER'):

tests/unit/test_resolve.py

@@ -0,0 +1,32 @@
+import sys
+
+import pytest
+from mock import Mock
+
+from pip._internal.exceptions import UnsupportedPythonVersion
+from pip._internal.resolve import check_dist_requires_python
+
+
+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)
+        version_info = sys.version_info[:3]
+        if should_raise:
+            with pytest.raises(UnsupportedPythonVersion):
+                check_dist_requires_python(
+                    fake_dist, version_info=version_info,
+                )
+        else:
+            check_dist_requires_python(fake_dist, version_info=version_info)

tests/unit/test_utils.py

@@ -20,7 +20,7 @@ import pytest
 from mock import Mock, patch
 
 from pip._internal.exceptions import (
-    HashMismatch, HashMissing, InstallationError, UnsupportedPythonVersion,
+    HashMismatch, HashMissing, InstallationError,
 )
 from pip._internal.utils.encoding import BOMS, auto_decode
 from pip._internal.utils.glibc import check_glibc_version
@@ -31,7 +31,6 @@ from pip._internal.utils.misc import (
     redact_password_from_url, remove_auth_from_url, rmtree,
     split_auth_from_netloc, split_auth_netloc_from_url, untar_file, unzip_file,
 )
-from pip._internal.utils.packaging import check_dist_requires_python
 from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
 from pip._internal.utils.ui import SpinnerInterface
 
@@ -699,31 +698,6 @@ class TestGlibc(object):
                     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)
-        version_info = sys.version_info[:3]
-        if should_raise:
-            with pytest.raises(UnsupportedPythonVersion):
-                check_dist_requires_python(
-                    fake_dist, version_info=version_info,
-                )
-        else:
-            check_dist_requires_python(fake_dist, version_info=version_info)
-
-
 class TestGetProg(object):
 
     @pytest.mark.parametrize(