Fix bypassed pip upgrade warning on Windows

Merge pull request #6864 from atugushev/fix-issue-6841

news/6841.bugfix

@@ -0,0 +1 @@
+Fix bypassed pip upgrade warning on Windows.

src/pip/_internal/utils/misc.py

@@ -1299,11 +1299,11 @@ def protect_pip_from_modification_on_windows(modifying_pip):
     On Windows, any operation modifying pip should be run as:
         python -m pip ...
     """
-    pip_names = [
-        "pip.exe",
-        "pip{}.exe".format(sys.version_info[0]),
-        "pip{}.{}.exe".format(*sys.version_info[:2])
-    ]
+    pip_names = set()
+    for ext in ('', '.exe'):
+        pip_names.add('pip{ext}'.format(ext=ext))
+        pip_names.add('pip{}{ext}'.format(sys.version_info[0], ext=ext))
+        pip_names.add('pip{}.{}{ext}'.format(*sys.version_info[:2], ext=ext))
 
     # See https://github.com/pypa/pip/issues/1299 for more discussion
     should_show_use_python_msg = (

tests/functional/test_install.py

@@ -8,6 +8,7 @@
 
 import pytest
 
+from pip import __version__ as pip_current_version
 from pip._internal import pep425tags
 from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.models.index import PyPI, TestPyPI
@@ -1552,3 +1553,86 @@ def test_target_install_ignores_distutils_config_install_prefix(script):
         (target - script.base_path) in result.files_created and
         (prefix - script.base_path) not in result.files_created
     ), str(result)
+
+
+@pytest.mark.network
+@pytest.mark.skipif("sys.platform != 'win32'")
+@pytest.mark.parametrize('pip_name', [
+    'pip',
+    'pip{}'.format(sys.version_info[0]),
+    'pip{}.{}'.format(*sys.version_info[:2]),
+    'pip.exe',
+    'pip{}.exe'.format(sys.version_info[0]),
+    'pip{}.{}.exe'.format(*sys.version_info[:2])
+])
+def test_protect_pip_from_modification_on_windows(script, pip_name):
+    """
+    Test that pip modification command using ``pip install ...``
+    raises an error on Windows.
+    """
+    command = [pip_name, 'install', 'pip != {}'.format(pip_current_version)]
+    result = script.run(*command, expect_error=True)
+    new_command = [sys.executable, '-m', 'pip'] + command[1:]
+    expected_message = (
+        'To modify pip, please run the following command:\n{}'
+        .format(' '.join(new_command))
+    )
+    assert expected_message in result.stderr, str(result)
+
+
+@pytest.mark.network
+@pytest.mark.skipif("sys.platform != 'win32'")
+def test_protect_pip_from_modification_via_deps_on_windows(script):
+    """
+    Test ``pip install pkga`` raises an error on Windows
+    if `pkga` implicitly tries to upgrade pip.
+    """
+    pkga_wheel_path = create_basic_wheel_for_package(
+        script,
+        'pkga', '0.1',
+        depends=['pip != {}'.format(pip_current_version)],
+    )
+
+    # Make sure pip install pkga raises an error
+    args = ['install', pkga_wheel_path]
+    result = script.pip(*args, expect_error=True, use_module=False)
+    new_command = [sys.executable, '-m', 'pip'] + args
+    expected_message = (
+        'To modify pip, please run the following command:\n{}'
+        .format(' '.join(new_command))
+    )
+    assert expected_message in result.stderr, str(result)
+
+
+@pytest.mark.network
+@pytest.mark.skipif("sys.platform != 'win32'")
+def test_protect_pip_from_modification_via_sub_deps_on_windows(script):
+    """
+    Test ``pip install pkga`` raises an error on Windows
+    if sub-dependencies of `pkga` implicitly tries to upgrade pip.
+    """
+    # Make a wheel for pkga which requires pkgb
+    pkga_wheel_path = create_basic_wheel_for_package(
+        script,
+        'pkga', '0.1',
+        depends=['pkgb'],
+    )
+
+    # Make a wheel for pkgb which requires pip
+    pkgb_wheel_path = create_basic_wheel_for_package(
+        script,
+        'pkgb', '0.1',
+        depends=['pip != {}'.format(pip_current_version)],
+    )
+
+    # Make sure pip install pkga raises an error
+    args = [
+        'install', pkga_wheel_path, '--find-links', pkgb_wheel_path.parent
+    ]
+    result = script.pip(*args, expect_error=True, use_module=False)
+    new_command = [sys.executable, '-m', 'pip'] + args
+    expected_message = (
+        'To modify pip, please run the following command:\n{}'
+        .format(' '.join(new_command))
+    )
+    assert expected_message in result.stderr, str(result)