confirming dependencies when uninstall package

news/4245.feature

@@ -0,0 +1 @@
+added confirming dependencies to ``uninstall`` command.

src/pip/_internal/commands/uninstall.py

@@ -5,6 +5,7 @@
 from pip._internal.basecommand import Command
 from pip._internal.exceptions import InstallationError
 from pip._internal.req import InstallRequirement, parse_requirements
+from pip._internal.utils.misc import confirm_dependencies
 
 
 class UninstallCommand(Command):
@@ -64,6 +65,8 @@ def run(self, options, args):
                     '"pip help %(name)s")' % dict(name=self.name)
                 )
             for req in reqs_to_uninstall.values():
+                if not (options.yes or confirm_dependencies(req)):
+                    continue
                 req.uninstall(
                     auto_confirm=options.yes, verbose=options.verbose != 0
                 )

src/pip/_internal/utils/misc.py

@@ -877,3 +877,19 @@ def enum(*sequential, **named):
     reverse = dict((value, key) for key, value in enums.items())
     enums['reverse_mapping'] = reverse
     return type('Enum', (), enums)
+
+
+def confirm_dependencies(req):
+    installed_distributions = get_installed_distributions()
+    dep_keys = set()
+    for dist in installed_distributions:
+        dep_keys.update(
+            [dist for d in dist.requires() if d.key == req.req.name])
+    if not dep_keys:
+        return True
+    logger.info(("The following packages depend on %s "
+                 "and may break if it is uninstalled:") % req.req)
+    for dep in dep_keys:
+        logger.info(dep)
+    response = ask('Proceed (y/n)? ', ('y', 'n'))
+    return response == 'y'

tests/unit/test_utils.py

@@ -14,11 +14,13 @@
 
 import pytest
 from mock import Mock, patch
+from pip._vendor.packaging.requirements import Requirement
 from pip._vendor.six import BytesIO
 
 from pip._internal.exceptions import (
     HashMismatch, HashMissing, InstallationError, UnsupportedPythonVersion
 )
+from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.encoding import auto_decode
 from pip._internal.utils.glibc import check_glibc_version
 from pip._internal.utils.hashes import Hashes, MissingHashes
@@ -594,6 +596,41 @@ def test_check_requires(self, metadata, should_raise):
             check_dist_requires_python(fake_dist)
 
 
+@pytest.mark.parametrize(
+    "installed_requires,confirm_answer",
+    [
+        ((), None),
+        (("dummy",), 'y'),
+        pytest.mark.xfail((("dummy",), 'n')),
+    ],
+)
+def test_confirm_dependencies(installed_requires, confirm_answer):
+    from pip._internal.utils.misc import confirm_dependencies
+    patch_target = 'pip._internal.utils.misc.get_installed_distributions'
+    with patch(patch_target) as mock_gid:
+        with patch('pip._internal.utils.misc.ask') as mock_ask:
+            mock_ask.return_value = confirm_answer
+
+            class req(Requirement):
+                def __init__(self, key):
+                    self.key = key
+
+            class installed(object):
+
+                def __init__(self, requires):
+                    self._requires = [req(r) for r in requires]
+
+                def requires(self):
+                    return self._requires
+
+            requirement = InstallRequirement(Requirement("dummy"), None)
+            installed_packages = [installed(installed_requires)]
+            mock_gid.return_value = installed_packages
+            assert confirm_dependencies(requirement)
+            if confirm_answer:
+                mock_ask.assert_called_with('Proceed (y/n)? ', ('y', 'n'))
+
+
 class TestGetProg(object):
 
     @pytest.mark.parametrize(