Start type checking commands/install.py and commands/wheel.py.

src/pip/_internal/commands/install.py

@@ -1,3 +1,10 @@
+
+# The following comment should be removed at some point in the future.
+# It's included for now because without it InstallCommand.run() has a
+# couple errors where we have to know req.name is str rather than
+# Optional[str] for the InstallRequirement req.
+# mypy: strict-optional=False
+
 from __future__ import absolute_import
 
 import errno
@@ -13,7 +20,7 @@ from pip._internal.cache import WheelCache
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.cmdoptions import make_target_python
 from pip._internal.cli.req_command import RequirementCommand
-from pip._internal.cli.status_codes import ERROR
+from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.exceptions import (
     CommandError,
     InstallationError,
@@ -30,9 +37,17 @@ from pip._internal.utils.misc import (
     protect_pip_from_modification_on_windows,
 )
 from pip._internal.utils.temp_dir import TempDirectory
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.virtualenv import virtualenv_no_global
 from pip._internal.wheel import WheelBuilder
 
+if MYPY_CHECK_RUNNING:
+    from optparse import Values
+    from typing import Any, List
+
+    from pip._internal.req.req_install import InstallRequirement
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -242,6 +257,7 @@ class InstallCommand(RequirementCommand):
         self.parser.insert_option_group(0, cmd_opts)
 
     def run(self, options, args):
+        # type: (Values, List[Any]) -> int
         cmdoptions.check_install_build_global(options)
         upgrade_strategy = "to-satisfy-only"
         if options.upgrade:
@@ -425,9 +441,11 @@ class InstallCommand(RequirementCommand):
                         except Exception:
                             pass
                         items.append(item)
-                    installed = ' '.join(items)
-                    if installed:
-                        logger.info('Successfully installed %s', installed)
+                    installed_desc = ' '.join(items)
+                    if installed_desc:
+                        logger.info(
+                            'Successfully installed %s', installed_desc,
+                        )
                 except EnvironmentError as error:
                     show_traceback = (self.verbosity >= 1)
 
@@ -450,7 +468,8 @@ class InstallCommand(RequirementCommand):
             self._handle_target_dir(
                 options.target_dir, target_temp_dir, options.upgrade
             )
-        return requirement_set
+
+        return SUCCESS
 
     def _handle_target_dir(self, target_dir, target_temp_dir, upgrade):
         ensure_dir(target_dir)

src/pip/_internal/commands/wheel.py

@@ -11,8 +11,14 @@ from pip._internal.exceptions import CommandError, PreviousBuildDirError
 from pip._internal.req import RequirementSet
 from pip._internal.req.req_tracker import RequirementTracker
 from pip._internal.utils.temp_dir import TempDirectory
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.wheel import WheelBuilder
 
+if MYPY_CHECK_RUNNING:
+    from optparse import Values
+    from typing import Any, List
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -101,6 +107,7 @@ class WheelCommand(RequirementCommand):
         self.parser.insert_option_group(0, cmd_opts)
 
     def run(self, options, args):
+        # type: (Values, List[Any]) -> None
         cmdoptions.check_install_build_global(options)
 
         if options.build_dir: