Add mypy annotations to pip._internal.commands.check

src/pip/_internal/commands/__init__.py

@@ -4,6 +4,10 @@ Package containing all pip commands
 
 # The following comment should be removed at some point in the future.
 # mypy: disallow-untyped-defs=False
+# There is currently a bug in python/typeshed mentioned at
+# https://github.com/python/typeshed/issues/3906 which causes the
+# return type of difflib.get_close_matches to be reported
+# as List[Sequence[str]] whereas it should have been List[str]
 
 from __future__ import absolute_import
 

src/pip/_internal/commands/check.py

@@ -1,17 +1,20 @@
-# The following comment should be removed at some point in the future.
-# mypy: disallow-untyped-defs=False
-
 import logging
 
 from pip._internal.cli.base_command import Command
+from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.operations.check import (
     check_package_set,
     create_package_set_from_installed,
 )
 from pip._internal.utils.misc import write_output
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 logger = logging.getLogger(__name__)
 
+if MYPY_CHECK_RUNNING:
+    from typing import List, Any
+    from optparse import Values
+
 
 class CheckCommand(Command):
     """Verify installed packages have compatible dependencies."""
@@ -20,6 +23,8 @@ class CheckCommand(Command):
       %prog [options]"""
 
     def run(self, options, args):
+        # type: (Values, List[Any]) -> int
+
         package_set, parsing_probs = create_package_set_from_installed()
         missing, conflicting = check_package_set(package_set)
 
@@ -40,6 +45,7 @@ class CheckCommand(Command):
                 )
 
         if missing or conflicting or parsing_probs:
-            return 1
+            return ERROR
         else:
             write_output("No broken requirements found.")
+            return SUCCESS