Remove redundant import alias

This patch remove redundant import aliases and add pep8 hacking function
to check no redundant import aliases.

Co-Authored-By: Dao Cong Tien <tiendc@vn.fujitsu.com>

Change-Id: I3207cb9f0eb4b4a029b7e822b9c59cf48d1e0f9d
Closes-Bug: #1745527

watcher/hacking/checks.py

@@ -60,6 +60,7 @@ log_warn = re.compile(
     r"(.)*LOG\.(warn)\(\s*('|\"|_)")
 unittest_imports_dot = re.compile(r"\bimport[\s]+unittest\b")
 unittest_imports_from = re.compile(r"\bfrom[\s]+unittest\b")
+re_redundant_import_alias = re.compile(r".*import (.+) as \1$")
 
 
 @flake8ext
@@ -271,6 +272,18 @@ def check_builtins_gettext(logical_line, tokens, filename, lines, noqa):
             yield (0, msg)
 
 
+@flake8ext
+def no_redundant_import_alias(logical_line):
+    """Checking no redundant import alias.
+
+    https://bugs.launchpad.net/watcher/+bug/1745527
+
+    N342
+    """
+    if re.match(re_redundant_import_alias, logical_line):
+        yield(0, "N342: No redundant import alias.")
+
+
 def factory(register):
     register(use_jsonutils)
     register(check_assert_called_once_with)
@@ -286,3 +299,4 @@ def factory(register):
     register(check_log_warn_deprecated)
     register(check_oslo_i18n_wrapper)
     register(check_builtins_gettext)
+    register(no_redundant_import_alias)

watcher/notifications/exception.py

@@ -16,7 +16,7 @@ import sys
 import six
 
 from watcher.notifications import base as notificationbase
-from watcher.objects import base as base
+from watcher.objects import base
 from watcher.objects import fields as wfields