From 8899f8b5b5dfc84e8e0481a5587d0285c6835ec5 Mon Sep 17 00:00:00 2001
From: Eric Fried <openstack@fried.cc>
Date: Fri, 7 Jun 2019 14:17:31 -0500
Subject: Hacking N363: `in (not_a_tuple)`

A few places in the code had conditionals including:

 if something in (element):

which was clearly intended to be

 if something in (element,):

(I.e. `in $tuple`, not `in element` with redundant parens) or just

 if something == element:

Fix those [1] and introduce hacking rule N363 to disallow this kind of
thing in the future.

[1] NOTE: These weren't actually latent bugs because

 'foo' in ('foo')

which is the same as

 'foo' in 'foo'

returns True. In order to be a bug, the left operand would have to be
able to be a substring of the right:

 'foo' in ('foobar')  # True
 'foo' in ('foobar',) # False

...which I don't think is possible in any of the scenarios found.

Change-Id: I950d07eb533e0d43466c58e36b314aaaf8560251
---
 nova/tests/unit/test_hacking.py | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'nova/tests/unit/test_hacking.py')

diff --git a/nova/tests/unit/test_hacking.py b/nova/tests/unit/test_hacking.py
index aa519e91d6..00631e07b5 100644
--- a/nova/tests/unit/test_hacking.py
+++ b/nova/tests/unit/test_hacking.py
@@ -894,3 +894,27 @@ class HackingTestCase(test.NoDBTestCase):
         for filename in (good_filenames + bad_filenames):
             self._assert_has_no_errors(
                 code, checks.privsep_imports_not_aliased, filename=filename)
+
+    def test_did_you_mean_tuple(self):
+        code = """
+                    if foo in (bar):
+                    if foo in ('bar'):
+                    if foo in (path.to.CONST_1234):
+                    if foo in (
+                        bar):
+               """
+        errors = [(x + 1, 0, 'N363') for x in range(4)]
+        self._assert_has_errors(
+            code, checks.did_you_mean_tuple, expected_errors=errors)
+        code = """
+                    def in(this_would_be_weird):
+                        # A match in (any) comment doesn't count
+                        if foo in (bar,)
+                            or foo in ('bar',)
+                            or foo in ("bar",)
+                            or foo in (set1 + set2)
+                            or foo in ("string continuations "
+                                "are probably okay")
+                            or foo in (method_call_should_this_work()):
+               """
+        self._assert_has_no_errors(code, checks.did_you_mean_tuple)
-- 
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