ensure single import per line

This adds the very small plugin flake8-import-single which
will prevent us from having an import with more than one symbol
on a line.

Flake8 by itself prevents this pattern with E401:

import collections, os, sys

However does not do anything with this:

from sqlalchemy import Column, text

Both statements have the same issues generating merge artifacts
as well as presenting a manual decision to be made.   While
zimports generally cleans up such imports at the top level, we
don't enforce zimports / pre-commit use.

the plugin finds the same issue for imports that are inside of
test methods.   We shouldn't usually have imports in test methods
so most of them here are moved to be top level.

The version is pinned at 0.1.5; the project seems to have no
activity since 2019, however there are three 0.1.6dev releases
on pypi which stopped in September 2019, they seem to be
experiments with packaging.  The source for 0.1.5
is extremely simple and only reveals one method to flake8
(the run() method).

Change-Id: Icea894e43bad9c0b5d4feb5f49c6c666d6ea6aa1

1 files changed, 6 insertions, 6 deletions

diff --git a/test/aaa_profiling/test_memusage.py b/test/aaa_profiling/test_memusage.py
index d30ccb3b8..9b2cb31be 100644
--- a/test/aaa_profiling/test_memusage.py
+++ b/test/aaa_profiling/test_memusage.py
@@ -6,6 +6,7 @@ import pickle
 import weakref
 
 import sqlalchemy as sa
+from sqlalchemy import and_
 from sqlalchemy import ForeignKey
 from sqlalchemy import func
 from sqlalchemy import inspect
@@ -14,8 +15,12 @@ from sqlalchemy import MetaData
 from sqlalchemy import select
 from sqlalchemy import String
 from sqlalchemy import testing
+from sqlalchemy import types
 from sqlalchemy import Unicode
 from sqlalchemy import util
+from sqlalchemy.dialects import mysql
+from sqlalchemy.dialects import postgresql
+from sqlalchemy.dialects import sqlite
 from sqlalchemy.engine import result
 from sqlalchemy.engine.processors import to_decimal_processor_factory
 from sqlalchemy.orm import aliased
@@ -34,6 +39,7 @@ from sqlalchemy.orm import subqueryload
 from sqlalchemy.orm.session import _sessions
 from sqlalchemy.sql import column
 from sqlalchemy.sql import util as sql_util
+from sqlalchemy.sql.util import visit_binary_product
 from sqlalchemy.sql.visitors import cloned_traverse
 from sqlalchemy.sql.visitors import replacement_traverse
 from sqlalchemy.testing import engines
@@ -310,9 +316,6 @@ class MemUsageTest(EnsureZeroed):
         """test storage of bind processors, result processors
         in dialect-wide registry."""
 
-        from sqlalchemy.dialects import mysql, postgresql, sqlite
-        from sqlalchemy import types
-
         eng = engines.testing_engine()
         for args in (
             (types.Integer, {}),
@@ -1669,9 +1672,6 @@ class CycleTest(_fixtures.FixtureTest):
     def test_visit_binary_product(self):
         a, b, q, e, f, j, r = (column(chr_) for chr_ in "abqefjr")
 
-        from sqlalchemy import and_, func
-        from sqlalchemy.sql.util import visit_binary_product
-
         expr = and_((a + b) == q + func.sum(e + f), j == r)
 
         def visit(expr, left, right):