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

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 304db477f765e6983f313f7a11cb40d508724dc1..c4397b96a950ef2fd2e4898da8d23e1cce0add46 100644 (file)
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -19,6 +19,7 @@ repos:
     -   id: flake8
         additional_dependencies:
           - flake8-import-order
+          - flake8-import-single==0.1.5
           - flake8-builtins
           - flake8-docstrings
           - flake8-rst-docstrings

diff --git a/alembic/testing/env.py b/alembic/testing/env.py
index 3d42f1cb4b885947755dbfeb62899e759a392dbf..79a4980f49b2e5f330885733cc2a6d4fefa19881 100644 (file)
--- a/alembic/testing/env.py
+++ b/alembic/testing/env.py
@@ -7,6 +7,8 @@ from sqlalchemy.testing import config
 from sqlalchemy.testing import provision
 
 from . import util as testing_util
+from .. import command
+from .. import script
 from .. import util
 from ..script import Script
 from ..script import ScriptDirectory
@@ -20,7 +22,6 @@ def _get_staging_directory():
 
 
 def staging_env(create=True, template="generic", sourceless=False):
-    from alembic import command, script
 
     cfg = _testing_config()
     if create:

diff --git a/tests/test_autogen_render.py b/tests/test_autogen_render.py
index f138df5fcc3d881287373a46ad9aa5574decad16..ada2a12372fee932638fce8826eff86d03a04d34 100644 (file)
--- a/tests/test_autogen_render.py
+++ b/tests/test_autogen_render.py
@@ -25,6 +25,7 @@ from sqlalchemy import text
 from sqlalchemy import types
 from sqlalchemy import Unicode
 from sqlalchemy import UniqueConstraint
+from sqlalchemy import VARCHAR
 from sqlalchemy.engine.default import DefaultDialect
 from sqlalchemy.sql import and_
 from sqlalchemy.sql import column
@@ -1792,7 +1793,6 @@ class AutogenRenderTest(TestBase):
         )
 
     def test_render_variant(self):
-        from sqlalchemy import VARCHAR, CHAR
 
         self.autogen_context.opts["user_module_prefix"] = None
 
@@ -1824,8 +1824,6 @@ class AutogenRenderTest(TestBase):
         )
 
     def test_repr_user_type_user_prefix_present(self):
-        from sqlalchemy.types import UserDefinedType
-
         class MyType(UserDefinedType):
             def get_col_spec(self):
                 return "MYTYPE"

diff --git a/tests/test_op.py b/tests/test_op.py
index 5682abb8e7968952f7601ac78002f8358089b128..c483c4a8b9261c4e4ffe157d4220c1b17a15103b 100644 (file)
--- a/tests/test_op.py
+++ b/tests/test_op.py
@@ -14,10 +14,13 @@ from sqlalchemy import Table
 from sqlalchemy import UniqueConstraint
 from sqlalchemy.sql import column
 from sqlalchemy.sql import func
+from sqlalchemy.sql import table
 from sqlalchemy.sql import text
 from sqlalchemy.sql.schema import quoted_name
 
 from alembic import op
+from alembic.operations import MigrateOperation
+from alembic.operations import Operations
 from alembic.operations import ops
 from alembic.operations import schemaobj
 from alembic.testing import assert_raises_message
@@ -1023,8 +1026,6 @@ class OpTest(TestBase):
 
     def test_inline_literal(self):
         context = op_fixture()
-        from sqlalchemy.sql import table, column
-        from sqlalchemy import String, Integer
 
         account = table(
             "account", column("name", String), column("id", Integer)
@@ -1144,8 +1145,6 @@ class OpTest(TestBase):
 class SQLModeOpTest(TestBase):
     def test_auto_literals(self):
         context = op_fixture(as_sql=True, literal_binds=True)
-        from sqlalchemy.sql import table, column
-        from sqlalchemy import String, Integer
 
         account = table(
             "account", column("name", String), column("id", Integer)
@@ -1179,8 +1178,6 @@ class SQLModeOpTest(TestBase):
 
 class CustomOpTest(TestBase):
     def test_custom_op(self):
-        from alembic.operations import Operations, MigrateOperation
-
         @Operations.register_operation("create_sequence")
         class CreateSequenceOp(MigrateOperation):
             """Create a SEQUENCE."""

diff --git a/tests/test_postgresql.py b/tests/test_postgresql.py
index 6a67e0be867bf9b93ba20639bab54ff326b4fc1d..23d6a8c0798c3b8a281fb903a73fd58fca46a25f 100644 (file)
--- a/tests/test_postgresql.py
+++ b/tests/test_postgresql.py
@@ -19,9 +19,11 @@ from sqlalchemy import types
 from sqlalchemy import UniqueConstraint
 from sqlalchemy.dialects.postgresql import ARRAY
 from sqlalchemy.dialects.postgresql import BYTEA
+from sqlalchemy.dialects.postgresql import ExcludeConstraint
 from sqlalchemy.dialects.postgresql import HSTORE
 from sqlalchemy.dialects.postgresql import JSON
 from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.dialects.postgresql import TSRANGE
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.sql import column
 from sqlalchemy.sql import false
@@ -1248,7 +1250,6 @@ class PGUniqueIndexAutogenerateTest(AutogenFixtureTest, TestBase):
 
     @config.requirements.btree_gist
     def test_exclude_const_unchanged(self):
-        from sqlalchemy.dialects.postgresql import TSRANGE, ExcludeConstraint
 
         m1 = MetaData()
         m2 = MetaData()

diff --git a/tests/test_script_production.py b/tests/test_script_production.py
index bedf545d9d2f9b41c865ccbf709164a8e60cf8ef..5c4cd9eb04fd458e8ff8b0352dde13bac410d48f 100644 (file)
--- a/tests/test_script_production.py
+++ b/tests/test_script_production.py
@@ -5,7 +5,10 @@ from unittest.mock import patch
 
 from dateutil import tz
 import sqlalchemy as sa
+from sqlalchemy import Column
 from sqlalchemy import inspect
+from sqlalchemy import MetaData
+from sqlalchemy import Table
 
 from alembic import autogenerate
 from alembic import command
@@ -717,7 +720,6 @@ class ImportsTest(TestBase):
         )
 
     def test_imports_in_script(self):
-        from sqlalchemy import MetaData, Table, Column
         from sqlalchemy.dialects.mysql import VARCHAR
 
         type_ = VARCHAR(20, charset="utf8", national=True)

diff --git a/tox.ini b/tox.ini
index 8b744d7c6fdcd542bc7a7bfd576926377d8ba85b..08cc4f4350db42d84327d9149bdab031ed15205f 100644 (file)
--- a/tox.ini
+++ b/tox.ini
@@ -90,6 +90,7 @@ basepython = python3
 deps=
       flake8
       flake8-import-order
+      flake8-import-single==0.1.5
       flake8-builtins
       flake8-docstrings
       flake8-rst-docstrings