Fix tox lint run + isort imports. (#114)

28 files changed, 259 insertions, 151 deletions

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 3880d7f..f9f622d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -20,7 +20,7 @@ jobs:
         - ubuntu
         config:
         # [Python version, tox env]
-        - ["3.8",   "lint"]
+        - ["3.9",   "lint"]
         - ["2.7",   "py27"]
         - ["3.5",   "py35"]
         - ["3.6",   "py36"]
@@ -28,12 +28,13 @@ jobs:
         - ["3.8",   "py38"]
         - ["3.9",   "py39"]
         - ["3.10",  "py310"]
-        - ["pypy2", "pypy"]
-        - ["pypy3", "pypy3"]
-        - ["3.8",   "docs"]
-        - ["3.8",   "coverage"]
+        - ["pypy-2.7", "pypy"]
+        - ["pypy-3.7", "pypy3"]
+        - ["3.9",   "docs"]
+        - ["3.9",   "coverage"]
 
     runs-on: ${{ matrix.os }}-latest
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
     name: ${{ matrix.config[1] }}
     steps:
     - uses: actions/checkout@v2
diff --git a/.gitignore b/.gitignore
index c724a76..1f321f5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,4 +28,5 @@ lib64
 log/
 parts/
 pyvenv.cfg
+testing.log
 var/
diff --git a/.meta.toml b/.meta.toml
index 14348a8..2e9b52d 100644
--- a/.meta.toml
+++ b/.meta.toml
@@ -2,7 +2,7 @@
 # https://github.com/zopefoundation/meta/tree/master/config/pure-python
 [meta]
 template = "pure-python"
-commit-id = "cf84a7fa675ab233c640c6208423a700b8cc874d"
+commit-id = "ae61f414cfef4e129d275679c6a76dc67b1a2c11"
 
 [python]
 with-pypy = true
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..31d95f0
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,23 @@
+<!--
+Generated from:
+https://github.com/zopefoundation/meta/tree/master/config/pure-python
+--> 
+# Contributing to zopefoundation projects
+
+The projects under the zopefoundation GitHub organization are open source and
+welcome contributions in different forms:
+
+* bug reports
+* code improvements and bug fixes
+* documentation improvements
+* pull request reviews
+
+For any changes in the repository besides trivial typo fixes you are required
+to sign the contributor agreement. See
+https://www.zope.dev/developer/becoming-a-committer.html for details.
+
+Please visit our [Developer
+Guidelines](https://www.zope.dev/developer/guidelines.html) if you'd like to
+contribute code changes and our [guidelines for reporting
+bugs](https://www.zope.dev/developer/reporting-bugs.html) if you want to file a
+bug report.
diff --git a/MANIFEST.in b/MANIFEST.in
index 421aed6..24cc0f4 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,5 +1,6 @@
 # Generated from:
 # https://github.com/zopefoundation/meta/tree/master/config/pure-python
+include *.md
 include *.rst
 include *.txt
 include buildout.cfg
diff --git a/setup.cfg b/setup.cfg
index 28dd07c..2cc42ae 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -13,3 +13,14 @@ ignore =
     docs/_build/html/_sources/*
     docs/_build/doctest/*
     docs/_static
+
+[isort]
+force_single_line = True
+combine_as_imports = True
+sections = FUTURE,STDLIB,THIRDPARTY,ZOPE,FIRSTPARTY,LOCALFOLDER
+known_third_party = six, docutils, pkg_resources
+known_zope =
+known_first_party =
+default_section = ZOPE
+line_length = 79
+lines_after_imports = 2
diff --git a/setup.py b/setup.py
index 36d39fb..0256e1c 100644
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,9 @@
 """Setup for zope.schema package
 """
 import os
-from setuptools import setup, find_packages
+
+from setuptools import find_packages
+from setuptools import setup
 
 
 def read(*rnames):
diff --git a/src/zope/schema/__init__.py b/src/zope/schema/__init__.py
index 7991016..537f775 100644
--- a/src/zope/schema/__init__.py
+++ b/src/zope/schema/__init__.py
@@ -13,8 +13,10 @@
 ##############################################################################
 """Schema package constructor
 """
+from zope.schema._bootstrapinterfaces import NO_VALUE
 # Field APIs
 from zope.schema._field import ASCII
+from zope.schema._field import URI
 from zope.schema._field import ASCIILine
 from zope.schema._field import Bool
 from zope.schema._field import Bytes
@@ -58,22 +60,18 @@ from zope.schema._field import TextLine
 from zope.schema._field import Time
 from zope.schema._field import Timedelta
 from zope.schema._field import Tuple
-from zope.schema._field import URI
-
 # Schema APIs
-from zope.schema._schema import getFields
-from zope.schema._schema import getFieldsInOrder
 from zope.schema._schema import getFieldNames
 from zope.schema._schema import getFieldNamesInOrder
-from zope.schema._schema import getValidationErrors
+from zope.schema._schema import getFields
+from zope.schema._schema import getFieldsInOrder
 from zope.schema._schema import getSchemaValidationErrors
-
+from zope.schema._schema import getValidationErrors
 # Acessor API
 from zope.schema.accessors import accessors
-
 # Error API
 from zope.schema.interfaces import ValidationError
-from zope.schema._bootstrapinterfaces import NO_VALUE
+
 
 __all__ = [
     'ASCII',
diff --git a/src/zope/schema/_bootstrapfields.py b/src/zope/schema/_bootstrapfields.py
index 760ae3e..e54eb02 100644
--- a/src/zope/schema/_bootstrapfields.py
+++ b/src/zope/schema/_bootstrapfields.py
@@ -23,17 +23,16 @@ import threading
 import unicodedata
 from math import isinf
 
+from zope.event import notify
 from zope.interface import Attribute
-from zope.interface import Invalid
 from zope.interface import Interface
-from zope.interface import providedBy
+from zope.interface import Invalid
 from zope.interface import implementer
+from zope.interface import providedBy
 from zope.interface.interface import InterfaceClass
 from zope.interface.interfaces import IInterface
 from zope.interface.interfaces import IMethod
 
-from zope.event import notify
-
 from zope.schema._bootstrapinterfaces import ConstraintNotSatisfied
 from zope.schema._bootstrapinterfaces import IBeforeObjectAssignedEvent
 from zope.schema._bootstrapinterfaces import IContextAwareDefaultFactory
@@ -41,8 +40,8 @@ from zope.schema._bootstrapinterfaces import IFromBytes
 from zope.schema._bootstrapinterfaces import IFromUnicode
 from zope.schema._bootstrapinterfaces import IValidatable
 from zope.schema._bootstrapinterfaces import NotAContainer
-from zope.schema._bootstrapinterfaces import NotAnIterator
 from zope.schema._bootstrapinterfaces import NotAnInterface
+from zope.schema._bootstrapinterfaces import NotAnIterator
 from zope.schema._bootstrapinterfaces import RequiredMissing
 from zope.schema._bootstrapinterfaces import SchemaNotCorrectlyImplemented
 from zope.schema._bootstrapinterfaces import SchemaNotFullyImplemented
@@ -54,10 +53,9 @@ from zope.schema._bootstrapinterfaces import TooShort
 from zope.schema._bootstrapinterfaces import TooSmall
 from zope.schema._bootstrapinterfaces import ValidationError
 from zope.schema._bootstrapinterfaces import WrongType
-
-from zope.schema._compat import text_type
-from zope.schema._compat import integer_types
 from zope.schema._compat import PY2
+from zope.schema._compat import integer_types
+from zope.schema._compat import text_type
 
 
 class _NotGiven(object):
diff --git a/src/zope/schema/_bootstrapinterfaces.py b/src/zope/schema/_bootstrapinterfaces.py
index 8bddae1..7bf45d5 100644
--- a/src/zope/schema/_bootstrapinterfaces.py
+++ b/src/zope/schema/_bootstrapinterfaces.py
@@ -21,6 +21,7 @@ from zope.interface.interfaces import IInterface
 
 from zope.schema._messageid import _
 
+
 # pylint:disable=inherit-non-class,keyword-arg-before-vararg,
 # pylint:disable=no-self-argument
 
diff --git a/src/zope/schema/_compat.py b/src/zope/schema/_compat.py
index 51a4716..45512a1 100644
--- a/src/zope/schema/_compat.py
+++ b/src/zope/schema/_compat.py
@@ -1,5 +1,6 @@
 import sys
 
+
 PY3 = sys.version_info[0] >= 3
 PY2 = not PY3
 
diff --git a/src/zope/schema/_field.py b/src/zope/schema/_field.py
index c5e8ba1..44f8880 100644
--- a/src/zope/schema/_field.py
+++ b/src/zope/schema/_field.py
@@ -21,21 +21,47 @@ except ImportError:  # pragma: PY2
     # Python 2
     import collections as abc
 
-from datetime import datetime
+import re
 from datetime import date
-from datetime import timedelta
+from datetime import datetime
 from datetime import time
-import re
-
+from datetime import timedelta
 
 from zope.interface import classImplements
 from zope.interface import classImplementsFirst
-from zope.interface import implementer
 from zope.interface import implementedBy
+from zope.interface import implementer
 from zope.interface.interfaces import IInterface
 
-
+from zope.schema._bootstrapfields import Bool
+from zope.schema._bootstrapfields import Complex
+from zope.schema._bootstrapfields import Container  # API import for __init__
+from zope.schema._bootstrapfields import Decimal
+from zope.schema._bootstrapfields import Field
+from zope.schema._bootstrapfields import Int
+from zope.schema._bootstrapfields import Integral
+from zope.schema._bootstrapfields import \
+    InvalidDecimalLiteral  # noqa: reexport
+from zope.schema._bootstrapfields import Iterable
+from zope.schema._bootstrapfields import MinMaxLen
+from zope.schema._bootstrapfields import Number
+from zope.schema._bootstrapfields import Object
+from zope.schema._bootstrapfields import Orderable
+from zope.schema._bootstrapfields import Password
+from zope.schema._bootstrapfields import Rational
+from zope.schema._bootstrapfields import Real
+from zope.schema._bootstrapfields import Text
+from zope.schema._bootstrapfields import TextLine
+from zope.schema._bootstrapfields import _NotGiven
+from zope.schema._compat import PY3
+from zope.schema._compat import binary_type
+from zope.schema._compat import make_binary
+from zope.schema._compat import string_types
+from zope.schema._compat import text_type
+from zope.schema.fieldproperty import FieldProperty
 from zope.schema.interfaces import IASCII
+from zope.schema.interfaces import IURI
+from zope.schema.interfaces import ConstraintNotSatisfied
 from zope.schema.interfaces import IASCIILine
 from zope.schema.interfaces import IBaseVocabulary
 from zope.schema.interfaces import IBool
@@ -57,25 +83,29 @@ from zope.schema.interfaces import IFromBytes
 from zope.schema.interfaces import IFromUnicode
 from zope.schema.interfaces import IFrozenSet
 from zope.schema.interfaces import IId
-from zope.schema.interfaces import IIterable
 from zope.schema.interfaces import IInt
 from zope.schema.interfaces import IIntegral
 from zope.schema.interfaces import IInterfaceField
+from zope.schema.interfaces import IIterable
 from zope.schema.interfaces import IList
-from zope.schema.interfaces import IMinMaxLen
 from zope.schema.interfaces import IMapping
+from zope.schema.interfaces import IMinMaxLen
 from zope.schema.interfaces import IMutableMapping
 from zope.schema.interfaces import IMutableSequence
 from zope.schema.interfaces import INativeString
 from zope.schema.interfaces import INativeStringLine
-from zope.schema.interfaces import IObject
 from zope.schema.interfaces import INumber
+from zope.schema.interfaces import InvalidDottedName
+from zope.schema.interfaces import InvalidId
+from zope.schema.interfaces import InvalidURI
+from zope.schema.interfaces import InvalidValue
+from zope.schema.interfaces import IObject
 from zope.schema.interfaces import IPassword
 from zope.schema.interfaces import IPythonIdentifier
-from zope.schema.interfaces import IReal
 from zope.schema.interfaces import IRational
-from zope.schema.interfaces import ISet
+from zope.schema.interfaces import IReal
 from zope.schema.interfaces import ISequence
+from zope.schema.interfaces import ISet
 from zope.schema.interfaces import ISource
 from zope.schema.interfaces import ISourceText
 from zope.schema.interfaces import IText
@@ -83,49 +113,15 @@ from zope.schema.interfaces import ITextLine
 from zope.schema.interfaces import ITime
 from zope.schema.interfaces import ITimedelta
 from zope.schema.interfaces import ITuple
-from zope.schema.interfaces import IURI
-
+from zope.schema.interfaces import NotAnInterface
+from zope.schema.interfaces import NotUnique
 from zope.schema.interfaces import ValidationError
-from zope.schema.interfaces import InvalidValue
-from zope.schema.interfaces import WrongType
 from zope.schema.interfaces import WrongContainedType
-from zope.schema.interfaces import NotUnique
-from zope.schema.interfaces import NotAnInterface
-from zope.schema.interfaces import InvalidURI
-from zope.schema.interfaces import InvalidId
-from zope.schema.interfaces import InvalidDottedName
-from zope.schema.interfaces import ConstraintNotSatisfied
-
-from zope.schema._bootstrapfields import Field
-from zope.schema._bootstrapfields import Complex
-from zope.schema._bootstrapfields import Container  # API import for __init__
-from zope.schema._bootstrapfields import Iterable
-from zope.schema._bootstrapfields import Orderable
-from zope.schema._bootstrapfields import Text
-from zope.schema._bootstrapfields import TextLine
-from zope.schema._bootstrapfields import Bool
-from zope.schema._bootstrapfields import Int
-from zope.schema._bootstrapfields import Integral
-from zope.schema._bootstrapfields import Number
-from zope.schema._bootstrapfields import InvalidDecimalLiteral  # noqa: reexport
-from zope.schema._bootstrapfields import Decimal
-from zope.schema._bootstrapfields import Password
-from zope.schema._bootstrapfields import Rational
-from zope.schema._bootstrapfields import Real
-from zope.schema._bootstrapfields import MinMaxLen
-from zope.schema._bootstrapfields import _NotGiven
-from zope.schema._bootstrapfields import Object
-from zope.schema.fieldproperty import FieldProperty
-from zope.schema.vocabulary import getVocabularyRegistry
+from zope.schema.interfaces import WrongType
 from zope.schema.vocabulary import SimpleVocabulary
+from zope.schema.vocabulary import getVocabularyRegistry
 
 
-from zope.schema._compat import text_type
-from zope.schema._compat import string_types
-from zope.schema._compat import binary_type
-from zope.schema._compat import PY3
-from zope.schema._compat import make_binary
-
 # Fix up bootstrap field types
 Field.title = FieldProperty(IField['title'])
 Field.description = FieldProperty(IField['description'])
diff --git a/src/zope/schema/_schema.py b/src/zope/schema/_schema.py
index bd9d780..b4010c1 100644
--- a/src/zope/schema/_schema.py
+++ b/src/zope/schema/_schema.py
@@ -14,10 +14,11 @@
 """Schema convenience functions
 """
 
-from zope.schema._bootstrapfields import get_validation_errors
 from zope.schema._bootstrapfields import get_schema_validation_errors
+from zope.schema._bootstrapfields import get_validation_errors
 from zope.schema._bootstrapfields import getFields
 
+
 __all__ = [
     'getFieldNames',
     'getFields',
diff --git a/src/zope/schema/accessors.py b/src/zope/schema/accessors.py
index 257eb7b..1b67e2d 100644
--- a/src/zope/schema/accessors.py
+++ b/src/zope/schema/accessors.py
@@ -34,9 +34,10 @@ Read accessors function as access method specifications and as field
 specifications.  Write accessors are solely method specifications.
 """
 
-from zope.interface import providedBy, implementedBy
-from zope.interface.interface import Method
+from zope.interface import implementedBy
+from zope.interface import providedBy
 from zope.interface.declarations import Declaration
+from zope.interface.interface import Method
 
 
 class FieldReadAccessor(Method):
diff --git a/src/zope/schema/fieldproperty.py b/src/zope/schema/fieldproperty.py
index cf31382..1a9c928 100644
--- a/src/zope/schema/fieldproperty.py
+++ b/src/zope/schema/fieldproperty.py
@@ -14,14 +14,16 @@
 """Computed attributes based on schema fields
 """
 
-from copy import copy
 import sys
+from copy import copy
+
 import zope.schema
-from zope import interface
 from zope import event
+from zope import interface
 from zope.schema import interfaces
 from zope.schema._bootstrapinterfaces import NO_VALUE
 
+
 _marker = object()
 
 
diff --git a/src/zope/schema/interfaces.py b/src/zope/schema/interfaces.py
index 266bd20..809ca19 100644
--- a/src/zope/schema/interfaces.py
+++ b/src/zope/schema/interfaces.py
@@ -20,7 +20,6 @@ from zope.interface import Interface
 from zope.interface.common.mapping import IEnumerableMapping
 from zope.interface.interfaces import IInterface
 
-
 from zope.schema._bootstrapfields import Bool
 from zope.schema._bootstrapfields import Complex
 from zope.schema._bootstrapfields import Decimal
@@ -33,7 +32,6 @@ from zope.schema._bootstrapfields import Rational
 from zope.schema._bootstrapfields import Real
 from zope.schema._bootstrapfields import Text
 from zope.schema._bootstrapfields import TextLine
-
 # Import from _bootstrapinterfaces only because other packages will expect
 # to find these interfaces here.
 from zope.schema._bootstrapinterfaces import ConstraintNotSatisfied
@@ -41,8 +39,8 @@ from zope.schema._bootstrapinterfaces import IBeforeObjectAssignedEvent
 from zope.schema._bootstrapinterfaces import IContextAwareDefaultFactory
 from zope.schema._bootstrapinterfaces import IFromBytes
 from zope.schema._bootstrapinterfaces import IFromUnicode
-from zope.schema._bootstrapinterfaces import IValidatable
 from zope.schema._bootstrapinterfaces import InvalidValue
+from zope.schema._bootstrapinterfaces import IValidatable
 from zope.schema._bootstrapinterfaces import LenOutOfBounds
 from zope.schema._bootstrapinterfaces import NotAContainer
 from zope.schema._bootstrapinterfaces import NotAnInterface
@@ -61,11 +59,10 @@ from zope.schema._bootstrapinterfaces import TooSmall
 from zope.schema._bootstrapinterfaces import ValidationError
 from zope.schema._bootstrapinterfaces import WrongContainedType
 from zope.schema._bootstrapinterfaces import WrongType
-
 from zope.schema._compat import PY3
-
 from zope.schema._messageid import _
 
+
 __all__ = [
     # Exceptions
     'ConstraintNotSatisfied',
@@ -1091,7 +1088,7 @@ class IVocabularyFactory(Interface):
     """
 
     def __call__(context):
-        """The *context* provides a location that the vocabulary can make use of.
+        """The *context* provides a location that vocabulary can make use of.
         """
 
 
diff --git a/src/zope/schema/tests/__init__.py b/src/zope/schema/tests/__init__.py
index f6718f0..46a4c7e 100644
--- a/src/zope/schema/tests/__init__.py
+++ b/src/zope/schema/tests/__init__.py
@@ -3,9 +3,10 @@
 
 import re
 
-from zope.schema._compat import PY3
 from zope.testing import renormalizing
 
+from zope.schema._compat import PY3
+
 
 def _make_transforms(patterns):
     return [(re.compile(pattern), repl) for pattern, repl in patterns]
diff --git a/src/zope/schema/tests/states.py b/src/zope/schema/tests/states.py
index dc3ca70..c7815d5 100644
--- a/src/zope/schema/tests/states.py
+++ b/src/zope/schema/tests/states.py
@@ -15,8 +15,10 @@
 """
 
 from zope.interface import implementer
+
 from zope.schema import interfaces
 
+
 # This table is based on information from the United States Postal Service:
 # http://www.usps.com/ncsc/lookups/abbreviations.html#states
 _states = {
diff --git a/src/zope/schema/tests/test__bootstrapfields.py b/src/zope/schema/tests/test__bootstrapfields.py
index 5994d39..d903ba0 100644
--- a/src/zope/schema/tests/test__bootstrapfields.py
+++ b/src/zope/schema/tests/test__bootstrapfields.py
@@ -13,8 +13,9 @@
 ##############################################################################
 import decimal
 import doctest
-import unittest
 import unicodedata
+import unittest
+
 
 # pylint:disable=protected-access,inherit-non-class,blacklisted-name
 # pylint:disable=attribute-defined-outside-init
@@ -64,8 +65,8 @@ class InterfaceConformanceTestsMixin(object):
         self.assertIs(self._getTargetInterface(), implemented.__sro__[1])
 
     def test_implements_consistent__sro__(self):
-        from zope.interface import ro
         from zope.interface import implementedBy
+        from zope.interface import ro
         __traceback_info__ = implementedBy(self._getTargetClass()).__sro__
         self.assertTrue(
             ro.is_consistent(implementedBy(self._getTargetClass())))
@@ -379,8 +380,9 @@ class DefaultPropertyTests(unittest.TestCase):
 
     def test___get___w_defaultFactory_w_ICAF_w_check(self):
         from zope.interface import directlyProvides
-        from zope.schema._bootstrapinterfaces \
-            import IContextAwareDefaultFactory
+
+        from zope.schema._bootstrapinterfaces import \
+            IContextAwareDefaultFactory
         _checked = []
 
         def _check(inst, value):
@@ -476,7 +478,9 @@ class FieldTests(EqualityTestsMixin,
             """)
         )
 
-        field = self._makeOne(title=u'A title', description=u"""Multiline description.
+        field = self._makeOne(
+            title=u'A title',
+            description=u"""Multiline description.
 
         Some lines have leading whitespace.
 
@@ -506,6 +510,7 @@ class FieldTests(EqualityTestsMixin,
         # The exact value of the description is preserved,
         # allowing for MessageID objects.
         import textwrap
+
         from zope.i18nmessageid import MessageFactory
 
         msg_factory = MessageFactory('zope')
@@ -1225,15 +1230,15 @@ class NumberTests(EqualityTestsMixin,
         return INumber
 
     def test_class_conforms_to_iface(self):
-        from zope.schema._bootstrapinterfaces import IFromUnicode
         from zope.schema._bootstrapinterfaces import IFromBytes
+        from zope.schema._bootstrapinterfaces import IFromUnicode
         verifyClass = super(NumberTests, self).test_class_conforms_to_iface()
         verifyClass(IFromUnicode, self._getTargetClass())
         verifyClass(IFromBytes, self._getTargetClass())
 
     def test_instance_conforms_to_iface(self):
-        from zope.schema._bootstrapinterfaces import IFromUnicode
         from zope.schema._bootstrapinterfaces import IFromBytes
+        from zope.schema._bootstrapinterfaces import IFromUnicode
         verifyObject = (
             super(NumberTests, self).test_instance_conforms_to_iface())
         verifyObject(IFromUnicode, self._makeOne())
@@ -1440,8 +1445,9 @@ class ObjectTests(EqualityTestsMixin,
     def _makeCycles(self):
         from zope.interface import Interface
         from zope.interface import implementer
-        from zope.schema import Object
+
         from zope.schema import List
+        from zope.schema import Object
         from zope.schema._messageid import _
 
         class IUnit(Interface):
@@ -1486,11 +1492,13 @@ class ObjectTests(EqualityTestsMixin,
 
     def test_class_conforms_to_IObject(self):
         from zope.interface.verify import verifyClass
+
         from zope.schema.interfaces import IObject
         verifyClass(IObject, self._getTargetClass())
 
     def test_instance_conforms_to_IObject(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import IObject
         verifyObject(IObject, self._makeOne())
 
@@ -1514,8 +1522,8 @@ class ObjectTests(EqualityTestsMixin,
         objf.validate(object())  # doesn't raise
 
     def test__validate_w_value_not_providing_schema(self):
-        from zope.schema.interfaces import SchemaNotProvided
         from zope.schema._bootstrapfields import Text
+        from zope.schema.interfaces import SchemaNotProvided
         schema = self._makeSchema(foo=Text(), bar=Text())
         objf = self._makeOne(schema)
         bad_value = object()
@@ -1529,9 +1537,10 @@ class ObjectTests(EqualityTestsMixin,
 
     def test__validate_w_value_providing_schema_but_missing_fields(self):
         from zope.interface import implementer
-        from zope.schema.interfaces import SchemaNotFullyImplemented
-        from zope.schema.interfaces import SchemaNotCorrectlyImplemented
+
         from zope.schema._bootstrapfields import Text
+        from zope.schema.interfaces import SchemaNotCorrectlyImplemented
+        from zope.schema.interfaces import SchemaNotFullyImplemented
         schema = self._makeSchema(foo=Text(), bar=Text())
 
         @implementer(schema)
@@ -1576,11 +1585,12 @@ class ObjectTests(EqualityTestsMixin,
 
     def test__validate_w_value_providing_schema_but_invalid_fields(self):
         from zope.interface import implementer
-        from zope.schema.interfaces import SchemaNotCorrectlyImplemented
-        from zope.schema.interfaces import RequiredMissing
-        from zope.schema.interfaces import WrongType
+
         from zope.schema._bootstrapfields import Text
         from zope.schema._compat import text_type
+        from zope.schema.interfaces import RequiredMissing
+        from zope.schema.interfaces import SchemaNotCorrectlyImplemented
+        from zope.schema.interfaces import WrongType
         schema = self._makeSchema(foo=Text(), bar=Text())
 
         @implementer(schema)
@@ -1617,6 +1627,7 @@ class ObjectTests(EqualityTestsMixin,
 
     def test__validate_w_value_providing_schema(self):
         from zope.interface import implementer
+
         from zope.schema._bootstrapfields import Text
         from zope.schema._field import Choice
 
@@ -1691,9 +1702,10 @@ class ObjectTests(EqualityTestsMixin,
     def test_set_emits_IBOAE(self):
         from zope.event import subscribers
         from zope.interface import implementer
-        from zope.schema.interfaces import IBeforeObjectAssignedEvent
+
         from zope.schema._bootstrapfields import Text
         from zope.schema._field import Choice
+        from zope.schema.interfaces import IBeforeObjectAssignedEvent
 
         schema = self._makeSchema(
             foo=Text(),
@@ -1722,6 +1734,7 @@ class ObjectTests(EqualityTestsMixin,
     def test_set_allows_IBOAE_subscr_to_replace_value(self):
         from zope.event import subscribers
         from zope.interface import implementer
+
         from zope.schema._bootstrapfields import Text
         from zope.schema._field import Choice
 
@@ -1756,12 +1769,13 @@ class ObjectTests(EqualityTestsMixin,
         self.assertEqual(log[-1].context, inst)
 
     def test_validates_invariants_by_default(self):
-        from zope.interface import invariant
         from zope.interface import Interface
-        from zope.interface import implementer
         from zope.interface import Invalid
-        from zope.schema import Text
+        from zope.interface import implementer
+        from zope.interface import invariant
+
         from zope.schema import Bytes
+        from zope.schema import Text
 
         class ISchema(Interface):
 
@@ -1840,15 +1854,18 @@ class ObjectTests(EqualityTestsMixin,
 
     def test_bound_field_of_collection_with_choice(self):
         # https://github.com/zopefoundation/zope.schema/issues/17
-        from zope.interface import Interface, implementer
         from zope.interface import Attribute
+        from zope.interface import Interface
+        from zope.interface import implementer
 
-        from zope.schema import Choice, Object, Set
+        from zope.schema import Choice
+        from zope.schema import Object
+        from zope.schema import Set
         from zope.schema.fieldproperty import FieldProperty
-        from zope.schema.interfaces import IContextSourceBinder
-        from zope.schema.interfaces import WrongContainedType
         from zope.schema.interfaces import ConstraintNotSatisfied
+        from zope.schema.interfaces import IContextSourceBinder
         from zope.schema.interfaces import SchemaNotCorrectlyImplemented
+        from zope.schema.interfaces import WrongContainedType
         from zope.schema.vocabulary import SimpleVocabulary
 
         @implementer(IContextSourceBinder)
@@ -1946,8 +1963,9 @@ class DummyInst(object):
 
 
 def test_suite():
-    import zope.schema._bootstrapfields
     from zope.testing.renormalizing import IGNORE_EXCEPTION_MODULE_IN_PYTHON2
+
+    import zope.schema._bootstrapfields
     suite = unittest.defaultTestLoader.loadTestsFromName(__name__)
     suite.addTests(doctest.DocTestSuite(
         zope.schema._bootstrapfields,
diff --git a/src/zope/schema/tests/test__bootstrapinterfaces.py b/src/zope/schema/tests/test__bootstrapinterfaces.py
index 385fa1c..f7bdc56 100644
--- a/src/zope/schema/tests/test__bootstrapinterfaces.py
+++ b/src/zope/schema/tests/test__bootstrapinterfaces.py
@@ -13,6 +13,7 @@
 ##############################################################################
 import unittest
 
+
 try:
     compare = cmp
 except NameError:
diff --git a/src/zope/schema/tests/test__field.py b/src/zope/schema/tests/test__field.py
index e7864a5..5f25bb5 100644
--- a/src/zope/schema/tests/test__field.py
+++ b/src/zope/schema/tests/test__field.py
@@ -17,11 +17,11 @@ import unittest
 
 from zope.schema.tests.test__bootstrapfields import EqualityTestsMixin
 from zope.schema.tests.test__bootstrapfields import LenTestsMixin
+from zope.schema.tests.test__bootstrapfields import NumberTests
 from zope.schema.tests.test__bootstrapfields import OrderableMissingValueMixin
 from zope.schema.tests.test__bootstrapfields import OrderableTestsMixin
 from zope.schema.tests.test__bootstrapfields import WrongTypeTestsMixin
 
-from zope.schema.tests.test__bootstrapfields import NumberTests
 
 # pylint:disable=protected-access
 # pylint:disable=too-many-lines
@@ -43,8 +43,8 @@ class BytesTests(EqualityTestsMixin,
         return IBytes
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_validate_wrong_types(self):
@@ -160,8 +160,8 @@ class BytesLineTests(EqualityTestsMixin,
         return IBytesLine
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_validate_wrong_types(self):
@@ -440,6 +440,7 @@ class TimedeltaTests(OrderableMissingValueMixin,
 
     def test_validate_required(self):
         from datetime import timedelta
+
         from zope.schema.interfaces import RequiredMissing
         field = self._makeOne()
         field.validate(timedelta(minutes=15))
@@ -477,6 +478,7 @@ class TimeTests(OrderableMissingValueMixin,
 
     def test_validate_required(self):
         from datetime import time
+
         from zope.schema.interfaces import RequiredMissing
         field = self._makeOne()
         field.validate(time(12, 15, 37))
@@ -585,8 +587,9 @@ class ChoiceTests(EqualityTestsMixin,
 
     def test_bind_w_voc_not_ICSB(self):
         from zope.interface import implementer
-        from zope.schema.interfaces import ISource
+
         from zope.schema.interfaces import IBaseVocabulary
+        from zope.schema.interfaces import ISource
 
         @implementer(IBaseVocabulary)
         @implementer(ISource)
@@ -601,6 +604,7 @@ class ChoiceTests(EqualityTestsMixin,
 
     def test_bind_w_voc_is_ICSB(self):
         from zope.interface import implementer
+
         from zope.schema.interfaces import IContextSourceBinder
         from zope.schema.interfaces import ISource
 
@@ -623,6 +627,7 @@ class ChoiceTests(EqualityTestsMixin,
 
     def test_bind_w_voc_is_ICSB_but_not_ISource(self):
         from zope.interface import implementer
+
         from zope.schema.interfaces import IContextSourceBinder
 
         @implementer(IContextSourceBinder)
@@ -750,6 +755,7 @@ class ChoiceTests(EqualityTestsMixin,
 
     def test__validate_source_is_ICSB_unbound(self):
         from zope.interface import implementer
+
         from zope.schema.interfaces import IContextSourceBinder
 
         @implementer(IContextSourceBinder)
@@ -762,8 +768,9 @@ class ChoiceTests(EqualityTestsMixin,
 
     def test__validate_source_is_ICSB_bound(self):
         from zope.interface import implementer
-        from zope.schema.interfaces import IContextSourceBinder
+
         from zope.schema.interfaces import ConstraintNotSatisfied
+        from zope.schema.interfaces import IContextSourceBinder
         from zope.schema.tests.test_vocabulary import _makeSampleVocabulary
 
         @implementer(IContextSourceBinder)
@@ -795,8 +802,8 @@ class URITests(EqualityTestsMixin,
         return IURI
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_validate_wrong_types(self):
@@ -868,8 +875,8 @@ class PythonIdentifierTests(EqualityTestsMixin,
         return PythonIdentifier
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def _getTargetInterface(self):
@@ -917,8 +924,8 @@ class DottedNameTests(EqualityTestsMixin,
         return IDottedName
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_ctor_defaults(self):
@@ -1042,8 +1049,8 @@ class IdTests(EqualityTestsMixin,
         return IId
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_validate_wrong_types(self):
@@ -1127,9 +1134,10 @@ class InterfaceFieldTests(EqualityTestsMixin,
         return IInterfaceField
 
     def test_validate_wrong_types(self):
-        from zope.interface.interfaces import IInterface
         from datetime import date
 
+        from zope.interface.interfaces import IInterface
+
         field = self._makeOne()
         self.assertAllRaiseWrongType(
             field,
@@ -1158,6 +1166,7 @@ class InterfaceFieldTests(EqualityTestsMixin,
 
     def test_validate_required(self):
         from zope.interface import Interface
+
         from zope.schema.interfaces import RequiredMissing
 
         class DummyInterface(Interface):
@@ -1258,9 +1267,9 @@ class CollectionTests(EqualityTestsMixin,
         self.assertEqual(bound.unique, True)
 
     def test__validate_wrong_contained_type(self):
+        from zope.schema._bootstrapfields import Text
         from zope.schema.interfaces import WrongContainedType
         from zope.schema.interfaces import WrongType
-        from zope.schema._bootstrapfields import Text
         text = Text()
         absc = self._makeOne(text)
         with self.assertRaises(WrongContainedType) as exc:
@@ -1275,9 +1284,9 @@ class CollectionTests(EqualityTestsMixin,
         self.assertIs(wct.errors[0].expected_type, text._type)
 
     def test__validate_miss_uniqueness(self):
+        from zope.schema._bootstrapfields import Text
         from zope.schema.interfaces import NotUnique
         from zope.schema.interfaces import WrongType
-        from zope.schema._bootstrapfields import Text
 
         text = Text()
         absc = self._makeOne(text, True)
@@ -1568,9 +1577,9 @@ class MappingTests(EqualityTestsMixin,
         self.assertRaises(RequiredMissing, field.validate, None)
 
     def test_validate_invalid_key_type(self):
+        from zope.schema._bootstrapfields import Int
         from zope.schema.interfaces import WrongContainedType
         from zope.schema.interfaces import WrongType
-        from zope.schema._bootstrapfields import Int
         field = self._makeOne(key_type=Int())
         field.validate({})
         field.validate({1: 'b', 2: 'd'})
@@ -1587,9 +1596,9 @@ class MappingTests(EqualityTestsMixin,
         self.assertIs(field.key_type._type, wct.errors[0].expected_type)
 
     def test_validate_invalid_value_type(self):
+        from zope.schema._bootstrapfields import Int
         from zope.schema.interfaces import WrongContainedType
         from zope.schema.interfaces import WrongType
-        from zope.schema._bootstrapfields import Int
         field = self._makeOne(value_type=Int())
         field.validate({})
         field.validate({'b': 1, 'd': 2})
@@ -1727,8 +1736,8 @@ class NativeStringTests(EqualityTestsMixin,
         return INativeString
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_fromBytes(self):
@@ -1756,8 +1765,8 @@ class NativeStringLineTests(EqualityTestsMixin,
         return INativeStringLine
 
     def _getTargetInterfaces(self):
-        from zope.schema.interfaces import IFromUnicode
         from zope.schema.interfaces import IFromBytes
+        from zope.schema.interfaces import IFromUnicode
         return [self._getTargetInterface(), IFromUnicode, IFromBytes]
 
     def test_fromBytes(self):
@@ -1790,6 +1799,7 @@ class StrippedNativeStringLineTests(NativeStringLineTests):
 
 def _makeSampleVocabulary():
     from zope.interface import implementer
+
     from zope.schema.interfaces import IVocabulary
 
     @implementer(IVocabulary)
diff --git a/src/zope/schema/tests/test_accessors.py b/src/zope/schema/tests/test_accessors.py
index 74bd0a2..531fe47 100644
--- a/src/zope/schema/tests/test_accessors.py
+++ b/src/zope/schema/tests/test_accessors.py
@@ -15,6 +15,7 @@
 """
 import unittest
 
+
 # pylint:disable=inherit-non-class
 
 
@@ -41,6 +42,7 @@ class FieldReadAccessorTests(unittest.TestCase):
 
     def test_ctor_created_inside_interface(self):
         from zope.interface import Interface
+
         from zope.schema import Text
 
         field = Text(title=u'Hmm')
@@ -63,6 +65,7 @@ class FieldReadAccessorTests(unittest.TestCase):
         from zope.interface import providedBy
         from zope.interface.interfaces import IAttribute
         from zope.interface.interfaces import IMethod
+
         from zope.schema import Text
 
         # When wrapping a field that provides stuff,
@@ -170,6 +173,7 @@ class FieldReadAccessorTests(unittest.TestCase):
 
     def test_set_readonly(self):
         from zope.interface import Interface
+
         from zope.schema import Text
         field = Text(readonly=True)
 
@@ -257,6 +261,7 @@ class FieldWriteAccessorTests(unittest.TestCase):
 
     def test_ctor_created_inside_interface(self):
         from zope.interface import Interface
+
         from zope.schema import Text
 
         field = Text(title=u'Hmm')
@@ -290,6 +295,7 @@ class Test_accessors(unittest.TestCase):
 
     def test_w_only_read_accessor(self):
         from zope.interface import Interface
+
         from zope.schema import Text
 
         field = Text(title=u'Hmm', readonly=True)
@@ -310,6 +316,7 @@ class Test_accessors(unittest.TestCase):
 
     def test_w_read_and_write_accessors(self):
         from zope.interface import Interface
+
         from zope.schema import Text
 
         field = Text(title=u'Hmm')
diff --git a/src/zope/schema/tests/test_fieldproperty.py b/src/zope/schema/tests/test_fieldproperty.py
index d5d090b..492d258 100644
--- a/src/zope/schema/tests/test_fieldproperty.py
+++ b/src/zope/schema/tests/test_fieldproperty.py
@@ -266,11 +266,12 @@ class FieldPropertyTests(_Base, _Integration):
         self.assertEqual(_validated, ['123'])
 
     def test_field_event(self):
-        from zope.schema import Text
-        from zope.interface.verify import verifyObject
         from zope.event import subscribers
-        from zope.schema.interfaces import IFieldUpdatedEvent
+        from zope.interface.verify import verifyObject
+
+        from zope.schema import Text
         from zope.schema.fieldproperty import FieldUpdatedEvent
+        from zope.schema.interfaces import IFieldUpdatedEvent
         log = []
         subscribers.append(log.append)
         self.assertEqual(log, [])
@@ -300,11 +301,12 @@ class FieldPropertyTests(_Base, _Integration):
         self.assertEqual(event.object, marker)
 
     def test_field_event_update(self):
-        from zope.schema import Text
-        from zope.interface.verify import verifyObject
         from zope.event import subscribers
-        from zope.schema.interfaces import IFieldUpdatedEvent
+        from zope.interface.verify import verifyObject
+
+        from zope.schema import Text
         from zope.schema.fieldproperty import FieldUpdatedEvent
+        from zope.schema.interfaces import IFieldUpdatedEvent
         field = Text(
             __name__='testing',
             description=u'DESCRIPTION',
@@ -588,9 +590,9 @@ class FieldPropertyStoredThroughFieldTests(_Base, _Integration):
         self.assertRaises(ValueError, setattr, foo, 'testing', '123')
 
     def test_field_event_update(self):
-        from zope.schema import Text
-
         from zope.event import subscribers
+
+        from zope.schema import Text
         from zope.schema.fieldproperty import FieldUpdatedEvent
         field = Text(
             __name__='testing',
@@ -619,9 +621,9 @@ class FieldPropertyStoredThroughFieldTests(_Base, _Integration):
     def test_field_event(self):
         # fieldproperties are everywhere including in field themselfs
         # so event are triggered
-        from zope.schema import Text
-
         from zope.event import subscribers
+
+        from zope.schema import Text
         from zope.schema.fieldproperty import FieldUpdatedEvent
         log = []
         subscribers.append(log.append)
@@ -648,6 +650,7 @@ class FieldPropertyStoredThroughFieldTests(_Base, _Integration):
 
 def _getSchema():
     from zope.interface import Interface
+
     from zope.schema import Bytes
     from zope.schema import Float
     from zope.schema import Text
@@ -666,8 +669,8 @@ class CreateFieldPropertiesTests(unittest.TestCase):
     """Testing ..fieldproperty.createFieldProperties."""
 
     def test_creates_fieldproperties_on_class(self):
-        from zope.schema.fieldproperty import createFieldProperties
         from zope.schema.fieldproperty import FieldProperty
+        from zope.schema.fieldproperty import createFieldProperties
         schema = _getSchema()
 
         class Dummy(object):
diff --git a/src/zope/schema/tests/test_interfaces.py b/src/zope/schema/tests/test_interfaces.py
index ecfb561..249776f 100644
--- a/src/zope/schema/tests/test_interfaces.py
+++ b/src/zope/schema/tests/test_interfaces.py
@@ -22,11 +22,11 @@ class Test__is_field(unittest.TestCase):
         self.assertEqual(self._callFUT(object()), False)
 
     def test_w_normal_fields(self):
-        from zope.schema import Text
         from zope.schema import Bytes
-        from zope.schema import Int
-        from zope.schema import Float
         from zope.schema import Decimal
+        from zope.schema import Float
+        from zope.schema import Int
+        from zope.schema import Text
         self.assertEqual(self._callFUT(Text()), True)
         self.assertEqual(self._callFUT(Bytes()), True)
         self.assertEqual(self._callFUT(Int()), True)
@@ -35,6 +35,7 @@ class Test__is_field(unittest.TestCase):
 
     def test_w_explicitly_provided(self):
         from zope.interface import directlyProvides
+
         from zope.schema.interfaces import IField
 
         class Foo(object):
@@ -62,11 +63,11 @@ class Test__fields(unittest.TestCase):
         self.assertEqual(self._callFUT([object()]), False)
 
     def test_w_fields(self):
-        from zope.schema import Text
         from zope.schema import Bytes
-        from zope.schema import Int
-        from zope.schema import Float
         from zope.schema import Decimal
+        from zope.schema import Float
+        from zope.schema import Int
+        from zope.schema import Text
         self.assertEqual(self._callFUT([Text()]), True)
         self.assertEqual(self._callFUT([Bytes()]), True)
         self.assertEqual(self._callFUT([Int()]), True)
@@ -78,11 +79,11 @@ class Test__fields(unittest.TestCase):
         )
 
     def test_w_mixed(self):
-        from zope.schema import Text
         from zope.schema import Bytes
-        from zope.schema import Int
-        from zope.schema import Float
         from zope.schema import Decimal
+        from zope.schema import Float
+        from zope.schema import Int
+        from zope.schema import Text
         self.assertEqual(self._callFUT([Text(), 0]), False)
         self.assertEqual(
             self._callFUT([Text(), Bytes(), Int(), Float(), Decimal(), 0]),
@@ -93,6 +94,7 @@ class Test__fields(unittest.TestCase):
         """If class Bool is used as a schema itself, it must not be required.
         """
         from zope.schema.interfaces import IBool
+
         # treat IBool as schema with fields
         field = IBool.get("required")
         self.assertFalse(field.required)
@@ -101,6 +103,7 @@ class Test__fields(unittest.TestCase):
         """If class Bool is used as a schema itself, it must default to False
         """
         from zope.schema.interfaces import IBool
+
         # treat IBool as schema with fields
         field = IBool.get("default")
         self.assertFalse(field.default)
diff --git a/src/zope/schema/tests/test_schema.py b/src/zope/schema/tests/test_schema.py
index e19dfeb..6172abe 100644
--- a/src/zope/schema/tests/test_schema.py
+++ b/src/zope/schema/tests/test_schema.py
@@ -19,6 +19,7 @@ import unittest
 def _makeSchema():
 
     from zope.interface import Interface
+
     from zope.schema import Bytes
 
     class ISchemaTest(Interface):
@@ -160,6 +161,7 @@ class Test_getValidationErrors(unittest.TestCase):
 
     def test_schema_with_field_errors(self):
         from zope.interface import Interface
+
         from zope.schema import Text
         from zope.schema.interfaces import SchemaNotFullyImplemented
 
@@ -209,8 +211,8 @@ class Test_getSchemaValidationErrors(unittest.TestCase):
         return getSchemaValidationErrors(schema, object)
 
     def test_schema_wo_fields(self):
-        from zope.interface import Interface
         from zope.interface import Attribute
+        from zope.interface import Interface
 
         class INoFields(Interface):
             def method():
@@ -222,6 +224,7 @@ class Test_getSchemaValidationErrors(unittest.TestCase):
 
     def test_schema_with_fields_ok(self):
         from zope.interface import Interface
+
         from zope.schema import Text
 
         class IWithFields(Interface):
@@ -237,6 +240,7 @@ class Test_getSchemaValidationErrors(unittest.TestCase):
 
     def test_schema_with_missing_field(self):
         from zope.interface import Interface
+
         from zope.schema import Text
         from zope.schema.interfaces import SchemaNotFullyImplemented
 
@@ -253,6 +257,7 @@ class Test_getSchemaValidationErrors(unittest.TestCase):
 
     def test_schema_with_invalid_field(self):
         from zope.interface import Interface
+
         from zope.schema import Int
         from zope.schema.interfaces import TooSmall
 
diff --git a/src/zope/schema/tests/test_states.py b/src/zope/schema/tests/test_states.py
index 7b81cc1..bc1d7a5 100644
--- a/src/zope/schema/tests/test_states.py
+++ b/src/zope/schema/tests/test_states.py
@@ -19,9 +19,9 @@ import unittest
 class StateSelectionTest(unittest.TestCase):
 
     def setUp(self):
+        from zope.schema.tests.states import StateVocabulary
         from zope.schema.vocabulary import _clear
         from zope.schema.vocabulary import getVocabularyRegistry
-        from zope.schema.tests.states import StateVocabulary
         _clear()
         vr = getVocabularyRegistry()
         vr.register("states", StateVocabulary)
@@ -33,6 +33,7 @@ class StateSelectionTest(unittest.TestCase):
     def _makeSchema(self):
 
         from zope.interface import Interface
+
         from zope.schema import Choice
         from zope.schema.tests.states import StateVocabulary
 
@@ -63,6 +64,7 @@ class StateSelectionTest(unittest.TestCase):
 
     def test_default_presentation(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import IVocabulary
         schema = self._makeSchema()
         field = schema.getDescriptionFor("state1")
@@ -72,6 +74,7 @@ class StateSelectionTest(unittest.TestCase):
 
     def test_contains(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import IVocabulary
         from zope.schema.tests.states import StateVocabulary
         vocab = StateVocabulary()
@@ -91,6 +94,7 @@ class StateSelectionTest(unittest.TestCase):
 
     def test_prebound_vocabulary(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import IVocabulary
         schema = self._makeSchema()
         field = schema.getDescriptionFor("state3")
diff --git a/src/zope/schema/tests/test_vocabulary.py b/src/zope/schema/tests/test_vocabulary.py
index eef246b..24383df 100644
--- a/src/zope/schema/tests/test_vocabulary.py
+++ b/src/zope/schema/tests/test_vocabulary.py
@@ -27,11 +27,13 @@ class SimpleTermTests(unittest.TestCase):
 
     def test_class_conforms_to_ITokenizedTerm(self):
         from zope.interface.verify import verifyClass
+
         from zope.schema.interfaces import ITokenizedTerm
         verifyClass(ITokenizedTerm, self._getTargetClass())
 
     def test_instance_conforms_to_ITokenizedTerm(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import ITokenizedTerm
         verifyObject(ITokenizedTerm, self._makeOne('VALUE'))
 
@@ -116,16 +118,19 @@ class SimpleVocabularyTests(unittest.TestCase):
 
     def test_class_conforms_to_IVocabularyTokenized(self):
         from zope.interface.verify import verifyClass
+
         from zope.schema.interfaces import IVocabularyTokenized
         verifyClass(IVocabularyTokenized, self._getTargetClass())
 
     def test_instance_conforms_to_IVocabularyTokenized(self):
         from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import IVocabularyTokenized
         verifyObject(IVocabularyTokenized, self._makeOne(()))
 
     def test_ctor_additional_interfaces(self):
         from zope.interface import Interface
+
         from zope.schema.vocabulary import SimpleTerm
 
         class IStupid(Interface):
@@ -146,6 +151,7 @@ class SimpleVocabularyTests(unittest.TestCase):
 
     def test_fromValues(self):
         from zope.interface import Interface
+
         from zope.schema.interfaces import ITokenizedTerm
 
         class IStupid(Interface):
@@ -162,6 +168,7 @@ class SimpleVocabularyTests(unittest.TestCase):
 
     def test_fromItems(self):
         from zope.interface import Interface
+
         from zope.schema.interfaces import ITokenizedTerm
 
         class IStupid(Interface):
@@ -179,6 +186,7 @@ class SimpleVocabularyTests(unittest.TestCase):
 
     def test_fromItems_triples(self):
         from zope.interface import Interface
+
         from zope.schema.interfaces import ITitledTokenizedTerm
 
         class IStupid(Interface):
@@ -363,8 +371,9 @@ class TreeVocabularyTests(unittest.TestCase):
             self.assertTrue(ITitledTokenizedTerm.providedBy(term))
 
     def test_implementation(self):
-        from zope.interface.verify import verifyObject
         from zope.interface.common.mapping import IEnumerableMapping
+        from zope.interface.verify import verifyObject
+
         from zope.schema.interfaces import ITreeVocabulary
         from zope.schema.interfaces import IVocabulary
         from zope.schema.interfaces import IVocabularyTokenized
@@ -689,8 +698,8 @@ class RegistryTests(unittest.TestCase):
         _clear()
 
     def test_setVocabularyRegistry(self):
-        from zope.schema.vocabulary import setVocabularyRegistry
         from zope.schema.vocabulary import getVocabularyRegistry
+        from zope.schema.vocabulary import setVocabularyRegistry
         r = _makeDummyRegistry()
         setVocabularyRegistry(r)
         self.assertTrue(getVocabularyRegistry() is r)
@@ -706,6 +715,7 @@ class RegistryTests(unittest.TestCase):
 
 def _makeSampleVocabulary():
     from zope.interface import implementer
+
     from zope.schema.interfaces import IVocabulary
 
     class SampleTerm(object):
diff --git a/tox.ini b/tox.ini
index 099c616..5addfe0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -29,15 +29,25 @@ extras =
 [testenv:lint]
 basepython = python3
 skip_install = true
+commands =
+    isort --check-only --diff {toxinidir}/src {toxinidir}/setup.py
+    flake8 src setup.py
+    check-manifest
+    check-python-versions
 deps =
-    flake8
     check-manifest
     check-python-versions >= 0.19.1
     wheel
+    flake8
+    isort
+
+[testenv:isort-apply]
+basepython = python3
+commands_pre =
+deps =
+    isort
 commands =
-    flake8 src setup.py
-    check-manifest
-    check-python-versions
+    isort {toxinidir}/src {toxinidir}/setup.py []
 
 [testenv:docs]
 basepython = python3