apply pyupgrade

.pre-commit-config.yaml

@@ -1,22 +1,29 @@
 repos:
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.1.0
+    hooks:
+      - id: pyupgrade
+        args: ["--py36-plus"]
   - repo: https://github.com/asottile/reorder_python_imports
-    rev: v1.5.0
+    rev: v2.1.0
     hooks:
       - id: reorder-python-imports
         name: Reorder Python imports (src, tests)
         files: "^(?!examples/)"
-        args: ["--application-directories", ".:src"]
+        args: ["--application-directories", "src"]
   - repo: https://github.com/python/black
-    rev: 19.3b0
+    rev: 19.10b0
     hooks:
       - id: black
   - repo: https://gitlab.com/pycqa/flake8
-    rev: 3.7.7
+    rev: 3.7.9
     hooks:
       - id: flake8
-        additional_dependencies: [flake8-bugbear]
+        additional_dependencies:
+          - flake8-bugbear
+          - flake8-implicit-str-concat
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.2.3
+    rev: v2.5.0
     hooks:
       - id: check-byte-order-marker
       - id: trailing-whitespace

docs/conf.py

@@ -52,14 +52,12 @@ singlehtml_sidebars = {"index": ["project.html", "localtoc.html"]}
 html_static_path = ["_static"]
 html_favicon = "_static/flask-icon.png"
 html_logo = "_static/flask-icon.png"
-html_title = "Flask Documentation ({})".format(version)
+html_title = f"Flask Documentation ({version})"
 html_show_sourcelink = False
 
 # LaTeX ----------------------------------------------------------------
 
-latex_documents = [
+latex_documents = [(master_doc, f"Flask-{version}.tex", html_title, author, "manual")]
-    (master_doc, "Flask-{}.tex".format(version), html_title, author, "manual")
-]
 
 # Local Extensions -----------------------------------------------------
 
@@ -76,9 +74,9 @@ def github_link(name, rawtext, text, lineno, inliner, options=None, content=None
         words = None
 
     if packaging.version.parse(release).is_devrelease:
-        url = "{0}master/{1}".format(base_url, text)
+        url = f"{base_url}master/{text}"
     else:
-        url = "{0}{1}/{2}".format(base_url, release, text)
+        url = f"{base_url}{release}/{text}"
 
     if words is None:
         words = url

examples/javascript/js_example/__init__.py

@@ -2,4 +2,4 @@ from flask import Flask
 
 app = Flask(__name__)
 
-from js_example import views
+from js_example import views  # noqa: F401

examples/javascript/js_example/views.py

@@ -8,7 +8,7 @@ from js_example import app
 @app.route("/", defaults={"js": "plain"})
 @app.route("/<any(plain, jquery, fetch):js>")
 def index(js):
-    return render_template("{0}.html".format(js), js=js)
+    return render_template(f"{js}.html", js=js)
 
 
 @app.route("/add", methods=["POST"])

examples/javascript/setup.py

@@ -1,9 +1,7 @@
-import io
-
 from setuptools import find_packages
 from setuptools import setup
 
-with io.open("README.rst", "rt", encoding="utf8") as f:
+with open("README.rst", encoding="utf8") as f:
     readme = f.read()
 
 setup(

examples/tutorial/flaskr/auth.py

@@ -64,7 +64,7 @@ def register():
             db.execute("SELECT id FROM user WHERE username = ?", (username,)).fetchone()
             is not None
         ):
-            error = "User {0} is already registered.".format(username)
+            error = f"User {username} is already registered."
 
         if error is None:
             # the name is available, store it in the database and go to

examples/tutorial/flaskr/blog.py

@@ -49,7 +49,7 @@ def get_post(id, check_author=True):
     )
 
     if post is None:
-        abort(404, "Post id {0} doesn't exist.".format(id))
+        abort(404, f"Post id {id} doesn't exist.")
 
     if check_author and post["author_id"] != g.user["id"]:
         abort(403)

examples/tutorial/setup.py

@@ -1,9 +1,7 @@
-import io
-
 from setuptools import find_packages
 from setuptools import setup
 
-with io.open("README.rst", "rt", encoding="utf8") as f:
+with open("README.rst", encoding="utf8") as f:
     readme = f.read()
 
 setup(

examples/tutorial/tests/conftest.py

@@ -44,7 +44,7 @@ def runner(app):
     return app.test_cli_runner()
 
 
-class AuthActions(object):
+class AuthActions:
     def __init__(self, client):
         self._client = client
 

examples/tutorial/tests/test_db.py

@@ -17,7 +17,7 @@ def test_get_close_db(app):
 
 
 def test_init_db_command(runner, monkeypatch):
-    class Recorder(object):
+    class Recorder:
         called = False
 
     def fake_init_db():

setup.cfg

@@ -20,7 +20,8 @@ source =
 # F = flake8 pyflakes
 # W = pycodestyle warnings
 # B9 = bugbear opinions
-select = B, E, F, W, B9
+# ISC = implicit-str-concat
+select = B, E, F, W, B9, ISC
 ignore =
     # slice notation whitespace, invalid
     E203
@@ -35,6 +36,5 @@ ignore =
 # up to 88 allowed by bugbear B950
 max-line-length = 80
 per-file-ignores =
-    # __init__ modules export names
+    # __init__ module exports names
-    **/__init__.py: F401
+    src/flask/__init__.py: F401
-    src/flask/_compat.py: E731, B301, F401

setup.py

@@ -1,13 +1,12 @@
-import io
 import re
 
 from setuptools import find_packages
 from setuptools import setup
 
-with io.open("README.rst", "rt", encoding="utf8") as f:
+with open("README.rst", encoding="utf8") as f:
     readme = f.read()
 
-with io.open("src/flask/__init__.py", "rt", encoding="utf8") as f:
+with open("src/flask/__init__.py", encoding="utf8") as f:
     version = re.search(r'__version__ = "(.*?)"', f.read()).group(1)
 
 setup(

src/flask/__init__.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask
     ~~~~~

src/flask/__main__.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.__main__
     ~~~~~~~~~~~~~~

src/flask/app.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.app
     ~~~~~~~~~
@@ -1111,7 +1110,7 @@ class Flask(_PackageBoundObject):
         endpoint=None,
         view_func=None,
         provide_automatic_options=None,
-        **options
+        **options,
     ):
         """Connects a URL rule.  Works exactly like the :meth:`route`
         decorator.  If a view_func is provided it will be registered with the
@@ -1180,7 +1179,7 @@ class Flask(_PackageBoundObject):
                 "Allowed methods must be a list of strings, for"
                 ' example: @app.route(..., methods=["POST"])'
             )
-        methods = set(item.upper() for item in methods)
+        methods = {item.upper() for item in methods}
 
         # Methods that should always be added
         required_methods = set(getattr(view_func, "required_methods", ()))
@@ -1342,7 +1341,7 @@ class Flask(_PackageBoundObject):
         """
         if isinstance(code_or_exception, HTTPException):  # old broken behavior
             raise ValueError(
-                "Tried to register a handler for an exception instance {0!r}."
+                "Tried to register a handler for an exception instance {!r}."
                 " Handlers can only be registered for exception classes or"
                 " HTTP error codes.".format(code_or_exception)
             )
@@ -1351,7 +1350,7 @@ class Flask(_PackageBoundObject):
             exc_class, code = self._get_exc_class_and_code(code_or_exception)
         except KeyError:
             raise KeyError(
-                "'{0}' is not a recognized HTTP error code. Use a subclass of"
+                "'{}' is not a recognized HTTP error code. Use a subclass of"
                 " HTTPException with that code instead.".format(code_or_exception)
             )
 
@@ -1811,7 +1810,7 @@ class Flask(_PackageBoundObject):
         .. versionadded:: 0.8
         """
         self.logger.error(
-            "Exception on %s [%s]" % (request.path, request.method), exc_info=exc_info
+            f"Exception on {request.path} [{request.method}]", exc_info=exc_info
         )
 
     def raise_routing_exception(self, request):
@@ -2376,4 +2375,4 @@ class Flask(_PackageBoundObject):
         return self.wsgi_app(environ, start_response)
 
     def __repr__(self):
-        return "<%s %r>" % (self.__class__.__name__, self.name)
+        return f"<{self.__class__.__name__} {self.name!r}>"

src/flask/blueprints.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.blueprints
     ~~~~~~~~~~~~~~~~
@@ -18,7 +17,7 @@ from .helpers import _PackageBoundObject
 _sentinel = object()
 
 
-class BlueprintSetupState(object):
+class BlueprintSetupState:
     """Temporary holder object for registering a blueprint with the
     application.  An instance of this class is created by the
     :meth:`~flask.Blueprint.make_setup_state` method and later passed
@@ -80,10 +79,10 @@ class BlueprintSetupState(object):
             defaults = dict(defaults, **options.pop("defaults"))
         self.app.add_url_rule(
             rule,
-            "%s.%s" % (self.blueprint.name, endpoint),
+            f"{self.blueprint.name}.{endpoint}",
             view_func,
             defaults=defaults,
-            **options
+            **options,
         )
 
 

src/flask/cli.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.cli
     ~~~~~~~~~
@@ -8,8 +7,6 @@
     :copyright: 2010 Pallets
     :license: BSD-3-Clause
 """
-from __future__ import print_function
-
 import ast
 import inspect
 import os
@@ -167,7 +164,7 @@ def find_app_by_string(script_info, module, app_name):
     if inspect.isfunction(attr):
         if args:
             try:
-                args = ast.literal_eval("({args},)".format(args=args))
+                args = ast.literal_eval(f"({args},)")
             except (ValueError, SyntaxError) as e:
                 raise NoAppException(
                     "Could not parse the arguments in "
@@ -243,7 +240,7 @@ def locate_app(script_info, module_name, app_name, raise_if_not_found=True):
                 "\n\n{tb}".format(name=module_name, tb=traceback.format_exc())
             )
         elif raise_if_not_found:
-            raise NoAppException('Could not import "{name}".'.format(name=module_name))
+            raise NoAppException(f'Could not import "{module_name}".')
         else:
             return
 
@@ -285,7 +282,7 @@ version_option = click.Option(
 )
 
 
-class DispatchingApp(object):
+class DispatchingApp:
     """Special application that dispatches to a Flask application which
     is imported by name in a background thread.  If an error happens
     it is recorded and shown as part of the WSGI handling which in case
@@ -344,7 +341,7 @@ class DispatchingApp(object):
             return rv(environ, start_response)
 
 
-class ScriptInfo(object):
+class ScriptInfo:
     """Helper object to deal with Flask applications.  This is usually not
     necessary to interface with as it's used internally in the dispatching
     to click.  In future versions of Flask this object will most likely play
@@ -491,7 +488,7 @@ class FlaskGroup(AppGroup):
         add_version_option=True,
         load_dotenv=True,
         set_debug_flag=True,
-        **extra
+        **extra,
     ):
         params = list(extra.pop("params", None) or ())
 
@@ -583,7 +580,7 @@ class FlaskGroup(AppGroup):
 
         kwargs["obj"] = obj
         kwargs.setdefault("auto_envvar_prefix", "FLASK")
-        return super(FlaskGroup, self).main(*args, **kwargs)
+        return super().main(*args, **kwargs)
 
 
 def _path_is_ancestor(path, other):
@@ -662,14 +659,14 @@ def show_server_banner(env, debug, app_import_path, eager_loading):
         return
 
     if app_import_path is not None:
-        message = ' * Serving Flask app "{0}"'.format(app_import_path)
+        message = f' * Serving Flask app "{app_import_path}"'
 
         if not eager_loading:
             message += " (lazy loading)"
 
         click.echo(message)
 
-    click.echo(" * Environment: {0}".format(env))
+    click.echo(f" * Environment: {env}")
 
     if env == "production":
         click.secho(
@@ -680,7 +677,7 @@ def show_server_banner(env, debug, app_import_path, eager_loading):
         click.secho("   Use a production WSGI server instead.", dim=True)
 
     if debug is not None:
-        click.echo(" * Debug mode: {0}".format("on" if debug else "off"))
+        click.echo(" * Debug mode: {}".format("on" if debug else "off"))
 
 
 class CertParamType(click.ParamType):
@@ -766,7 +763,7 @@ class SeparatedPathType(click.Path):
 
     def convert(self, value, param, ctx):
         items = self.split_envvar_value(value)
-        super_convert = super(SeparatedPathType, self).convert
+        super_convert = super().convert
         return [super_convert(item, param, ctx) for item in items]
 
 
@@ -866,12 +863,8 @@ def shell_command():
     from .globals import _app_ctx_stack
 
     app = _app_ctx_stack.top.app
-    banner = "Python %s on %s\nApp: %s [%s]\nInstance: %s" % (
+    banner = "Python {} on {}\nApp: {} [{}]\nInstance: {}".format(
-        sys.version,
+        sys.version, sys.platform, app.import_name, app.env, app.instance_path,
-        sys.platform,
-        app.import_name,
-        app.env,
-        app.instance_path,
     )
     ctx = {}
 
@@ -879,7 +872,7 @@ def shell_command():
     # is using it.
     startup = os.environ.get("PYTHONSTARTUP")
     if startup and os.path.isfile(startup):
-        with open(startup, "r") as f:
+        with open(startup) as f:
             eval(compile(f.read(), startup, "exec"), ctx)
 
     ctx.update(app.make_shell_context())

src/flask/config.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.config
     ~~~~~~~~~~~~
@@ -15,7 +14,7 @@ import types
 from werkzeug.utils import import_string
 
 
-class ConfigAttribute(object):
+class ConfigAttribute:
     """Makes an attribute forward to the config"""
 
     def __init__(self, name, get_converter=None):
@@ -126,7 +125,7 @@ class Config(dict):
         try:
             with open(filename, mode="rb") as config_file:
                 exec(compile(config_file.read(), filename, "exec"), d.__dict__)
-        except IOError as e:
+        except OSError as e:
             if silent and e.errno in (errno.ENOENT, errno.EISDIR, errno.ENOTDIR):
                 return False
             e.strerror = "Unable to load configuration file (%s)" % e.strerror
@@ -197,7 +196,7 @@ class Config(dict):
         try:
             with open(filename) as f:
                 obj = load(f)
-        except IOError as e:
+        except OSError as e:
             if silent and e.errno in (errno.ENOENT, errno.EISDIR):
                 return False
 
@@ -271,4 +270,4 @@ class Config(dict):
         return rv
 
     def __repr__(self):
-        return "<%s %s>" % (self.__class__.__name__, dict.__repr__(self))
+        return "<{} {}>".format(self.__class__.__name__, dict.__repr__(self))

src/flask/ctx.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.ctx
     ~~~~~~~~~
@@ -23,7 +22,7 @@ from .signals import appcontext_pushed
 _sentinel = object()
 
 
-class _AppCtxGlobals(object):
+class _AppCtxGlobals:
     """A plain object. Used as a namespace for storing data during an
     application context.
 
@@ -200,7 +199,7 @@ def has_app_context():
     return _app_ctx_stack.top is not None
 
 
-class AppContext(object):
+class AppContext:
     """The application context binds an application object implicitly
     to the current thread or greenlet, similar to how the
     :class:`RequestContext` binds request information.  The application
@@ -234,7 +233,7 @@ class AppContext(object):
                 self.app.do_teardown_appcontext(exc)
         finally:
             rv = _app_ctx_stack.pop()
-        assert rv is self, "Popped wrong app context.  (%r instead of %r)" % (rv, self)
+        assert rv is self, f"Popped wrong app context.  ({rv!r} instead of {self!r})"
         appcontext_popped.send(self.app)
 
     def __enter__(self):
@@ -245,7 +244,7 @@ class AppContext(object):
         self.pop(exc_value)
 
 
-class RequestContext(object):
+class RequestContext:
     """The request context contains all request relevant information.  It is
     created at the beginning of the request and pushed to the
     `_request_ctx_stack` and removed at the end of it.  It will create the
@@ -420,10 +419,9 @@ class RequestContext(object):
             if app_ctx is not None:
                 app_ctx.pop(exc)
 
-            assert rv is self, "Popped wrong request context. (%r instead of %r)" % (
+            assert (
-                rv,
+                rv is self
-                self,
+            ), f"Popped wrong request context. ({rv!r} instead of {self!r})"
-            )
 
     def auto_pop(self, exc):
         if self.request.environ.get("flask._preserve_context") or (
@@ -447,7 +445,7 @@ class RequestContext(object):
         self.auto_pop(exc_value)
 
     def __repr__(self):
-        return "<%s '%s' [%s] of %s>" % (
+        return "<{} '{}' [{}] of {}>".format(
             self.__class__.__name__,
             self.request.url,
             self.request.method,

src/flask/debughelpers.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.debughelpers
     ~~~~~~~~~~~~~~~~~~
@@ -102,7 +101,7 @@ def attach_enctype_error_multidict(request):
 
 
 def _dump_loader_info(loader):
-    yield "class: %s.%s" % (type(loader).__module__, type(loader).__name__)
+    yield "class: {}.{}".format(type(loader).__module__, type(loader).__name__)
     for key, value in sorted(loader.__dict__.items()):
         if key.startswith("_"):
             continue
@@ -115,7 +114,7 @@ def _dump_loader_info(loader):
             continue
         elif not isinstance(value, (str, int, float, bool)):
             continue
-        yield "%s: %r" % (key, value)
+        yield f"{key}: {value!r}"
 
 
 def explain_template_loading_attempts(app, template, attempts):
@@ -131,7 +130,7 @@ def explain_template_loading_attempts(app, template, attempts):
         if isinstance(srcobj, Flask):
             src_info = 'application "%s"' % srcobj.import_name
         elif isinstance(srcobj, Blueprint):
-            src_info = 'blueprint "%s" (%s)' % (srcobj.name, srcobj.import_name)
+            src_info = f'blueprint "{srcobj.name}" ({srcobj.import_name})'
         else:
             src_info = repr(srcobj)
 

src/flask/globals.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.globals
     ~~~~~~~~~~~~~

src/flask/helpers.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.helpers
     ~~~~~~~~~~~~~
@@ -155,8 +154,7 @@ def stream_with_context(generator_or_function):
             # don't need that because they are closed on their destruction
             # automatically.
             try:
-                for item in gen:
+                yield from gen
-                    yield item
             finally:
                 if hasattr(gen, "close"):
                     gen.close()
@@ -933,7 +931,7 @@ def find_package(import_name):
     return None, package_path
 
 
-class locked_cached_property(object):
+class locked_cached_property:
     """A decorator that converts a function into a lazy property.  The
     function wrapped is called the first time to retrieve the result
     and then that calculated result is used the next time you access
@@ -959,7 +957,7 @@ class locked_cached_property(object):
             return value
 
 
-class _PackageBoundObject(object):
+class _PackageBoundObject:
     #: The name of the package or module that this app belongs to. Do not
     #: change this once it is set by the constructor.
     import_name = None
@@ -1137,7 +1135,7 @@ def is_ip(value):
     for family in (socket.AF_INET, socket.AF_INET6):
         try:
             socket.inet_pton(family, value)
-        except socket.error:
+        except OSError:
             pass
         else:
             return True

src/flask/json/__init__.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 flask.json
 ~~~~~~~~~~
@@ -286,10 +285,10 @@ def htmlsafe_dumps(obj, **kwargs):
     """
     rv = (
         dumps(obj, **kwargs)
-        .replace(u"<", u"\\u003c")
+        .replace("<", "\\u003c")
-        .replace(u">", u"\\u003e")
+        .replace(">", "\\u003e")
-        .replace(u"&", u"\\u0026")
+        .replace("&", "\\u0026")
-        .replace(u"'", u"\\u0027")
+        .replace("'", "\\u0027")
     )
     if not _slash_escape:
         rv = rv.replace("\\/", "/")

src/flask/json/tag.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Tagged JSON
 ~~~~~~~~~~~
@@ -54,7 +53,7 @@ from ..json import dumps
 from ..json import loads
 
 
-class JSONTag(object):
+class JSONTag:
     """Base class for defining type tags for :class:`TaggedJSONSerializer`."""
 
     __slots__ = ("serializer",)
@@ -122,7 +121,7 @@ class PassDict(JSONTag):
     def to_json(self, value):
         # JSON objects may only have string keys, so don't bother tagging the
         # key here.
-        return dict((k, self.serializer.tag(v)) for k, v in value.items())
+        return {k: self.serializer.tag(v) for k, v in value.items()}
 
     tag = to_json
 
@@ -213,7 +212,7 @@ class TagDateTime(JSONTag):
         return parse_date(value)
 
 
-class TaggedJSONSerializer(object):
+class TaggedJSONSerializer:
     """Serializer that uses a tag system to compactly represent objects that
     are not JSON types. Passed as the intermediate serializer to
     :class:`itsdangerous.Serializer`.
@@ -269,7 +268,7 @@ class TaggedJSONSerializer(object):
 
         if key is not None:
             if not force and key in self.tags:
-                raise KeyError("Tag '{0}' is already registered.".format(key))
+                raise KeyError(f"Tag '{key}' is already registered.")
 
             self.tags[key] = tag
 

src/flask/logging.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 flask.logging
 ~~~~~~~~~~~~~
@@ -6,8 +5,6 @@ flask.logging
 :copyright: 2010 Pallets
 :license: BSD-3-Clause
 """
-from __future__ import absolute_import
-
 import logging
 import sys
 

src/flask/sessions.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.sessions
     ~~~~~~~~~~~~~~
@@ -77,19 +76,19 @@ class SecureCookieSession(CallbackDict, SessionMixin):
             self.modified = True
             self.accessed = True
 
-        super(SecureCookieSession, self).__init__(initial, on_update)
+        super().__init__(initial, on_update)
 
     def __getitem__(self, key):
         self.accessed = True
-        return super(SecureCookieSession, self).__getitem__(key)
+        return super().__getitem__(key)
 
     def get(self, key, default=None):
         self.accessed = True
-        return super(SecureCookieSession, self).get(key, default)
+        return super().get(key, default)
 
     def setdefault(self, key, default=None):
         self.accessed = True
-        return super(SecureCookieSession, self).setdefault(key, default)
+        return super().setdefault(key, default)
 
 
 class NullSession(SecureCookieSession):
@@ -109,7 +108,7 @@ class NullSession(SecureCookieSession):
     del _fail
 
 
-class SessionInterface(object):
+class SessionInterface:
     """The basic interface you have to implement in order to replace the
     default session interface which uses werkzeug's securecookie
     implementation.  The only methods you have to implement are

src/flask/signals.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.signals
     ~~~~~~~~~~~~~
@@ -16,11 +15,11 @@ try:
 except ImportError:
     signals_available = False
 
-    class Namespace(object):
+    class Namespace:
         def signal(self, name, doc=None):
             return _FakeSignal(name, doc)
 
-    class _FakeSignal(object):
+    class _FakeSignal:
         """If blinker is unavailable, create a fake class with the same
         interface that allows sending of signals but will fail with an
         error on anything else.  Instead of doing anything on send, it

src/flask/templating.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.templating
     ~~~~~~~~~~~~~~~~

src/flask/testing.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.testing
     ~~~~~~~~~~~~~
@@ -51,7 +50,7 @@ class EnvironBuilder(werkzeug.test.EnvironBuilder):
         subdomain=None,
         url_scheme=None,
         *args,
-        **kwargs
+        **kwargs,
     ):
         assert not (base_url or subdomain or url_scheme) or (
             base_url is not None
@@ -64,7 +63,7 @@ class EnvironBuilder(werkzeug.test.EnvironBuilder):
             app_root = app.config["APPLICATION_ROOT"]
 
             if subdomain:
-                http_host = "{0}.{1}".format(subdomain, http_host)
+                http_host = f"{subdomain}.{http_host}"
 
             if url_scheme is None:
                 url_scheme = app.config["PREFERRED_URL_SCHEME"]
@@ -82,7 +81,7 @@ class EnvironBuilder(werkzeug.test.EnvironBuilder):
                 path += sep + url.query
 
         self.app = app
-        super(EnvironBuilder, self).__init__(path, base_url, *args, **kwargs)
+        super().__init__(path, base_url, *args, **kwargs)
 
     def json_dumps(self, obj, **kwargs):
         """Serialize ``obj`` to a JSON-formatted string.
@@ -112,7 +111,7 @@ class FlaskClient(Client):
     preserve_context = False
 
     def __init__(self, *args, **kwargs):
-        super(FlaskClient, self).__init__(*args, **kwargs)
+        super().__init__(*args, **kwargs)
         self.environ_base = {
             "REMOTE_ADDR": "127.0.0.1",
             "HTTP_USER_AGENT": "werkzeug/" + werkzeug.__version__,
@@ -239,7 +238,7 @@ class FlaskCliRunner(CliRunner):
 
     def __init__(self, app, **kwargs):
         self.app = app
-        super(FlaskCliRunner, self).__init__(**kwargs)
+        super().__init__(**kwargs)
 
     def invoke(self, cli=None, args=None, **kwargs):
         """Invokes a CLI command in an isolated environment. See
@@ -262,4 +261,4 @@ class FlaskCliRunner(CliRunner):
         if "obj" not in kwargs:
             kwargs["obj"] = ScriptInfo(create_app=lambda: self.app)
 
-        return super(FlaskCliRunner, self).invoke(cli, args, **kwargs)
+        return super().invoke(cli, args, **kwargs)

src/flask/views.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.views
     ~~~~~~~~~~~
@@ -16,7 +15,7 @@ http_method_funcs = frozenset(
 )
 
 
-class View(object):
+class View:
     """Alternative way to use view functions.  A subclass has to implement
     :meth:`dispatch_request` which is called with the view arguments from
     the URL routing system.  If :attr:`methods` is provided the methods
@@ -113,7 +112,7 @@ class MethodViewType(type):
     """
 
     def __init__(cls, name, bases, d):
-        super(MethodViewType, cls).__init__(name, bases, d)
+        super().__init__(name, bases, d)
 
         if "methods" not in d:
             methods = set()

src/flask/wrappers.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     flask.wrappers
     ~~~~~~~~~~~~~~
@@ -22,7 +21,7 @@ class JSONMixin(_JSONMixin):
 
     def on_json_loading_failed(self, e):
         if current_app and current_app.debug:
-            raise BadRequest("Failed to decode JSON object: {0}".format(e))
+            raise BadRequest(f"Failed to decode JSON object: {e}")
 
         raise BadRequest()
 
@@ -134,4 +133,4 @@ class Response(ResponseBase, JSONMixin):
             return current_app.config["MAX_COOKIE_SIZE"]
 
         # return Werkzeug's default when not in an app context
-        return super(Response, self).max_cookie_size
+        return super().max_cookie_size

tests/conftest.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.conftest
     ~~~~~~~~~~~~~~
@@ -112,7 +111,7 @@ def limit_loader(request, monkeypatch):
     if not request.param:
         return
 
-    class LimitedLoader(object):
+    class LimitedLoader:
         def __init__(self, loader):
             self.loader = loader
 
@@ -172,7 +171,7 @@ def install_egg(modules_tmpdir, monkeypatch):
             textwrap.dedent(
                 """
         from setuptools import setup
-        setup(name='{0}',
+        setup(name='{}',
               version='1.0',
               packages=['site_egg'],
               zip_safe=True)
@@ -187,7 +186,7 @@ def install_egg(modules_tmpdir, monkeypatch):
         subprocess.check_call(
             [sys.executable, "setup.py", "bdist_egg"], cwd=str(modules_tmpdir)
         )
-        egg_path, = modules_tmpdir.join("dist/").listdir()
+        (egg_path,) = modules_tmpdir.join("dist/").listdir()
         monkeypatch.syspath_prepend(str(egg_path))
         return egg_path
 

tests/test_appctx.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.appctx
     ~~~~~~~~~~~~
@@ -163,7 +162,7 @@ def test_app_ctx_globals_methods(app, app_ctx):
 
 
 def test_custom_app_ctx_globals_class(app):
-    class CustomRequestGlobals(object):
+    class CustomRequestGlobals:
         def __init__(self):
             self.spam = "eggs"
 
@@ -190,7 +189,7 @@ def test_context_refcounts(app, client):
                 pass
         env = flask._request_ctx_stack.top.request.environ
         assert env["werkzeug.request"] is not None
-        return u""
+        return ""
 
     res = client.get("/")
     assert res.status_code == 200

tests/test_apps/cliapp/app.py

@@ -1,6 +1,3 @@
-from __future__ import absolute_import
-from __future__ import print_function
-
 from flask import Flask
 
 testapp = Flask("testapp")

tests/test_apps/cliapp/factory.py

@@ -1,6 +1,3 @@
-from __future__ import absolute_import
-from __future__ import print_function
-
 from flask import Flask
 
 

tests/test_apps/cliapp/importerrorapp.py

@@ -1,6 +1,3 @@
-from __future__ import absolute_import
-from __future__ import print_function
-
 from flask import Flask
 
 raise ImportError()

tests/test_apps/cliapp/multiapp.py

@@ -1,6 +1,3 @@
-from __future__ import absolute_import
-from __future__ import print_function
-
 from flask import Flask
 
 app1 = Flask("app1")

tests/test_basic.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.basic
     ~~~~~~~~~~~~~~~~~~~~~
@@ -278,7 +277,7 @@ def test_session_using_server_name_port_and_path(app, client):
 
 
 def test_session_using_application_root(app, client):
-    class PrefixPathMiddleware(object):
+    class PrefixPathMiddleware:
         def __init__(self, app, prefix):
             self.app = app
             self.prefix = prefix
@@ -583,18 +582,18 @@ def test_extended_flashing(app):
 
     @app.route("/")
     def index():
-        flask.flash(u"Hello World")
+        flask.flash("Hello World")
-        flask.flash(u"Hello World", "error")
+        flask.flash("Hello World", "error")
-        flask.flash(flask.Markup(u"<em>Testing</em>"), "warning")
+        flask.flash(flask.Markup("<em>Testing</em>"), "warning")
         return ""
 
     @app.route("/test/")
     def test():
         messages = flask.get_flashed_messages()
         assert list(messages) == [
-            u"Hello World",
+            "Hello World",
-            u"Hello World",
+            "Hello World",
-            flask.Markup(u"<em>Testing</em>"),
+            flask.Markup("<em>Testing</em>"),
         ]
         return ""
 
@@ -603,9 +602,9 @@ def test_extended_flashing(app):
         messages = flask.get_flashed_messages(with_categories=True)
         assert len(messages) == 3
         assert list(messages) == [
-            ("message", u"Hello World"),
+            ("message", "Hello World"),
-            ("error", u"Hello World"),
+            ("error", "Hello World"),
-            ("warning", flask.Markup(u"<em>Testing</em>")),
+            ("warning", flask.Markup("<em>Testing</em>")),
         ]
         return ""
 
@@ -614,7 +613,7 @@ def test_extended_flashing(app):
         messages = flask.get_flashed_messages(
             category_filter=["message"], with_categories=True
         )
-        assert list(messages) == [("message", u"Hello World")]
+        assert list(messages) == [("message", "Hello World")]
         return ""
 
     @app.route("/test_filters/")
@@ -623,8 +622,8 @@ def test_extended_flashing(app):
             category_filter=["message", "warning"], with_categories=True
         )
         assert list(messages) == [
-            ("message", u"Hello World"),
+            ("message", "Hello World"),
-            ("warning", flask.Markup(u"<em>Testing</em>")),
+            ("warning", flask.Markup("<em>Testing</em>")),
         ]
         return ""
 
@@ -632,8 +631,8 @@ def test_extended_flashing(app):
     def test_filters2():
         messages = flask.get_flashed_messages(category_filter=["message", "warning"])
         assert len(messages) == 2
-        assert messages[0] == u"Hello World"
+        assert messages[0] == "Hello World"
-        assert messages[1] == flask.Markup(u"<em>Testing</em>")
+        assert messages[1] == flask.Markup("<em>Testing</em>")
         return ""
 
     # Create new test client on each test to clean flashed messages.
@@ -1102,11 +1101,11 @@ def test_enctype_debug_helper(app, client):
 def test_response_types(app, client):
     @app.route("/text")
     def from_text():
-        return u"Hällo Wörld"
+        return "Hällo Wörld"
 
     @app.route("/bytes")
     def from_bytes():
-        return u"Hällo Wörld".encode("utf-8")
+        return "Hällo Wörld".encode()
 
     @app.route("/full_tuple")
     def from_full_tuple():
@@ -1143,8 +1142,8 @@ def test_response_types(app, client):
     def from_dict():
         return {"foo": "bar"}, 201
 
-    assert client.get("/text").data == u"Hällo Wörld".encode("utf-8")
+    assert client.get("/text").data == "Hällo Wörld".encode()
-    assert client.get("/bytes").data == u"Hällo Wörld".encode("utf-8")
+    assert client.get("/bytes").data == "Hällo Wörld".encode()
 
     rv = client.get("/full_tuple")
     assert rv.data == b"Meh"
@@ -1611,11 +1610,11 @@ def test_inject_blueprint_url_defaults(app):
 
 
 def test_nonascii_pathinfo(app, client):
-    @app.route(u"/киртест")
+    @app.route("/киртест")
     def index():
         return "Hello World!"
 
-    rv = client.get(u"/киртест")
+    rv = client.get("/киртест")
     assert rv.data == b"Hello World!"
 
 
@@ -1875,7 +1874,7 @@ def test_multi_route_rules(app, client):
 
 
 def test_multi_route_class_views(app, client):
-    class View(object):
+    class View:
         def __init__(self, app):
             app.add_url_rule("/", "index", self.index)
             app.add_url_rule("/<test>/", "index", self.index)
@@ -1907,12 +1906,12 @@ def test_run_server_port(monkeypatch, app):
 
     # Mocks werkzeug.serving.run_simple method
     def run_simple_mock(hostname, port, application, *args, **kwargs):
-        rv["result"] = "running on %s:%s ..." % (hostname, port)
+        rv["result"] = f"running on {hostname}:{port} ..."
 
     monkeypatch.setattr(werkzeug.serving, "run_simple", run_simple_mock)
     hostname, port = "localhost", 8000
     app.run(hostname, port, debug=True)
-    assert rv["result"] == "running on %s:%s ..." % (hostname, port)
+    assert rv["result"] == f"running on {hostname}:{port} ..."
 
 
 @pytest.mark.parametrize(

tests/test_blueprints.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.blueprints
     ~~~~~~~~~~~~~~~~

tests/test_cli.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.test_cli
     ~~~~~~~~~~~~~~
@@ -8,8 +7,6 @@
 """
 # This file was part of Flask-CLI and was modified under the terms of
 # its Revised BSD License. Copyright © 2015 CERN.
-from __future__ import absolute_import
-
 import os
 import ssl
 import sys
@@ -261,7 +258,7 @@ def test_get_version(test_apps, capsys):
     from werkzeug import __version__ as werkzeug_version
     from platform import python_version
 
-    class MockCtx(object):
+    class MockCtx:
         resilient_parsing = False
         color = None
 

tests/test_config.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.test_config
     ~~~~~~~~~~~~~~~~~
@@ -65,7 +64,7 @@ def test_config_from_mapping():
 
 
 def test_config_from_class():
-    class Base(object):
+    class Base:
         TEST_KEY = "foo"
 
     class Test(Base):
@@ -186,8 +185,8 @@ def test_from_pyfile_weird_encoding(tmpdir, encoding):
     f = tmpdir.join("my_config.py")
     f.write_binary(
         textwrap.dedent(
-            u"""
+            """
-    # -*- coding: {0} -*-
+    # -*- coding: {} -*-
     TEST_VALUE = "föö"
     """.format(
                 encoding
@@ -197,4 +196,4 @@ def test_from_pyfile_weird_encoding(tmpdir, encoding):
     app = flask.Flask(__name__)
     app.config.from_pyfile(str(f))
     value = app.config["TEST_VALUE"]
-    assert value == u"föö"
+    assert value == "föö"

tests/test_converters.py

@@ -10,7 +10,7 @@ def test_custom_converters(app, client):
             return value.split(",")
 
         def to_url(self, value):
-            base_to_url = super(ListConverter, self).to_url
+            base_to_url = super().to_url
             return ",".join(base_to_url(x) for x in value)
 
     app.url_map.converters["list"] = ListConverter

tests/test_helpers.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.helpers
     ~~~~~~~~~~~~~~~~~~~~~~~
@@ -38,7 +37,7 @@ def has_encoding(name):
         return False
 
 
-class FakePath(object):
+class FakePath:
     """Fake object to represent a ``PathLike object``.
 
     This represents a ``pathlib.Path`` object in python 3.
@@ -73,9 +72,9 @@ class FixedOffset(datetime.tzinfo):
         return datetime.timedelta()
 
 
-class TestJSON(object):
+class TestJSON:
     @pytest.mark.parametrize(
-        "value", (1, "t", True, False, None, [], [1, 2, 3], {}, {"foo": u"🐍"})
+        "value", (1, "t", True, False, None, [], [1, 2, 3], {}, {"foo": "🐍"})
     )
     @pytest.mark.parametrize(
         "encoding",
@@ -126,12 +125,12 @@ class TestJSON(object):
         assert rv.data == b"foo"
 
     @pytest.mark.parametrize(
-        "test_value,expected", [(True, '"\\u2603"'), (False, u'"\u2603"')]
+        "test_value,expected", [(True, '"\\u2603"'), (False, '"\u2603"')]
     )
     def test_json_as_unicode(self, test_value, expected, app, app_ctx):
 
         app.config["JSON_AS_ASCII"] = test_value
-        rv = flask.json.dumps(u"\N{SNOWMAN}")
+        rv = flask.json.dumps("\N{SNOWMAN}")
         assert rv == expected
 
     def test_json_dump_to_file(self, app, app_ctx):
@@ -217,7 +216,7 @@ class TestJSON(object):
         )
 
         for i, d in enumerate(test_dates):
-            url = "/datetest{0}".format(i)
+            url = f"/datetest{i}"
             app.add_url_rule(url, str(i), lambda val=d: flask.jsonify(x=val))
             rv = client.get(url)
             assert rv.mimetype == "application/json"
@@ -262,7 +261,7 @@ class TestJSON(object):
     def test_template_escaping(self, app, req_ctx):
         render = flask.render_template_string
         rv = flask.json.htmlsafe_dumps("</script>")
-        assert rv == u'"\\u003c/script\\u003e"'
+        assert rv == '"\\u003c/script\\u003e"'
         assert type(rv) is str
         rv = render('{{ "</script>"|tojson }}')
         assert rv == '"\\u003c/script\\u003e"'
@@ -280,7 +279,7 @@ class TestJSON(object):
         assert rv == '<a ng-data=\'{"x": ["foo", "bar", "baz\\u0027"]}\'></a>'
 
     def test_json_customization(self, app, client):
-        class X(object):  # noqa: B903, for Python2 compatibility
+        class X:  # noqa: B903, for Python2 compatibility
             def __init__(self, val):
                 self.val = val
 
@@ -315,7 +314,7 @@ class TestJSON(object):
         assert rv.data == b'"<42>"'
 
     def test_blueprint_json_customization(self, app, client):
-        class X(object):  # noqa: B903, for Python2 compatibility
+        class X:  # noqa: B903, for Python2 compatibility
             def __init__(self, val):
                 self.val = val
 
@@ -368,9 +367,9 @@ class TestJSON(object):
         def index():
             return flask.request.args["foo"]
 
-        rv = client.get(u"/?foo=정상처리".encode("euc-kr"))
+        rv = client.get("/?foo=정상처리".encode("euc-kr"))
         assert rv.status_code == 200
-        assert rv.data == u"정상처리".encode("utf-8")
+        assert rv.data == "정상처리".encode()
 
     def test_json_key_sorting(self, app, client):
         app.debug = True
@@ -443,7 +442,7 @@ class TestJSON(object):
             assert lines == sorted_by_str
 
 
-class PyBytesIO(object):
+class PyBytesIO:
     def __init__(self, *args, **kwargs):
         self._io = io.BytesIO(*args, **kwargs)
 
@@ -451,7 +450,7 @@ class PyBytesIO(object):
         return getattr(self._io, name)
 
 
-class TestSendfile(object):
+class TestSendfile:
     def test_send_file_regular(self, app, req_ctx):
         rv = flask.send_file("static/index.html")
         assert rv.direct_passthrough
@@ -516,7 +515,7 @@ class TestSendfile(object):
     @pytest.mark.parametrize(
         "opener",
         [
-            lambda app: io.StringIO(u"Test"),
+            lambda app: io.StringIO("Test"),
             lambda app: open(os.path.join(app.static_folder, "index.html")),
         ],
     )
@@ -673,13 +672,13 @@ class TestSendfile(object):
         (
             ("index.html", "index.html", False),
             (
-                u"Ñandú／pingüino.txt",
+                "Ñandú／pingüino.txt",
                 '"Nandu/pinguino.txt"',
                 "%C3%91and%C3%BA%EF%BC%8Fping%C3%BCino.txt",
             ),
-            (u"Vögel.txt", "Vogel.txt", "V%C3%B6gel.txt"),
+            ("Vögel.txt", "Vogel.txt", "V%C3%B6gel.txt"),
             # ":/" are not safe in filename* value
-            (u"те:/ст", '":/"', "%D1%82%D0%B5%3A%2F%D1%81%D1%82"),
+            ("те:/ст", '":/"', "%D1%82%D0%B5%3A%2F%D1%81%D1%82"),
         ),
     )
     def test_attachment_filename_encoding(self, filename, ascii, utf8):
@@ -775,7 +774,7 @@ class TestSendfile(object):
             flask.send_from_directory("static", "bad\x00")
 
 
-class TestUrlFor(object):
+class TestUrlFor:
     def test_url_for_with_anchor(self, app, req_ctx):
         @app.route("/")
         def index():
@@ -834,7 +833,7 @@ class TestUrlFor(object):
         assert flask.url_for("myview", _method="POST") == "/myview/create"
 
 
-class TestNoImports(object):
+class TestNoImports:
     """Test Flasks are created without import.
 
     Avoiding ``__import__`` helps create Flask instances where there are errors
@@ -853,7 +852,7 @@ class TestNoImports(object):
             AssertionError("Flask(import_name) is importing import_name.")
 
 
-class TestStreaming(object):
+class TestStreaming:
     def test_streaming_with_context(self, app, client):
         @app.route("/")
         def index():
@@ -884,7 +883,7 @@ class TestStreaming(object):
     def test_streaming_with_context_and_custom_close(self, app, client):
         called = []
 
-        class Wrapper(object):
+        class Wrapper:
             def __init__(self, gen):
                 self._gen = gen
 
@@ -927,7 +926,7 @@ class TestStreaming(object):
         assert rv.data == b"flask"
 
 
-class TestSafeJoin(object):
+class TestSafeJoin:
     def test_safe_join(self):
         # Valid combinations of *args and expected joined paths.
         passing = (
@@ -968,7 +967,7 @@ class TestSafeJoin(object):
                 print(flask.safe_join(*args))
 
 
-class TestHelpers(object):
+class TestHelpers:
     @pytest.mark.parametrize(
         "debug, expected_flag, expected_default_flag",
         [

tests/test_instance_config.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.test_instance
     ~~~~~~~~~~~~~~~~~~~

tests/test_json_tag.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 tests.test_json_tag
 ~~~~~~~~~~~~~~~~~~~
@@ -48,7 +47,7 @@ def test_duplicate_tag():
 
 
 def test_custom_tag():
-    class Foo(object):  # noqa: B903, for Python2 compatibility
+    class Foo:  # noqa: B903, for Python2 compatibility
         def __init__(self, data):
             self.data = data
 

tests/test_logging.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 tests.test_logging
 ~~~~~~~~~~~~~~~~~~~

tests/test_regression.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.regression
     ~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -20,7 +19,7 @@ import flask
 _gc_lock = threading.Lock()
 
 
-class assert_no_leak(object):
+class assert_no_leak:
     def __enter__(self):
         gc.disable()
         _gc_lock.acquire()

tests/test_reqctx.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.reqctx
     ~~~~~~~~~~~~
@@ -150,7 +149,7 @@ def test_manual_context_binding(app):
 
 
 @pytest.mark.skipif(greenlet is None, reason="greenlet not installed")
-class TestGreenletContextCopying(object):
+class TestGreenletContextCopying:
     def test_greenlet_context_copying(self, app, client):
         greenlets = []
 
@@ -239,7 +238,7 @@ def test_session_dynamic_cookie_name():
             if flask.request.url.endswith("dynamic_cookie"):
                 return "dynamic_cookie_name"
             else:
-                return super(PathAwareSessionInterface, self).get_cookie_name(app)
+                return super().get_cookie_name(app)
 
     class CustomFlask(flask.Flask):
         session_interface = PathAwareSessionInterface()
@@ -291,7 +290,7 @@ def test_bad_environ_raises_bad_request():
     environ = builder.get_environ()
 
     # use a non-printable character in the Host - this is key to this test
-    environ["HTTP_HOST"] = u"\x8a"
+    environ["HTTP_HOST"] = "\x8a"
 
     with app.request_context(environ):
         response = app.full_dispatch_request()
@@ -311,7 +310,7 @@ def test_environ_for_valid_idna_completes():
     environ = builder.get_environ()
 
     # these characters are all IDNA-compatible
-    environ["HTTP_HOST"] = u"ąśźäüжŠßя.com"
+    environ["HTTP_HOST"] = "ąśźäüжŠßя.com"
 
     with app.request_context(environ):
         response = app.full_dispatch_request()

tests/test_signals.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.signals
     ~~~~~~~~~~~~~~~~~~~~~~~

tests/test_subclassing.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.subclassing
     ~~~~~~~~~~~~~~~~~

tests/test_templating.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.templating
     ~~~~~~~~~~~~~~~~
@@ -417,14 +416,14 @@ def test_template_loader_debugging(test_apps, monkeypatch):
             text = str(record.msg)
             assert '1: trying loader of application "blueprintapp"' in text
             assert (
-                '2: trying loader of blueprint "admin" ' "(blueprintapp.apps.admin)"
+                '2: trying loader of blueprint "admin" (blueprintapp.apps.admin)'
             ) in text
             assert (
-                'trying loader of blueprint "frontend" ' "(blueprintapp.apps.frontend)"
+                'trying loader of blueprint "frontend" (blueprintapp.apps.frontend)'
             ) in text
             assert "Error: the template could not be found" in text
             assert (
-                "looked up from an endpoint that belongs to " 'the blueprint "frontend"'
+                'looked up from an endpoint that belongs to the blueprint "frontend"'
             ) in text
             assert "See https://flask.palletsprojects.com/blueprints/#templates" in text
 

tests/test_testing.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.testing
     ~~~~~~~~~~~~~
@@ -122,8 +121,8 @@ def test_path_is_url(app):
 def test_environbuilder_json_dumps(app):
     """EnvironBuilder.json_dumps() takes settings from the app."""
     app.config["JSON_AS_ASCII"] = False
-    eb = EnvironBuilder(app, json=u"\u20ac")
+    eb = EnvironBuilder(app, json="\u20ac")
-    assert eb.input_stream.read().decode("utf8") == u'"\u20ac"'
+    assert eb.input_stream.read().decode("utf8") == '"\u20ac"'
 
 
 def test_blueprint_with_subdomain():
@@ -324,7 +323,7 @@ def test_client_json_no_app_context(app, client):
     def hello():
         return "Hello, {}!".format(flask.request.json["name"])
 
-    class Namespace(object):
+    class Namespace:
         count = 0
 
         def add(self, app):
@@ -402,7 +401,7 @@ def test_cli_invoke(app):
 
 
 def test_cli_custom_obj(app):
-    class NS(object):
+    class NS:
         called = False
 
     def create_app():

tests/test_user_error_handler.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 tests.test_user_error_handler
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -208,7 +207,7 @@ def test_default_error_handler():
     assert c.get("/slash", follow_redirects=True).data == b"slash"
 
 
-class TestGenericHandlers(object):
+class TestGenericHandlers:
     """Test how very generic handlers are dispatched to."""
 
     class Custom(Exception):

tests/test_views.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     tests.views
     ~~~~~~~~~~~