diff --git a/test/conftest.py b/test/conftest.py
index 8d2850fd..2fe4d8dc 100644
--- a/test/conftest.py
+++ b/test/conftest.py
@@ -11,10 +11,12 @@ import sys
 import tempfile
 import time
 from multiprocessing import Process
+from pathlib import Path
 
 import pytest
-from unit.check.discover_available import discover_available
+
 from unit.check.check_prerequisites import check_prerequisites
+from unit.check.discover_available import discover_available
 from unit.http import HTTP1
 from unit.log import Log
 from unit.log import print_log_on_assert
@@ -265,27 +267,26 @@ def unit_run(state_dir=None):
     if not option.restart and 'unitd' in unit_instance:
         return unit_instance
 
-    builddir   = f'{option.current_dir}/build'
-    libdir     = f'{builddir}/lib'
+    builddir = f'{option.current_dir}/build'
+    libdir = f'{builddir}/lib'
     modulesdir = f'{libdir}/unit/modules'
-    sbindir    = f'{builddir}/sbin'
-    unitd      = f'{sbindir}/unitd'
+    sbindir = f'{builddir}/sbin'
+    unitd = f'{sbindir}/unitd'
 
-    if not os.path.isfile(unitd):
-        exit('Could not find unit')
+    if not Path(unitd).is_file():
+        sys.exit('Could not find unit')
 
-    temp_dir = tempfile.mkdtemp(prefix='unit-test-')
-    option.temp_dir = temp_dir
-    public_dir(temp_dir)
+    temporary_dir = tempfile.mkdtemp(prefix='unit-test-')
+    option.temp_dir = temporary_dir
+    public_dir(temporary_dir)
 
-    if oct(stat.S_IMODE(os.stat(builddir).st_mode)) != '0o777':
+    if oct(stat.S_IMODE(Path(builddir).stat().st_mode)) != '0o777':
         public_dir(builddir)
 
-    statedir = f'{temp_dir}/state' if state_dir is None else state_dir
-    if not os.path.isdir(statedir):
-        os.mkdir(statedir)
+    statedir = f'{temporary_dir}/state' if state_dir is None else state_dir
+    Path(statedir).mkdir(exist_ok=True)
 
-    control_sock = f'{temp_dir}/control.unit.sock'
+    control_sock = f'{temporary_dir}/control.unit.sock'
 
     unitd_args = [
         unitd,
@@ -295,31 +296,32 @@ def unit_run(state_dir=None):
         '--statedir',
         statedir,
         '--pid',
-        f'{temp_dir}/unit.pid',
+        f'{temporary_dir}/unit.pid',
         '--log',
-        f'{temp_dir}/unit.log',
+        f'{temporary_dir}/unit.log',
         '--control',
-        f'unix:{temp_dir}/control.unit.sock',
+        f'unix:{temporary_dir}/control.unit.sock',
         '--tmpdir',
-        temp_dir,
+        temporary_dir,
     ]
 
     if option.user:
         unitd_args.extend(['--user', option.user])
 
-    with open(f'{temp_dir}/unit.log', 'w') as log:
+    with open(f'{temporary_dir}/unit.log', 'w', encoding='utf-8') as log:
         unit_instance['process'] = subprocess.Popen(unitd_args, stderr=log)
 
     if not waitforfiles(control_sock):
         Log.print_log()
-        exit('Could not start unit')
+        sys.exit('Could not start unit')
 
-    unit_instance['temp_dir'] = temp_dir
+    unit_instance['temp_dir'] = temporary_dir
     unit_instance['control_sock'] = control_sock
     unit_instance['unitd'] = unitd
 
-    with open(f'{temp_dir}/unit.pid', 'r') as f:
-        unit_instance['pid'] = f.read().rstrip()
+    unit_instance['pid'] = (
+        Path(f'{temporary_dir}/unit.pid').read_text(encoding='utf-8').rstrip()
+    )
 
     if state_dir is None:
         _clear_conf()
@@ -424,26 +426,27 @@ def _clear_conf(*, log=None):
 
 
 def _clear_temp_dir():
-    temp_dir = unit_instance['temp_dir']
+    temporary_dir = unit_instance['temp_dir']
 
-    if is_findmnt and not waitforunmount(temp_dir, timeout=600):
-        exit('Could not unmount some filesystems in tmpdir ({temp_dir}).')
+    if is_findmnt and not waitforunmount(temporary_dir, timeout=600):
+        sys.exit('Could not unmount filesystems in tmpdir ({temporary_dir}).')
 
-    for item in os.listdir(temp_dir):
-        if item not in [
+    for item in Path(temporary_dir).iterdir():
+        if item.name not in [
             'control.unit.sock',
             'state',
             'unit.pid',
             'unit.log',
         ]:
-            path = os.path.join(temp_dir, item)
-            public_dir(path)
-            if os.path.isfile(path) or stat.S_ISSOCK(os.stat(path).st_mode):
-                os.remove(path)
+
+            public_dir(item)
+
+            if item.is_file() or stat.S_ISSOCK(item.stat().st_mode):
+                item.unlink()
             else:
                 for _ in range(10):
                     try:
-                        shutil.rmtree(path)
+                        shutil.rmtree(item)
                         break
                     except OSError as err:
                         # OSError: [Errno 16] Device or resource busy
@@ -456,7 +459,7 @@ def _clear_temp_dir():
 def _check_processes():
     router_pid = _fds_info['router']['pid']
     controller_pid = _fds_info['controller']['pid']
-    unit_pid = unit_instance['pid']
+    main_pid = unit_instance['pid']
 
     for _ in range(600):
         out = (
@@ -466,7 +469,7 @@ def _check_processes():
             .decode()
             .splitlines()
         )
-        out = [l for l in out if unit_pid in l]
+        out = [l for l in out if main_pid in l]
 
         if len(out) <= 3:
             break
@@ -485,14 +488,14 @@ def _check_processes():
     out = [
         l
         for l in out
-        if re.search(fr'{router_pid}\s+{unit_pid}.*unit: router', l) is None
+        if re.search(fr'{router_pid}\s+{main_pid}.*unit: router', l) is None
     ]
     assert len(out) == 1, 'one router'
 
     out = [
         l
         for l in out
-        if re.search(fr'{controller_pid}\s+{unit_pid}.*unit: controller', l)
+        if re.search(fr'{controller_pid}\s+{main_pid}.*unit: controller', l)
         is None
     ]
     assert len(out) == 0, 'one controller'
@@ -542,9 +545,9 @@ def _check_fds(*, log=None):
 
 
 def _count_fds(pid):
-    procfile = f'/proc/{pid}/fd'
-    if os.path.isdir(procfile):
-        return len(os.listdir(procfile))
+    procfile = Path(f'/proc/{pid}/fd')
+    if procfile.is_dir():
+        return len(list(procfile.iterdir()))
 
     try:
         out = subprocess.check_output(
@@ -616,7 +619,7 @@ def pytest_sessionfinish():
     public_dir(option.cache_dir)
     shutil.rmtree(option.cache_dir)
 
-    if not option.save_log and os.path.isdir(option.temp_dir):
+    if not option.save_log and Path(option.temp_dir).is_dir():
         public_dir(option.temp_dir)
         shutil.rmtree(option.temp_dir)
 
diff --git a/test/python/body_generate/wsgi.py b/test/python/body_generate/wsgi.py
index 73462be6..3d12ac60 100644
--- a/test/python/body_generate/wsgi.py
+++ b/test/python/body_generate/wsgi.py
@@ -1,6 +1,6 @@
 def application(env, start_response):
     length = env.get('HTTP_X_LENGTH', '10')
-    bytes = b'X' * int(length)
+    body = b'X' * int(length)
 
     start_response('200', [('Content-Length', length)])
-    return [bytes]
+    return [body]
diff --git a/test/python/delayed/asgi.py b/test/python/delayed/asgi.py
index 1cb15a92..3c25e49a 100644
--- a/test/python/delayed/asgi.py
+++ b/test/python/delayed/asgi.py
@@ -33,7 +33,9 @@ async def application(scope, receive, send):
         {
             'type': 'http.response.start',
             'status': 200,
-            'headers': [(b'content-length', str(len(body)).encode()),],
+            'headers': [
+                (b'content-length', str(len(body)).encode()),
+            ],
         }
     )
 
diff --git a/test/python/environment/wsgi.py b/test/python/environment/wsgi.py
index 91e0ba49..622b8bc0 100644
--- a/test/python/environment/wsgi.py
+++ b/test/python/environment/wsgi.py
@@ -2,9 +2,11 @@ import os
 
 
 def application(env, start_response):
-    vars = env.get('HTTP_X_VARIABLES').split(',')
+    variables = env.get('HTTP_X_VARIABLES').split(',')
 
-    body = ','.join([str(os.environ[var]) for var in vars if var in os.environ])
+    body = ','.join(
+        [str(os.environ[var]) for var in variables if var in os.environ]
+    )
     body = body.encode()
 
     start_response('200', [('Content-Length', str(len(body)))])
diff --git a/test/python/iter_exception/wsgi.py b/test/python/iter_exception/wsgi.py
index 2779a845..66a09af7 100644
--- a/test/python/iter_exception/wsgi.py
+++ b/test/python/iter_exception/wsgi.py
@@ -8,9 +8,7 @@ class application:
     def __iter__(self):
         self.__i = 0
         self._skip_level = int(self.environ.get('HTTP_X_SKIP', 0))
-        self._not_skip_close = int(
-            self.environ.get('HTTP_X_NOT_SKIP_CLOSE', 0)
-        )
+        self._not_skip_close = int(self.environ.get('HTTP_X_NOT_SKIP_CLOSE', 0))
         self._is_chunked = self.environ.get('HTTP_X_CHUNKED')
 
         headers = [(('Content-Length', '10'))]
diff --git a/test/python/legacy/asgi.py b/test/python/legacy/asgi.py
index 1d45cc4f..8be8932e 100644
--- a/test/python/legacy/asgi.py
+++ b/test/python/legacy/asgi.py
@@ -9,6 +9,8 @@ async def app_http(receive, send):
         {
             'type': 'http.response.start',
             'status': 200,
-            'headers': [(b'content-length', b'0'),],
+            'headers': [
+                (b'content-length', b'0'),
+            ],
         }
     )
diff --git a/test/python/legacy_force/asgi.py b/test/python/legacy_force/asgi.py
index ad2785f2..56c7061d 100644
--- a/test/python/legacy_force/asgi.py
+++ b/test/python/legacy_force/asgi.py
@@ -1,11 +1,10 @@
 def application(scope, receive=None, send=None):
     assert scope['type'] == 'http'
 
-    if receive == None and send == None:
+    if receive is None and send is None:
         return app_http
 
-    else:
-        return app_http(receive, send)
+    return app_http(receive, send)
 
 
 async def app_http(receive, send):
@@ -13,6 +12,8 @@ async def app_http(receive, send):
         {
             'type': 'http.response.start',
             'status': 200,
-            'headers': [(b'content-length', b'0'),],
+            'headers': [
+                (b'content-length', b'0'),
+            ],
         }
     )
diff --git a/test/python/lifespan/empty/asgi.py b/test/python/lifespan/empty/asgi.py
index 27395a28..2071e6e0 100644
--- a/test/python/lifespan/empty/asgi.py
+++ b/test/python/lifespan/empty/asgi.py
@@ -3,7 +3,7 @@ import os
 
 async def handler(prefix, scope, receive, send):
     if scope['type'] == 'lifespan':
-        with open(f'{prefix}version', 'w+') as f:
+        with open(f'{prefix}version', 'w+', encoding='utf-8') as f:
             f.write(
                 f"{scope['asgi']['version']} {scope['asgi']['spec_version']}"
             )
diff --git a/test/python/lifespan/failed/asgi.py b/test/python/lifespan/failed/asgi.py
index 8f315f70..fbd006f9 100644
--- a/test/python/lifespan/failed/asgi.py
+++ b/test/python/lifespan/failed/asgi.py
@@ -6,6 +6,6 @@ async def application(scope, receive, send):
                 await send({"type": "lifespan.startup.failed"})
                 raise Exception('Exception blah')
 
-            elif message['type'] == 'lifespan.shutdown':
+            if message['type'] == 'lifespan.shutdown':
                 await send({'type': 'lifespan.shutdown.complete'})
                 return
diff --git a/test/python/restart/longstart.py b/test/python/restart/longstart.py
index 777398ac..3bc383b7 100644
--- a/test/python/restart/longstart.py
+++ b/test/python/restart/longstart.py
@@ -3,6 +3,7 @@ import time
 
 time.sleep(2)
 
+
 def application(environ, start_response):
     body = str(os.getpid()).encode()
 
diff --git a/test/python/unicode/wsgi.py b/test/python/unicode/wsgi.py
index f2f85f5d..8c9a59dd 100644
--- a/test/python/unicode/wsgi.py
+++ b/test/python/unicode/wsgi.py
@@ -1,7 +1,7 @@
 def application(environ, start_response):
     temp_dir = environ.get('HTTP_TEMP_DIR')
 
-    with open(f'{temp_dir}/tempfile', 'w') as f:
+    with open(f'{temp_dir}/tempfile', 'w', encoding='utf-8') as f:
         f.write('\u26a0\ufe0f')
 
     start_response('200', [('Content-Length', '0')])
diff --git a/test/python/user_group/wsgi.py b/test/python/user_group/wsgi.py
index 4003c064..8f3ba50d 100644
--- a/test/python/user_group/wsgi.py
+++ b/test/python/user_group/wsgi.py
@@ -6,7 +6,12 @@ def application(environ, start_response):
     uid = os.geteuid()
     gid = os.getegid()
 
-    out = json.dumps({'UID': uid, 'GID': gid,}).encode('utf-8')
+    out = json.dumps(
+        {
+            'UID': uid,
+            'GID': gid,
+        }
+    ).encode('utf-8')
 
     start_response(
         '200 OK',
diff --git a/test/test_access_log.py b/test/test_access_log.py
index 3c5e6cbb..873c941a 100644
--- a/test/test_access_log.py
+++ b/test/test_access_log.py
@@ -1,6 +1,7 @@
 import time
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
@@ -17,11 +18,11 @@ def load(script):
     ), 'access_log configure'
 
 
-def set_format(format):
+def set_format(log_format):
     assert 'success' in client.conf(
         {
             'path': f'{option.temp_dir}/access.log',
-            'format': format,
+            'format': log_format,
         },
         'access_log',
     ), 'access_log format'
@@ -283,14 +284,14 @@ def test_access_log_change(temp_dir, wait_for_record):
 def test_access_log_format(wait_for_record):
     load('empty')
 
-    def check_format(format, expect, url='/'):
-        set_format(format)
+    def check_format(log_format, expect, url='/'):
+        set_format(log_format)
 
         assert client.get(url=url)['status'] == 200
         assert wait_for_record(expect, 'access.log') is not None, 'found'
 
-    format = 'BLAH\t0123456789'
-    check_format(format, format)
+    log_format = 'BLAH\t0123456789'
+    check_format(log_format, log_format)
     check_format('$uri $status $uri $status', '/ 200 / 200')
 
 
diff --git a/test/test_asgi_application.py b/test/test_asgi_application.py
index 4b59fafd..e6668b2f 100644
--- a/test/test_asgi_application.py
+++ b/test/test_asgi_application.py
@@ -3,6 +3,7 @@ import time
 
 import pytest
 from packaging import version
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {
diff --git a/test/test_asgi_application_unix_abstract.py b/test/test_asgi_application_unix_abstract.py
index 980a98a9..f35ce0d7 100644
--- a/test/test_asgi_application_unix_abstract.py
+++ b/test/test_asgi_application_unix_abstract.py
@@ -1,4 +1,5 @@
 from packaging import version
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {
diff --git a/test/test_asgi_lifespan.py b/test/test_asgi_lifespan.py
index 5df7475e..e09ea1cc 100644
--- a/test/test_asgi_lifespan.py
+++ b/test/test_asgi_lifespan.py
@@ -1,7 +1,8 @@
-import os
+from pathlib import Path
+
+from packaging import version
 
 from conftest import unit_stop
-from packaging import version
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
@@ -14,32 +15,26 @@ client = ApplicationPython(load_module='asgi')
 
 def assert_cookies(prefix):
     for name in ['startup', 'shutdown']:
-        path = f'{option.test_dir}/python/lifespan/empty/{prefix}{name}'
-        exists = os.path.isfile(path)
-        if exists:
-            os.remove(path)
+        path = Path(f'{option.test_dir}/python/lifespan/empty/{prefix}{name}')
+        exists = path.is_file()
+        path.unlink(missing_ok=True)
 
         assert not exists, name
 
-    path = f'{option.test_dir}/python/lifespan/empty/{prefix}version'
+    path = Path(f'{option.test_dir}/python/lifespan/empty/{prefix}version')
+    versions = path.read_text(encoding='utf-8')
+    path.unlink()
 
-    with open(path, 'r') as f:
-        version = f.read()
-
-    os.remove(path)
-
-    assert version == '3.0 2.0', 'version'
+    assert versions == '3.0 2.0', 'versions'
 
 
 def setup_cookies(prefix):
-    base_dir = f'{option.test_dir}/python/lifespan/empty'
-
-    os.chmod(base_dir, 0o777)
+    base_dir = Path(f'{option.test_dir}/python/lifespan/empty')
+    base_dir.chmod(0o777)
 
     for name in ['startup', 'shutdown', 'version']:
-        path = f'{option.test_dir}/python/lifespan/empty/{prefix}{name}'
-        open(path, 'a').close()
-        os.chmod(path, 0o777)
+        path = Path(f'{option.test_dir}/python/lifespan/empty/{prefix}{name}')
+        path.touch(0o777)
 
 
 def test_asgi_lifespan():
diff --git a/test/test_asgi_targets.py b/test/test_asgi_targets.py
index 63bde713..3d4e2e24 100644
--- a/test/test_asgi_targets.py
+++ b/test/test_asgi_targets.py
@@ -1,5 +1,6 @@
 import pytest
 from packaging import version
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
diff --git a/test/test_asgi_websockets.py b/test/test_asgi_websockets.py
index eb7a20e7..f93c97ab 100644
--- a/test/test_asgi_websockets.py
+++ b/test/test_asgi_websockets.py
@@ -3,6 +3,7 @@ import time
 
 import pytest
 from packaging import version
+
 from unit.applications.lang.python import ApplicationPython
 from unit.applications.websockets import ApplicationWebsocket
 
diff --git a/test/test_client_ip.py b/test/test_client_ip.py
index d7bc399d..538db18b 100644
--- a/test/test_client_ip.py
+++ b/test/test_client_ip.py
@@ -1,4 +1,5 @@
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
diff --git a/test/test_configuration.py b/test/test_configuration.py
index a311922f..a7d519e9 100644
--- a/test/test_configuration.py
+++ b/test/test_configuration.py
@@ -1,6 +1,7 @@
 import socket
 
 import pytest
+
 from unit.control import Control
 
 prerequisites = {'modules': {'python': 'any'}}
diff --git a/test/test_forwarded_header.py b/test/test_forwarded_header.py
index eaa83dce..4b2f9424 100644
--- a/test/test_forwarded_header.py
+++ b/test/test_forwarded_header.py
@@ -1,4 +1,5 @@
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {'modules': {'python': 'any'}}
diff --git a/test/test_go_application.py b/test/test_go_application.py
index 8f406744..469d4346 100644
--- a/test/test_go_application.py
+++ b/test/test_go_application.py
@@ -123,7 +123,7 @@ def test_go_application_command_line_arguments_type():
     client.load('command_line_arguments')
 
     assert 'error' in client.conf(
-        '' "a b c", 'applications/command_line_arguments/arguments'
+        "a b c", 'applications/command_line_arguments/arguments'
     ), 'arguments type'
 
 
diff --git a/test/test_go_isolation.py b/test/test_go_isolation.py
index ba3390ea..a864e9f6 100644
--- a/test/test_go_isolation.py
+++ b/test/test_go_isolation.py
@@ -3,6 +3,7 @@ import os
 import pwd
 
 import pytest
+
 from unit.applications.lang.go import ApplicationGo
 from unit.option import option
 from unit.utils import getns
@@ -319,7 +320,7 @@ def test_go_isolation_rootfs_container_priv(require, temp_dir):
 
 def test_go_isolation_rootfs_automount_tmpfs(is_su, require, temp_dir):
     try:
-        open("/proc/self/mountinfo")
+        open("/proc/self/mountinfo", encoding='utf-8')
     except:
         pytest.skip('The system lacks /proc/self/mountinfo file')
 
diff --git a/test/test_http_header.py b/test/test_http_header.py
index cf5866e9..f6579df5 100644
--- a/test/test_http_header.py
+++ b/test/test_http_header.py
@@ -1,4 +1,5 @@
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {'modules': {'python': 'any'}}
diff --git a/test/test_java_application.py b/test/test_java_application.py
index 3a6a62d6..33151182 100644
--- a/test/test_java_application.py
+++ b/test/test_java_application.py
@@ -1,7 +1,7 @@
 import io
-import os
 import re
 import time
+from pathlib import Path
 
 from unit.applications.lang.java import ApplicationJava
 from unit.option import option
@@ -875,6 +875,7 @@ def test_java_application_get_headers():
     assert headers['X-Reply-0'] == 'blah', 'get headers'
     assert headers['X-Reply-1'] == 'blah', 'get headers 2'
 
+
 def test_java_application_many_headers():
     client.load('get_headers')
 
@@ -956,7 +957,7 @@ def test_java_application_multipart(search_in_file, temp_dir):
 
     reldst = '/uploads'
     fulldst = f'{temp_dir}{reldst}'
-    os.mkdir(fulldst)
+    Path(fulldst).mkdir(parents=True)
     public_dir(fulldst)
 
     fields = {
diff --git a/test/test_java_isolation_rootfs.py b/test/test_java_isolation_rootfs.py
index 66b2a81e..0ed66133 100644
--- a/test/test_java_isolation_rootfs.py
+++ b/test/test_java_isolation_rootfs.py
@@ -2,6 +2,7 @@ import os
 import subprocess
 
 import pytest
+
 from unit.applications.lang.java import ApplicationJava
 from unit.option import option
 
@@ -25,6 +26,7 @@ def setup_method_fixture(temp_dir):
                 f'{temp_dir}/jars',
             ],
             stderr=subprocess.STDOUT,
+            check=True,
         )
 
     except KeyboardInterrupt:
@@ -39,6 +41,7 @@ def setup_method_fixture(temp_dir):
         subprocess.run(
             ["umount", "--lazy", f"{option.temp_dir}/jars"],
             stderr=subprocess.STDOUT,
+            check=True,
         )
 
     except KeyboardInterrupt:
diff --git a/test/test_java_websockets.py b/test/test_java_websockets.py
index c323830b..94ac6f86 100644
--- a/test/test_java_websockets.py
+++ b/test/test_java_websockets.py
@@ -2,6 +2,7 @@ import struct
 import time
 
 import pytest
+
 from unit.applications.lang.java import ApplicationJava
 from unit.applications.websockets import ApplicationWebsocket
 
diff --git a/test/test_njs.py b/test/test_njs.py
index ce92e1ef..aaaa23aa 100644
--- a/test/test_njs.py
+++ b/test/test_njs.py
@@ -1,6 +1,7 @@
-import os
+from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 from unit.option import option
 from unit.utils import waitforfiles
@@ -22,9 +23,9 @@ def setup_method_fixture(temp_dir):
 
 def create_files(*files):
     assets_dir = f'{option.temp_dir}/assets/'
-    os.makedirs(assets_dir)
+    Path(assets_dir).mkdir()
 
-    [open(assets_dir + f, 'a') for f in files]
+    _ = [Path(assets_dir + f).touch() for f in files]
     waitforfiles(*[assets_dir + f for f in files])
 
 
diff --git a/test/test_node_application.py b/test/test_node_application.py
index 5077b9cb..aaad2bcf 100644
--- a/test/test_node_application.py
+++ b/test/test_node_application.py
@@ -1,6 +1,7 @@
 import re
 
 import pytest
+
 from unit.applications.lang.node import ApplicationNode
 from unit.utils import waitforfiles
 
@@ -149,11 +150,13 @@ def test_node_application_write_buffer():
 
     assert client.get()['body'] == 'buffer', 'write buffer'
 
+
 def test_node_application_write_array():
     client.load('write_array')
 
     assert client.get()['body'] == 'array', 'write array'
 
+
 def test_node_application_write_callback(temp_dir):
     client.load('write_callback')
 
@@ -303,11 +306,13 @@ def test_node_application_get_header_names():
         'x-header',
     ], 'get header names'
 
+
 def test_node_application_flush_headers():
     client.load('flush_headers')
 
     assert client.get()['headers']['X-Header'] == 'blah'
 
+
 def test_node_application_has_header():
     client.load('has_header')
 
diff --git a/test/test_node_es_modules.py b/test/test_node_es_modules.py
index ac2c545f..4effafea 100644
--- a/test/test_node_es_modules.py
+++ b/test/test_node_es_modules.py
@@ -1,4 +1,5 @@
 from packaging import version
+
 from unit.applications.lang.node import ApplicationNode
 from unit.applications.websockets import ApplicationWebsocket
 
diff --git a/test/test_node_websockets.py b/test/test_node_websockets.py
index d26452aa..68bdd578 100644
--- a/test/test_node_websockets.py
+++ b/test/test_node_websockets.py
@@ -2,6 +2,7 @@ import struct
 import time
 
 import pytest
+
 from unit.applications.lang.node import ApplicationNode
 from unit.applications.websockets import ApplicationWebsocket
 
diff --git a/test/test_perl_application.py b/test/test_perl_application.py
index 115b0ec7..ad355117 100644
--- a/test/test_perl_application.py
+++ b/test/test_perl_application.py
@@ -1,6 +1,7 @@
 import re
 
 import pytest
+
 from unit.applications.lang.perl import ApplicationPerl
 
 prerequisites = {'modules': {'perl': 'all'}}
diff --git a/test/test_php_application.py b/test/test_php_application.py
index 8a6641cb..90db38fa 100644
--- a/test/test_php_application.py
+++ b/test/test_php_application.py
@@ -7,6 +7,7 @@ import time
 from pathlib import Path
 
 import pytest
+
 from unit.applications.lang.php import ApplicationPHP
 from unit.option import option
 
@@ -93,13 +94,13 @@ def set_opcache(app, val):
 
 
 def set_preload(preload):
-    with open(f'{option.temp_dir}/php.ini', 'w') as ini:
-        ini.write(
-            f"""opcache.preload = {option.test_dir}/php/opcache/preload\
+    Path(f'{option.temp_dir}/php.ini').write_text(
+        f"""opcache.preload = {option.test_dir}/php/opcache/preload\
 /{preload}
 opcache.preload_user = {option.user or getpass.getuser()}
-"""
-        )
+""",
+        encoding='utf-8',
+    )
 
     assert 'success' in client.conf(
         {"file": f"{option.temp_dir}/php.ini"},
@@ -718,9 +719,11 @@ def test_php_application_index_default():
 
 def test_php_application_trailing_slash(temp_dir):
     new_root = f'{temp_dir}/php-root'
-    os.makedirs(f'{new_root}/path')
 
-    Path(f'{new_root}/path/index.php').write_text('<?php echo "OK\n"; ?>')
+    Path(f'{new_root}/path').mkdir(parents=True)
+    Path(f'{new_root}/path/index.php').write_text(
+        '<?php echo "OK\n"; ?>', encoding='utf-8'
+    )
 
     addr = f'{temp_dir}/sock'
 
@@ -761,9 +764,7 @@ def test_php_application_trailing_slash(temp_dir):
 
 
 def test_php_application_forbidden(temp_dir):
-    new_root = f'{temp_dir}/php-root/path'
-    os.makedirs(new_root)
-    os.chmod(new_root, 0o000)
+    Path(f'{temp_dir}/php-root/path').mkdir(mode=0o000, parents=True)
 
     assert 'success' in client.conf(
         {
@@ -787,7 +788,7 @@ def test_php_application_extension_check(temp_dir):
     assert client.get(url='/index.wrong')['status'] != 200, 'status'
 
     new_root = f'{temp_dir}/php'
-    os.mkdir(new_root)
+    Path(new_root).mkdir(parents=True)
     shutil.copy(f'{option.test_dir}/php/phpinfo/index.wrong', new_root)
 
     assert 'success' in client.conf(
diff --git a/test/test_proxy.py b/test/test_proxy.py
index b64e19db..cd16fe5e 100644
--- a/test/test_proxy.py
+++ b/test/test_proxy.py
@@ -3,6 +3,7 @@ import socket
 import time
 
 import pytest
+
 from conftest import run_process
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
diff --git a/test/test_proxy_chunked.py b/test/test_proxy_chunked.py
index f9e9fe10..23476cd9 100644
--- a/test/test_proxy_chunked.py
+++ b/test/test_proxy_chunked.py
@@ -4,6 +4,7 @@ import socket
 import time
 
 import pytest
+
 from conftest import run_process
 from unit.applications.lang.python import ApplicationPython
 from unit.utils import waitforsocket
@@ -52,7 +53,7 @@ def run_server(server_port):
             part = sock.recv(buff_size)
             data += part
 
-            if not len(part):
+            if not part:
                 break
 
         return data
@@ -80,7 +81,7 @@ def run_server(server_port):
                 req = f'{req}{add}\r\n'
 
         for chunk in re.split(r'([@#])', req):
-            if chunk == '@' or chunk == '#':
+            if chunk in ('@', '#'):
                 if chunk == '#':
                     time.sleep(0.1)
                 continue
@@ -90,10 +91,10 @@ def run_server(server_port):
         connection.close()
 
 
-def chunks(chunks):
+def chunks(chunks_lst):
     body = '\r\n\r\n'
 
-    for l, c in chunks:
+    for l, c in chunks_lst:
         body = f'{body}{l}\r\n{c}\r\n'
 
     return f'{body}0\r\n\r\n'
diff --git a/test/test_python_application.py b/test/test_python_application.py
index 058a87df..466a59a2 100644
--- a/test/test_python_application.py
+++ b/test/test_python_application.py
@@ -8,6 +8,7 @@ import venv
 
 import pytest
 from packaging import version
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {'modules': {'python': 'all'}}
@@ -586,8 +587,8 @@ def test_python_application_encoding():
     if not matches:
         pytest.skip('no available locales')
 
-    def unify(str):
-        str.upper().replace('-', '').replace('_', '')
+    def unify(enc):
+        enc.upper().replace('-', '').replace('_', '')
 
     for loc in matches:
         assert 'success' in client.conf(
diff --git a/test/test_python_isolation.py b/test/test_python_isolation.py
index 5b97e292..fd692cb6 100644
--- a/test/test_python_isolation.py
+++ b/test/test_python_isolation.py
@@ -1,9 +1,9 @@
-import os
 import re
 import subprocess
 from pathlib import Path
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 from unit.utils import findmnt
@@ -24,10 +24,10 @@ def get_cgroup(app_name):
 
     cgroup = f'/proc/{pid}/cgroup'
 
-    if not os.path.isfile(cgroup):
+    if not Path(cgroup).is_file():
         pytest.skip(f'no cgroup at {cgroup}')
 
-    with open(cgroup, 'r') as f:
+    with open(cgroup, 'r', encoding='utf-8') as f:
         return f.read().rstrip()
 
 
diff --git a/test/test_python_procman.py b/test/test_python_procman.py
index 4643a9b8..b4378c4f 100644
--- a/test/test_python_procman.py
+++ b/test/test_python_procman.py
@@ -4,6 +4,7 @@ import subprocess
 import time
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
diff --git a/test/test_reconfigure.py b/test/test_reconfigure.py
index a5fe1b1a..28d1b4c9 100644
--- a/test/test_reconfigure.py
+++ b/test/test_reconfigure.py
@@ -1,6 +1,7 @@
 import time
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
diff --git a/test/test_reconfigure_tls.py b/test/test_reconfigure_tls.py
index 50638391..3cd01b13 100644
--- a/test/test_reconfigure_tls.py
+++ b/test/test_reconfigure_tls.py
@@ -3,6 +3,7 @@ import ssl
 import time
 
 import pytest
+
 from unit.applications.tls import ApplicationTLS
 
 prerequisites = {'modules': {'openssl': 'any'}}
@@ -93,6 +94,8 @@ def test_reconfigure_tls_2():
 
     clear_conf()
 
+    success = False
+
     try:
         ssl_sock.do_handshake()
     except ssl.SSLError:
diff --git a/test/test_respawn.py b/test/test_respawn.py
index dc465cda..03254037 100644
--- a/test/test_respawn.py
+++ b/test/test_respawn.py
@@ -3,6 +3,7 @@ import subprocess
 import time
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {'modules': {'python': 'any'}}
diff --git a/test/test_response_headers.py b/test/test_response_headers.py
index ec07c8c4..e62c1293 100644
--- a/test/test_response_headers.py
+++ b/test/test_response_headers.py
@@ -1,8 +1,9 @@
 from pathlib import Path
 
 import pytest
-from unit.applications.proto import ApplicationProto
+
 from unit.applications.lang.python import ApplicationPython
+from unit.applications.proto import ApplicationProto
 from unit.option import option
 
 client = ApplicationProto()
@@ -12,7 +13,7 @@ client_python = ApplicationPython()
 @pytest.fixture(autouse=True)
 def setup_method_fixture(temp_dir):
     path = Path(f'{temp_dir}/index.html')
-    path.write_text('0123456789')
+    path.write_text('0123456789', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
diff --git a/test/test_return.py b/test/test_return.py
index 3ffcaa4e..af15b886 100644
--- a/test/test_return.py
+++ b/test/test_return.py
@@ -1,6 +1,7 @@
 import re
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -90,7 +91,7 @@ def test_return_update():
 def test_return_location():
     reserved = ":/?#[]@!&'()*+,;="
     unreserved = (
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" "0123456789-._~"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
     )
     unsafe = " \"%<>\\^`{|}"
     unsafe_enc = "%20%22%25%3C%3E%5C%5E%60%7B%7C%7D"
diff --git a/test/test_rewrite.py b/test/test_rewrite.py
index 0a4ffe42..f94fb528 100644
--- a/test/test_rewrite.py
+++ b/test/test_rewrite.py
@@ -1,6 +1,7 @@
-import os
+from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -39,9 +40,9 @@ def set_rewrite(rewrite, uri):
 
 def test_rewrite(findall, wait_for_record):
     assert client.get()['status'] == 200
-    assert wait_for_record(rf'\[notice\].*"routes/1" selected') is not None
-    assert len(findall(rf'\[notice\].*URI rewritten to "/new"')) == 1
-    assert len(findall(rf'\[notice\].*URI rewritten')) == 1
+    assert wait_for_record(r'\[notice\].*"routes/1" selected') is not None
+    assert len(findall(r'\[notice\].*URI rewritten to "/new"')) == 1
+    assert len(findall(r'\[notice\].*URI rewritten')) == 1
 
     set_rewrite("", "")
     assert client.get()['status'] == 200
@@ -131,11 +132,9 @@ def test_rewrite_location():
 
 
 def test_rewrite_share(temp_dir):
-    os.makedirs(f'{temp_dir}/dir')
-    os.makedirs(f'{temp_dir}/foo')
-
-    with open(f'{temp_dir}/foo/index.html', 'w') as fooindex:
-        fooindex.write('fooindex')
+    Path(f'{temp_dir}/dir').mkdir()
+    Path(f'{temp_dir}/foo/').mkdir()
+    Path(f'{temp_dir}/foo/index.html').write_text('fooindex', encoding='utf-8')
 
     # same action block
 
diff --git a/test/test_routing.py b/test/test_routing.py
index ce5952eb..0b6eced2 100644
--- a/test/test_routing.py
+++ b/test/test_routing.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
@@ -24,8 +25,8 @@ def setup_method_fixture():
     ), 'routing configure'
 
 
-def route(route):
-    return client.conf([route], 'routes')
+def route(conf_route):
+    return client.conf([conf_route], 'routes')
 
 
 def route_match(match):
@@ -40,19 +41,21 @@ def route_match_invalid(match):
     ), 'route match configure invalid'
 
 
-def host(host, status):
+def host(host_header, status):
     assert (
-        client.get(headers={'Host': host, 'Connection': 'close'})['status']
+        client.get(headers={'Host': host_header, 'Connection': 'close'})[
+            'status'
+        ]
         == status
     ), 'match host'
 
 
-def cookie(cookie, status):
+def cookie(cookie_header, status):
     assert (
         client.get(
             headers={
                 'Host': 'localhost',
-                'Cookie': cookie,
+                'Cookie': cookie_header,
                 'Connection': 'close',
             },
         )['status']
diff --git a/test/test_ruby_application.py b/test/test_ruby_application.py
index 3ac62f71..aae89999 100644
--- a/test/test_ruby_application.py
+++ b/test/test_ruby_application.py
@@ -2,6 +2,7 @@ import re
 import subprocess
 
 import pytest
+
 from unit.applications.lang.ruby import ApplicationRuby
 
 prerequisites = {'modules': {'ruby': 'all'}}
diff --git a/test/test_settings.py b/test/test_settings.py
index 0cdc6c0d..9d37d6ca 100644
--- a/test/test_settings.py
+++ b/test/test_settings.py
@@ -4,6 +4,7 @@ import subprocess
 import time
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 
 prerequisites = {'modules': {'python': 'any'}}
diff --git a/test/test_static.py b/test/test_static.py
index 98f27c7f..e2fc2283 100644
--- a/test/test_static.py
+++ b/test/test_static.py
@@ -1,7 +1,9 @@
 import os
 import socket
+from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 from unit.utils import waitforfiles
 
@@ -11,18 +13,13 @@ client = ApplicationProto()
 
 @pytest.fixture(autouse=True)
 def setup_method_fixture(temp_dir):
-    os.makedirs(f'{temp_dir}/assets/dir')
     assets_dir = f'{temp_dir}/assets'
 
-    with open(f'{assets_dir}/index.html', 'w') as index, open(
-        f'{assets_dir}/README', 'w'
-    ) as readme, open(f'{assets_dir}/log.log', 'w') as log, open(
-        f'{assets_dir}/dir/file', 'w'
-    ) as file:
-        index.write('0123456789')
-        readme.write('readme')
-        log.write('[debug]')
-        file.write('blah')
+    Path(f'{assets_dir}/dir').mkdir(parents=True)
+    Path(f'{assets_dir}/index.html').write_text('0123456789', encoding='utf-8')
+    Path(f'{assets_dir}/README').write_text('readme', encoding='utf-8')
+    Path(f'{assets_dir}/log.log').write_text('[debug]', encoding='utf-8')
+    Path(f'{assets_dir}/dir/file').write_text('blah', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
@@ -103,7 +100,7 @@ def test_static_etag(temp_dir):
     assert etag != etag_2, 'different ETag'
     assert etag == client.get(url='/')['headers']['ETag'], 'same ETag'
 
-    with open(f'{temp_dir}/assets/index.html', 'w') as f:
+    with open(f'{temp_dir}/assets/index.html', 'w', encoding='utf-8') as f:
         f.write('blah')
 
     assert etag != client.get(url='/')['headers']['ETag'], 'new ETag'
@@ -119,18 +116,16 @@ def test_static_redirect():
 def test_static_space_in_name(temp_dir):
     assets_dir = f'{temp_dir}/assets'
 
-    os.rename(
-        f'{assets_dir}/dir/file',
-        f'{assets_dir}/dir/fi le',
-    )
+    Path(f'{assets_dir}/dir/file').rename(f'{assets_dir}/dir/fi le')
+
     assert waitforfiles(f'{assets_dir}/dir/fi le')
     assert client.get(url='/dir/fi le')['body'] == 'blah', 'file name'
 
-    os.rename(f'{assets_dir}/dir', f'{assets_dir}/di r')
+    Path(f'{assets_dir}/dir').rename(f'{assets_dir}/di r')
     assert waitforfiles(f'{assets_dir}/di r/fi le')
     assert client.get(url='/di r/fi le')['body'] == 'blah', 'dir name'
 
-    os.rename(f'{assets_dir}/di r', f'{assets_dir}/ di r ')
+    Path(f'{assets_dir}/di r').rename(f'{assets_dir}/ di r ')
     assert waitforfiles(f'{assets_dir}/ di r /fi le')
     assert (
         client.get(url='/ di r /fi le')['body'] == 'blah'
@@ -149,17 +144,14 @@ def test_static_space_in_name(temp_dir):
         == 'blah'
     ), 'encoded 2'
 
-    os.rename(
-        f'{assets_dir}/ di r /fi le',
-        f'{assets_dir}/ di r / fi le ',
-    )
+    Path(f'{assets_dir}/ di r /fi le').rename(f'{assets_dir}/ di r / fi le ')
     assert waitforfiles(f'{assets_dir}/ di r / fi le ')
     assert (
         client.get(url='/%20di%20r%20/%20fi%20le%20')['body'] == 'blah'
     ), 'file name enclosing'
 
     try:
-        open(f'{temp_dir}/ф а', 'a').close()
+        Path(f'{temp_dir}/ф а').touch()
         utf8 = True
 
     except KeyboardInterrupt:
@@ -169,17 +161,13 @@ def test_static_space_in_name(temp_dir):
         utf8 = False
 
     if utf8:
-        os.rename(
-            f'{assets_dir}/ di r / fi le ',
-            f'{assets_dir}/ di r /фа йл',
+        Path(f'{assets_dir}/ di r / fi le ').rename(
+            f'{assets_dir}/ di r /фа йл'
         )
         assert waitforfiles(f'{assets_dir}/ di r /фа йл')
         assert client.get(url='/ di r /фа йл')['body'] == 'blah'
 
-        os.rename(
-            f'{assets_dir}/ di r ',
-            f'{assets_dir}/ди ректория',
-        )
+        Path(f'{assets_dir}/ di r ').rename(f'{assets_dir}/ди ректория')
         assert waitforfiles(f'{assets_dir}/ди ректория/фа йл')
         assert (
             client.get(url='/ди ректория/фа йл')['body'] == 'blah'
diff --git a/test/test_static_chroot.py b/test/test_static_chroot.py
index fb14d7ab..31e10b4e 100644
--- a/test/test_static_chroot.py
+++ b/test/test_static_chroot.py
@@ -2,21 +2,23 @@ import os
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 from unit.option import option
 
 prerequisites = {'features': {'chroot': True}}
 
 client = ApplicationProto()
+test_path = f'/{os.path.relpath(Path(__file__))}'
 
 
 @pytest.fixture(autouse=True)
 def setup_method_fixture(temp_dir):
-    os.makedirs(f'{temp_dir}/assets/dir')
-    Path(f'{temp_dir}/assets/index.html').write_text('0123456789')
-    Path(f'{temp_dir}/assets/dir/file').write_text('blah')
-
-    client.test_path = f'/{os.path.relpath(Path(__file__))}'
+    Path(f'{temp_dir}/assets/dir').mkdir(parents=True)
+    Path(f'{temp_dir}/assets/index.html').write_text(
+        '0123456789', encoding='utf-8'
+    )
+    Path(f'{temp_dir}/assets/dir/file').write_text('blah', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
@@ -85,7 +87,7 @@ def test_static_chroot_empty():
     assert client.get(url='/dir/file')['status'] == 200, 'empty absolute'
 
     assert 'success' in update_action("", ".$uri")
-    assert client.get(url=client.test_path)['status'] == 200, 'empty relative'
+    assert client.get(url=test_path)['status'] == 200, 'empty relative'
 
 
 def test_static_chroot_relative(require):
@@ -95,10 +97,10 @@ def test_static_chroot_relative(require):
     assert client.get(url='/dir/file')['status'] == 403, 'relative chroot'
 
     assert 'success' in client.conf({"share": ".$uri"}, 'routes/0/action')
-    assert client.get(url=client.test_path)['status'] == 200, 'relative share'
+    assert client.get(url=test_path)['status'] == 200, 'relative share'
 
     assert 'success' in update_action(".", ".$uri")
-    assert client.get(url=client.test_path)['status'] == 200, 'relative'
+    assert client.get(url=test_path)['status'] == 200, 'relative'
 
 
 def test_static_chroot_variables(temp_dir):
diff --git a/test/test_static_fallback.py b/test/test_static_fallback.py
index 25e466a3..9b5fcb53 100644
--- a/test/test_static_fallback.py
+++ b/test/test_static_fallback.py
@@ -2,6 +2,7 @@ import os
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -11,7 +12,7 @@ client = ApplicationProto()
 def setup_method_fixture(temp_dir):
     assets_dir = f'{temp_dir}/assets'
     os.makedirs(f'{assets_dir}/dir')
-    Path(f'{assets_dir}/index.html').write_text('0123456789')
+    Path(f'{assets_dir}/index.html').write_text('0123456789', encoding='utf-8')
 
     os.makedirs(f'{assets_dir}/403')
     os.chmod(f'{assets_dir}/403', 0o000)
diff --git a/test/test_static_mount.py b/test/test_static_mount.py
index d8d3b698..41b436e2 100644
--- a/test/test_static_mount.py
+++ b/test/test_static_mount.py
@@ -3,6 +3,7 @@ import subprocess
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 prerequisites = {'features': {'chroot': True}, 'privileged_user': True}
@@ -15,9 +16,11 @@ def setup_method_fixture(temp_dir):
     os.makedirs(f'{temp_dir}/assets/dir/mount')
     os.makedirs(f'{temp_dir}/assets/dir/dir')
     os.makedirs(f'{temp_dir}/assets/mount')
-    Path(f'{temp_dir}/assets/index.html').write_text('index')
-    Path(f'{temp_dir}/assets/dir/dir/file').write_text('file')
-    Path(f'{temp_dir}/assets/mount/index.html').write_text('mount')
+    Path(f'{temp_dir}/assets/index.html').write_text('index', encoding='utf-8')
+    Path(f'{temp_dir}/assets/dir/dir/file').write_text('file', encoding='utf-8')
+    Path(f'{temp_dir}/assets/mount/index.html').write_text(
+        'mount', encoding='utf-8'
+    )
 
     try:
         subprocess.check_output(
diff --git a/test/test_static_share.py b/test/test_static_share.py
index fa16d267..ee53fe9b 100644
--- a/test/test_static_share.py
+++ b/test/test_static_share.py
@@ -2,6 +2,7 @@ import os
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -12,8 +13,8 @@ def setup_method_fixture(temp_dir):
     os.makedirs(f'{temp_dir}/assets/dir')
     os.makedirs(f'{temp_dir}/assets/dir2')
 
-    Path(f'{temp_dir}/assets/dir/file').write_text('1')
-    Path(f'{temp_dir}/assets/dir2/file2').write_text('2')
+    Path(f'{temp_dir}/assets/dir/file').write_text('1', encoding='utf-8')
+    Path(f'{temp_dir}/assets/dir2/file2').write_text('2', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
diff --git a/test/test_static_symlink.py b/test/test_static_symlink.py
index 3b04d70c..2d402d48 100644
--- a/test/test_static_symlink.py
+++ b/test/test_static_symlink.py
@@ -2,6 +2,7 @@ import os
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 prerequisites = {'features': {'chroot': True}}
@@ -12,8 +13,10 @@ client = ApplicationProto()
 @pytest.fixture(autouse=True)
 def setup_method_fixture(temp_dir):
     os.makedirs(f'{temp_dir}/assets/dir/dir')
-    Path(f'{temp_dir}/assets/index.html').write_text('0123456789')
-    Path(f'{temp_dir}/assets/dir/file').write_text('blah')
+    Path(f'{temp_dir}/assets/index.html').write_text(
+        '0123456789', encoding='utf-8'
+    )
+    Path(f'{temp_dir}/assets/dir/file').write_text('blah', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
diff --git a/test/test_static_types.py b/test/test_static_types.py
index a468319a..e931d949 100644
--- a/test/test_static_types.py
+++ b/test/test_static_types.py
@@ -1,6 +1,7 @@
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -10,9 +11,9 @@ client = ApplicationProto()
 def setup_method_fixture(temp_dir):
     Path(f'{temp_dir}/assets').mkdir()
     for ext in ['.xml', '.mp4', '.php', '', '.txt', '.html', '.png']:
-        Path(f'{temp_dir}/assets/file{ext}').write_text(ext)
+        Path(f'{temp_dir}/assets/file{ext}').write_text(ext, encoding='utf-8')
 
-    Path(f'{temp_dir}/assets/index.html').write_text('index')
+    Path(f'{temp_dir}/assets/index.html').write_text('index', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
diff --git a/test/test_static_variables.py b/test/test_static_variables.py
index 5afd0127..62753750 100644
--- a/test/test_static_variables.py
+++ b/test/test_static_variables.py
@@ -2,6 +2,7 @@ import os
 from pathlib import Path
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 client = ApplicationProto()
@@ -11,9 +12,11 @@ client = ApplicationProto()
 def setup_method_fixture(temp_dir):
     os.makedirs(f'{temp_dir}/assets/dir')
     os.makedirs(f'{temp_dir}/assets/d$r')
-    Path(f'{temp_dir}/assets/index.html').write_text('0123456789')
-    Path(f'{temp_dir}/assets/dir/file').write_text('file')
-    Path(f'{temp_dir}/assets/d$r/file').write_text('d$r')
+    Path(f'{temp_dir}/assets/index.html').write_text(
+        '0123456789', encoding='utf-8'
+    )
+    Path(f'{temp_dir}/assets/dir/file').write_text('file', encoding='utf-8')
+    Path(f'{temp_dir}/assets/d$r/file').write_text('d$r', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
diff --git a/test/test_tls.py b/test/test_tls.py
index a56d5428..09921773 100644
--- a/test/test_tls.py
+++ b/test/test_tls.py
@@ -2,8 +2,10 @@ import io
 import ssl
 import subprocess
 import time
+from pathlib import Path
 
 import pytest
+
 from unit.applications.tls import ApplicationTLS
 from unit.option import option
 
@@ -53,9 +55,8 @@ def context_cert_req(cert='root'):
 
 
 def generate_ca_conf():
-    with open(f'{option.temp_dir}/ca.conf', 'w') as f:
-        f.write(
-            f"""[ ca ]
+    Path(f'{option.temp_dir}/ca.conf').write_text(
+        f"""[ ca ]
 default_ca = myca
 
 [ myca ]
@@ -72,17 +73,13 @@ copy_extensions = copy
 commonName = optional
 
 [ myca_extensions ]
-basicConstraints = critical,CA:TRUE"""
-        )
+basicConstraints = critical,CA:TRUE""",
+        encoding='utf-8',
+    )
 
-    with open(f'{option.temp_dir}/certserial', 'w') as f:
-        f.write('1000')
-
-    with open(f'{option.temp_dir}/certindex', 'w') as f:
-        f.write('')
-
-    with open(f'{option.temp_dir}/certindex.attr', 'w') as f:
-        f.write('')
+    Path(f'{option.temp_dir}/certserial').write_text('1000', encoding='utf-8')
+    Path(f'{option.temp_dir}/certindex').touch()
+    Path(f'{option.temp_dir}/certindex.attr').touch()
 
 
 def remove_tls(application='empty', port=8080):
@@ -322,8 +319,8 @@ def test_tls_certificate_chain(temp_dir):
 
     with open(crt_path, 'wb') as crt, open(end_path, 'rb') as end, open(
         int_path, 'rb'
-    ) as int:
-        crt.write(end.read() + int.read())
+    ) as inter:
+        crt.write(end.read() + inter.read())
 
     # incomplete chain
 
@@ -428,7 +425,9 @@ def test_tls_certificate_chain_long(temp_dir):
             else f'{temp_dir}/int{i}.crt'
         )
 
-        with open(f'{temp_dir}/all.crt', 'a') as chain, open(path) as cert:
+        with open(f'{temp_dir}/all.crt', 'a', encoding='utf-8') as chain, open(
+            path, encoding='utf-8'
+        ) as cert:
             chain.write(cert.read())
 
     assert 'success' in client.certificate_load(
diff --git a/test/test_tls_conf_command.py b/test/test_tls_conf_command.py
index 4d772c83..5a9a3f32 100644
--- a/test/test_tls_conf_command.py
+++ b/test/test_tls_conf_command.py
@@ -1,6 +1,7 @@
 import ssl
 
 import pytest
+
 from unit.applications.tls import ApplicationTLS
 
 prerequisites = {'modules': {'openssl': 'any'}}
diff --git a/test/test_tls_sni.py b/test/test_tls_sni.py
index aa7ed3c5..61d72125 100644
--- a/test/test_tls_sni.py
+++ b/test/test_tls_sni.py
@@ -2,6 +2,7 @@ import ssl
 import subprocess
 
 import pytest
+
 from unit.applications.tls import ApplicationTLS
 from unit.option import option
 
@@ -104,7 +105,7 @@ def config_bundles(bundles):
 
 
 def generate_ca_conf():
-    with open(f'{option.temp_dir}/ca.conf', 'w') as f:
+    with open(f'{option.temp_dir}/ca.conf', 'w', encoding='utf-8') as f:
         f.write(
             f"""[ ca ]
 default_ca = myca
@@ -126,10 +127,10 @@ commonName = optional
 basicConstraints = critical,CA:TRUE"""
         )
 
-    with open(f'{option.temp_dir}/certserial', 'w') as f:
+    with open(f'{option.temp_dir}/certserial', 'w', encoding='utf-8') as f:
         f.write('1000')
 
-    with open(f'{option.temp_dir}/certindex', 'w') as f:
+    with open(f'{option.temp_dir}/certindex', 'w', encoding='utf-8') as f:
         f.write('')
 
 
diff --git a/test/test_upstreams_rr.py b/test/test_upstreams_rr.py
index ecf24add..a2dc5c68 100644
--- a/test/test_upstreams_rr.py
+++ b/test/test_upstreams_rr.py
@@ -2,6 +2,7 @@ import os
 import re
 
 import pytest
+
 from unit.applications.lang.python import ApplicationPython
 from unit.option import option
 
diff --git a/test/test_usr1.py b/test/test_usr1.py
index ce756fc0..ecb4d8fd 100644
--- a/test/test_usr1.py
+++ b/test/test_usr1.py
@@ -1,5 +1,6 @@
 import os
 import signal
+from pathlib import Path
 
 from unit.applications.lang.python import ApplicationPython
 from unit.log import Log
@@ -23,14 +24,14 @@ def test_usr1_access_log(search_in_file, temp_dir, unit_pid, wait_for_record):
 
     assert waitforfiles(log_path), 'open'
 
-    os.rename(log_path, f'{temp_dir}/{log_new}')
+    Path(log_path).rename(f'{temp_dir}/{log_new}')
 
     assert client.get()['status'] == 200
 
     assert (
         wait_for_record(r'"GET / HTTP/1.1" 200 0 "-" "-"', log_new) is not None
     ), 'rename new'
-    assert not os.path.isfile(log_path), 'rename old'
+    assert not Path(log_path).is_file(), 'rename old'
 
     os.kill(unit_pid, signal.SIGUSR1)
 
@@ -51,7 +52,7 @@ def test_usr1_unit_log(search_in_file, temp_dir, unit_pid, wait_for_record):
     log_path = f'{temp_dir}/unit.log'
     log_path_new = f'{temp_dir}/{log_new}'
 
-    os.rename(log_path, log_path_new)
+    Path(log_path).rename(log_path_new)
 
     Log.swap(log_new)
 
@@ -60,7 +61,7 @@ def test_usr1_unit_log(search_in_file, temp_dir, unit_pid, wait_for_record):
         assert client.post(body=body)['status'] == 200
 
         assert wait_for_record(body, log_new) is not None, 'rename new'
-        assert not os.path.isfile(log_path), 'rename old'
+        assert not Path(log_path).is_file(), 'rename old'
 
         os.kill(unit_pid, signal.SIGUSR1)
 
@@ -75,13 +76,10 @@ def test_usr1_unit_log(search_in_file, temp_dir, unit_pid, wait_for_record):
     finally:
         # merge two log files into unit.log to check alerts
 
-        with open(log_path, 'r', errors='ignore') as unit_log:
-            log = unit_log.read()
-
-        with open(log_path, 'w') as unit_log, open(
-            log_path_new, 'r', errors='ignore'
-        ) as unit_log_new:
-            unit_log.write(unit_log_new.read())
-            unit_log.write(log)
+        path_log = Path(log_path)
+        log = path_log.read_text(encoding='utf-8', errors='ignore') + Path(
+            log_path_new
+        ).read_text(encoding='utf-8', errors='ignore')
+        path_log.write_text(log, encoding='utf-8', errors='ignore')
 
         Log.swap(log_new)
diff --git a/test/test_variables.py b/test/test_variables.py
index 0b7b9ea8..9aab8a62 100644
--- a/test/test_variables.py
+++ b/test/test_variables.py
@@ -1,11 +1,11 @@
-import os
-from pathlib import Path
 import re
 import time
+from pathlib import Path
 
 import pytest
-from unit.applications.proto import ApplicationProto
+
 from unit.applications.lang.python import ApplicationPython
+from unit.applications.proto import ApplicationProto
 from unit.option import option
 
 client = ApplicationProto()
@@ -22,11 +22,11 @@ def setup_method_fixture():
     ), 'configure routes'
 
 
-def set_format(format):
+def set_format(log_format):
     assert 'success' in client.conf(
         {
             'path': f'{option.temp_dir}/access.log',
-            'format': format,
+            'format': log_format,
         },
         'access_log',
     ), 'access_log format'
@@ -127,8 +127,8 @@ def test_variables_uri(search_in_file, wait_for_record):
 
 
 def test_variables_uri_no_cache(temp_dir):
-    os.makedirs(f'{temp_dir}/foo/bar')
-    Path(f'{temp_dir}/foo/bar/index.html').write_text('index')
+    Path(f'{temp_dir}/foo/bar').mkdir(parents=True)
+    Path(f'{temp_dir}/foo/bar/index.html').write_text('index', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
@@ -443,7 +443,7 @@ def test_variables_response_header(temp_dir, wait_for_record):
     # share
 
     Path(f'{temp_dir}/foo').mkdir()
-    Path(f'{temp_dir}/foo/index.html').write_text('index')
+    Path(f'{temp_dir}/foo/index.html').write_text('index', encoding='utf-8')
 
     assert 'success' in client.conf(
         {
@@ -514,11 +514,11 @@ def test_variables_response_header_application(require, wait_for_record):
 
 
 def test_variables_invalid(temp_dir):
-    def check_variables(format):
+    def check_variables(log_format):
         assert 'error' in client.conf(
             {
                 'path': f'{temp_dir}/access.log',
-                'format': format,
+                'format': log_format,
             },
             'access_log',
         ), 'access_log format'
diff --git a/test/unit/applications/lang/go.py b/test/unit/applications/lang/go.py
index 5aca5048..2479d4f6 100644
--- a/test/unit/applications/lang/go.py
+++ b/test/unit/applications/lang/go.py
@@ -53,7 +53,7 @@ class ApplicationGo(ApplicationProto):
 
         replace_path = f'{option.current_dir}/build/go/src/unit.nginx.org/go'
 
-        with open(f'{temp_dir}go.mod', 'w') as f:
+        with open(f'{temp_dir}go.mod', 'w', encoding='utf-8') as f:
             f.write(
                 f"""module test/app
 require unit.nginx.org/go v0.0.0
diff --git a/test/unit/applications/lang/php.py b/test/unit/applications/lang/php.py
index 2ab172b0..ac59ec1b 100644
--- a/test/unit/applications/lang/php.py
+++ b/test/unit/applications/lang/php.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import shutil
 
 from unit.applications.proto import ApplicationProto
@@ -15,10 +15,9 @@ class ApplicationPHP(ApplicationProto):
         if kwargs.get('isolation') and kwargs['isolation'].get('rootfs'):
             rootfs = kwargs['isolation']['rootfs']
 
-            if not os.path.exists(f'{rootfs}/app/php/'):
-                os.makedirs(f'{rootfs}/app/php/')
+            Path(f'{rootfs}/app/php/').mkdir(parents=True, exist_ok=True)
 
-            if not os.path.exists(f'{rootfs}/app/php/{script}'):
+            if not Path(f'{rootfs}/app/php/{script}').exists():
                 shutil.copytree(script_path, f'{rootfs}/app/php/{script}')
 
             script_path = f'/app/php/{script}'
diff --git a/test/unit/applications/lang/python.py b/test/unit/applications/lang/python.py
index 67304d12..67684b04 100644
--- a/test/unit/applications/lang/python.py
+++ b/test/unit/applications/lang/python.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import shutil
 from urllib.parse import quote
 
@@ -26,10 +26,9 @@ class ApplicationPython(ApplicationProto):
         if kwargs.get('isolation') and kwargs['isolation'].get('rootfs'):
             rootfs = kwargs['isolation']['rootfs']
 
-            if not os.path.exists(f'{rootfs}/app/python/'):
-                os.makedirs(f'{rootfs}/app/python/')
+            Path(f'{rootfs}/app/python/').mkdir(parents=True, exist_ok=True)
 
-            if not os.path.exists(f'{rootfs}/app/python/{name}'):
+            if not Path(f'{rootfs}/app/python/{name}').exists():
                 shutil.copytree(script_path, f'{rootfs}/app/python/{name}')
 
             script_path = f'/app/python/{name}'
diff --git a/test/unit/applications/tls.py b/test/unit/applications/tls.py
index 50a27348..75354dd9 100644
--- a/test/unit/applications/tls.py
+++ b/test/unit/applications/tls.py
@@ -79,7 +79,7 @@ subjectAltName = @alt_names
 
 {a_names}'''
 
-        with open(conf_path, 'w') as f:
+        with open(conf_path, 'w', encoding='utf-8') as f:
             f.write(
                 f'''[ req ]
 default_bits = 2048
diff --git a/test/unit/applications/websockets.py b/test/unit/applications/websockets.py
index 29725943..a8e563d0 100644
--- a/test/unit/applications/websockets.py
+++ b/test/unit/applications/websockets.py
@@ -6,6 +6,7 @@ import select
 import struct
 
 import pytest
+
 from unit.applications.proto import ApplicationProto
 
 GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
@@ -69,7 +70,7 @@ class ApplicationWebsocket(ApplicationProto):
         return struct.pack('!H', code) + reason.encode('utf-8')
 
     def frame_read(self, sock, read_timeout=60):
-        def recv_bytes(sock, bytes):
+        def recv_bytes(sock, bytes_len):
             data = b''
             while True:
                 rlist = select.select([sock], [], [], read_timeout)[0]
@@ -80,9 +81,9 @@ class ApplicationWebsocket(ApplicationProto):
                         pytest.fail("Can't read response from server.")
                     break
 
-                data += sock.recv(bytes - len(data))
+                data += sock.recv(bytes_len - len(data))
 
-                if len(data) == bytes:
+                if len(data) == bytes_len:
                     break
 
             return data
@@ -206,18 +207,18 @@ class ApplicationWebsocket(ApplicationProto):
                     end = frame_len
                 pos = end
 
-    def message(self, sock, type, message, fragmention_size=None, **kwargs):
+    def message(self, sock, mes_type, message, fragmention_size=None, **kwargs):
         message_len = len(message)
 
         if fragmention_size is None:
             fragmention_size = message_len
 
         if message_len <= fragmention_size:
-            self.frame_write(sock, type, message, **kwargs)
+            self.frame_write(sock, mes_type, message, **kwargs)
             return
 
         pos = 0
-        op_code = type
+        op_code = mes_type
         while pos < message_len:
             end = min(pos + fragmention_size, message_len)
             fin = end == message_len
diff --git a/test/unit/check/check_prerequisites.py b/test/unit/check/check_prerequisites.py
index 44c3f10f..ea319346 100644
--- a/test/unit/check/check_prerequisites.py
+++ b/test/unit/check/check_prerequisites.py
@@ -1,4 +1,5 @@
 import pytest
+
 from unit.option import option
 
 
diff --git a/test/unit/check/isolation.py b/test/unit/check/isolation.py
index e31179e8..861c0818 100644
--- a/test/unit/check/isolation.py
+++ b/test/unit/check/isolation.py
@@ -1,5 +1,5 @@
 import json
-import os
+from pathlib import Path
 
 from unit.applications.lang.go import ApplicationGo
 from unit.applications.lang.java import ApplicationJava
@@ -145,11 +145,12 @@ def check_isolation():
 
     isolation = {'user': userns}
 
-    unp_clone_path = '/proc/sys/kernel/unprivileged_userns_clone'
-    if os.path.exists(unp_clone_path):
-        with open(unp_clone_path, 'r') as f:
-            if str(f.read()).rstrip() == '1':
-                isolation['unprivileged_userns_clone'] = True
+    path_clone = Path('/proc/sys/kernel/unprivileged_userns_clone')
+    if (
+        path_clone.exists()
+        and path_clone.read_text(encoding='utf-8').rstrip() == '1'
+    ):
+        isolation['unprivileged_userns_clone'] = True
 
     for ns in allns:
         ns_value = getns(ns)
diff --git a/test/unit/check/node.py b/test/unit/check/node.py
index 6a3d581f..b206e914 100644
--- a/test/unit/check/node.py
+++ b/test/unit/check/node.py
@@ -1,11 +1,11 @@
-import os
 import subprocess
+from pathlib import Path
 
 from unit.option import option
 
 
 def check_node():
-    if not os.path.exists(f'{option.current_dir}/node/node_modules'):
+    if not Path(f'{option.current_dir}/node/node_modules').exists():
         return False
 
     try:
diff --git a/test/unit/control.py b/test/unit/control.py
index 164d0e60..8cdf1887 100644
--- a/test/unit/control.py
+++ b/test/unit/control.py
@@ -16,7 +16,7 @@ def args_handler(conf_func):
         elif argcount == 3:
             conf = args[0]
 
-            if isinstance(conf, dict) or isinstance(conf, list):
+            if isinstance(conf, (dict, list)):
                 conf = json.dumps(conf)
 
             url = args[1] if len(args) == 2 else url_default
diff --git a/test/unit/http.py b/test/unit/http.py
index 5a6a1a1b..9401501b 100644
--- a/test/unit/http.py
+++ b/test/unit/http.py
@@ -7,6 +7,7 @@ import select
 import socket
 
 import pytest
+
 from unit.option import option
 
 
@@ -38,10 +39,7 @@ class HTTP1:
         if 'sock' not in kwargs:
             sock = socket.socket(sock_types[sock_type], socket.SOCK_STREAM)
 
-            if (
-                sock_type == sock_types['ipv4']
-                or sock_type == sock_types['ipv6']
-            ):
+            if sock_type in (sock_types['ipv4'], sock_types['ipv6']):
                 sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
 
             if 'wrapper' in kwargs:
@@ -202,7 +200,7 @@ class HTTP1:
 
             data += part
 
-            if not len(part):
+            if not part:
                 break
 
         return data
@@ -263,7 +261,7 @@ class HTTP1:
                 size = int(chunks.pop(0), 16)
 
             except ValueError:
-                pytest.fail(f'Invalid chunk size {size}')
+                pytest.fail('Invalid chunk size')
 
             if size == 0:
                 assert len(chunks) == 1, 'last zero size'
diff --git a/test/unit/status.py b/test/unit/status.py
index 84c958a3..95096a96 100644
--- a/test/unit/status.py
+++ b/test/unit/status.py
@@ -30,16 +30,16 @@ class Status:
                     for k in d1
                     if k in d2
                 }
-            else:
-                return d1 - d2
+
+            return d1 - d2
 
         return find_diffs(Status.control.conf_get('/status'), Status._status)
 
     def get(path='/'):
-        path = path.split('/')[1:]
+        path_lst = path.split('/')[1:]
         diff = Status.diff()
 
-        for p in path:
-            diff = diff[p]
+        for part in path_lst:
+            diff = diff[part]
 
         return diff