diff --git a/asyncssh/agent.py b/asyncssh/agent.py
index 74b69b5..acdad35 100644
--- a/asyncssh/agent.py
+++ b/asyncssh/agent.py
@@ -252,7 +252,7 @@ async def _make_request(self, msgtype: int, *args: bytes) -> \
 
                 resplen = int.from_bytes((await reader.readexactly(4)), 'big')
 
-                resp = SSHPacket((await reader.readexactly(resplen)))
+                resp = SSHPacket(await reader.readexactly(resplen))
                 resptype = resp.get_byte()
 
                 return resptype, resp
diff --git a/asyncssh/auth.py b/asyncssh/auth.py
index 377b255..2457689 100644
--- a/asyncssh/auth.py
+++ b/asyncssh/auth.py
@@ -181,7 +181,7 @@ async def _start(self) -> None:
 
             self._gss = self._conn.get_gss_context()
             self._gss.reset()
-            mechs = b''.join((String(mech) for mech in self._gss.mechs))
+            mechs = b''.join(String(mech) for mech in self._gss.mechs)
             await self.send_request(UInt32(len(self._gss.mechs)), mechs)
         else:
             self._conn.try_next_auth()
diff --git a/asyncssh/connection.py b/asyncssh/connection.py
index df25aef..d6cb52d 100644
--- a/asyncssh/connection.py
+++ b/asyncssh/connection.py
@@ -725,7 +725,7 @@ def get_port(self) -> int:
         if hasattr(self._server, 'get_port'):
             return self._server.get_port()
         else:
-            ports = set(addr[1] for addr in self.get_addresses())
+            ports = {addr[1] for addr in self.get_addresses()}
             return ports.pop() if len(ports) == 1 else 0
 
     def close(self) -> None:
diff --git a/asyncssh/crypto/x509.py b/asyncssh/crypto/x509.py
index cded74f..14f91ae 100644
--- a/asyncssh/crypto/x509.py
+++ b/asyncssh/crypto/x509.py
@@ -94,8 +94,8 @@ def _to_purpose_oids(purposes: _Purposes) -> _PurposeOIDs:
     if not purposes or 'any' in purposes or _purpose_any in purposes:
         purpose_oids = None
     else:
-        purpose_oids = set(_purpose_to_oid.get(p) or x509.ObjectIdentifier(p)
-                           for p in purposes)
+        purpose_oids = {_purpose_to_oid.get(p) or x509.ObjectIdentifier(p)
+                           for p in purposes}
 
     return purpose_oids
 
@@ -143,8 +143,8 @@ class X509Name(x509.Name):
         ('CN', x509.NameOID.COMMON_NAME),
         ('DC', x509.NameOID.DOMAIN_COMPONENT))
 
-    _to_oid = dict((k, v) for k, v in _attrs)
-    _from_oid = dict((v, k) for k, v in _attrs)
+    _to_oid = dict(_attrs)
+    _from_oid = {v: k for k, v in _attrs}
 
     def __init__(self, name: _NameInit):
         if isinstance(name, str):
diff --git a/asyncssh/known_hosts.py b/asyncssh/known_hosts.py
index d80ac60..9ab6a09 100644
--- a/asyncssh/known_hosts.py
+++ b/asyncssh/known_hosts.py
@@ -208,8 +208,8 @@ def _match(self, host: str, addr: str,
                 ip = None
 
         if port:
-            host = '[{}]:{}'.format(host, port) if host else ''
-            addr = '[{}]:{}'.format(addr, port) if addr else ''
+            host = f'[{host}]:{port}' if host else ''
+            addr = f'[{addr}]:{port}' if addr else ''
 
         matches = []
         matches += self._exact_entries.get(host, [])
diff --git a/asyncssh/public_key.py b/asyncssh/public_key.py
index fd1c412..b3d7138 100644
--- a/asyncssh/public_key.py
+++ b/asyncssh/public_key.py
@@ -1941,8 +1941,8 @@ def validate_chain(self, trust_chain: Sequence['SSHX509Certificate'],
                        host_principal: str = '') -> None:
         """Validate an X.509 certificate chain"""
 
-        trust_store = set(c for c in trust_chain if c.subject != c.issuer) | \
-            set(c for c in trusted_certs)
+        trust_store = {c for c in trust_chain if c.subject != c.issuer} | \
+            set(trusted_certs)
 
         if trusted_cert_paths:
             self._expand_trust_store(self, trusted_cert_paths, trust_store)
diff --git a/asyncssh/sftp.py b/asyncssh/sftp.py
index 71cce08..6d29767 100644
--- a/asyncssh/sftp.py
+++ b/asyncssh/sftp.py
@@ -1628,7 +1628,7 @@ def _format(self, k: str, v: object) -> Optional[str]:
             return _file_types.get(cast(int, v), str(v)) \
                 if v != FILEXFER_TYPE_UNKNOWN else None
         elif k == 'permissions':
-            return '{:04o}'.format(cast(int, v))
+            return f'{cast(int, v):04o}'
         elif k in ('atime', 'crtime', 'mtime', 'ctime'):
             return self._format_ns(k)
         elif k in ('atime_ns', 'crtime_ns', 'mtime_ns', 'ctime_ns'):
diff --git a/examples/simple_keyed_server.py b/examples/simple_keyed_server.py
index 0da91ab..754d5f3 100755
--- a/examples/simple_keyed_server.py
+++ b/examples/simple_keyed_server.py
@@ -42,7 +42,7 @@ def connection_made(self, conn: asyncssh.SSHServerConnection) -> None:
     def begin_auth(self, username: str) -> bool:
         try:
             self._conn.set_authorized_keys('authorized_keys/%s' % username)
-        except IOError:
+        except OSError:
             pass
 
         return True
diff --git a/tests/test_channel.py b/tests/test_channel.py
index e535679..201704d 100644
--- a/tests/test_channel.py
+++ b/tests/test_channel.py
@@ -271,7 +271,7 @@ async def _begin_session(self, stdin, stdout, stderr):
         elif action == 'agent':
             try:
                 async with asyncssh.connect_agent(self._conn) as agent:
-                    stdout.write(str(len((await agent.get_keys()))) + '\n')
+                    stdout.write(str(len(await agent.get_keys())) + '\n')
             except (OSError, asyncssh.ChannelOpenError):
                 stdout.channel.exit(1)
         elif action == 'agent_sock':
@@ -280,7 +280,7 @@ async def _begin_session(self, stdin, stdout, stderr):
             if agent_path:
                 async with asyncssh.connect_agent(agent_path) as agent:
                     await asyncio.sleep(0.1)
-                    stdout.write(str(len((await agent.get_keys()))) + '\n')
+                    stdout.write(str(len(await agent.get_keys())) + '\n')
             else:
                 stdout.channel.exit(1)
         elif action == 'rejected_agent':
@@ -428,11 +428,11 @@ async def _begin_session(self, stdin, stdout, stderr):
         elif action == 'empty_data':
             stdin.channel.send_packet(MSG_CHANNEL_DATA, String(''))
         elif action == 'partial_unicode':
-            data = '\xff\xff'.encode('utf-8')
+            data = '\xff\xff'.encode()
             stdin.channel.send_packet(MSG_CHANNEL_DATA, String(data[:3]))
             stdin.channel.send_packet(MSG_CHANNEL_DATA, String(data[3:]))
         elif action == 'partial_unicode_at_eof':
-            data = '\xff\xff'.encode('utf-8')
+            data = '\xff\xff'.encode()
             stdin.channel.send_packet(MSG_CHANNEL_DATA, String(data[:3]))
         elif action == 'unicode_error':
             stdin.channel.send_packet(MSG_CHANNEL_DATA, String(b'\xff'))
@@ -767,7 +767,7 @@ async def test_unknown_channel_request(self):
             async with self.connect() as conn:
                 chan, _ = await _create_session(conn)
 
-                self.assertFalse((await chan.make_request('unknown')))
+                self.assertFalse(await chan.make_request('unknown'))
 
     @asynctest
     async def test_invalid_channel_request(self):
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 1afc6bd..9eadf45 100644
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -798,7 +798,7 @@ async def test_import_known_hosts(self):
 
         known_hosts_path = os.path.join('.ssh', 'known_hosts')
 
-        with open(known_hosts_path, 'r') as f:
+        with open(known_hosts_path) as f:
             known_hosts = asyncssh.import_known_hosts(f.read())
 
         async with self.connect(known_hosts=known_hosts):
diff --git a/tests/test_process.py b/tests/test_process.py
index 32f11c1..b0c5e5a 100644
--- a/tests/test_process.py
+++ b/tests/test_process.py
@@ -460,7 +460,7 @@ async def test_ignoring_invalid_unicode(self):
     async def test_incomplete_unicode(self):
         """Test incomplete Unicode data"""
 
-        data = '\u2000'.encode('utf-8')[:2]
+        data = '\u2000'.encode()[:2]
 
         with open('stdin', 'wb') as file:
             file.write(data)
@@ -586,7 +586,7 @@ async def test_stdin_open_file(self):
         with open('stdin', 'w') as file:
             file.write(data)
 
-        file = open('stdin', 'r')
+        file = open('stdin')
 
         async with self.connect() as conn:
             result = await conn.run('echo', stdin=file)
@@ -773,7 +773,7 @@ async def test_stdout_file(self):
         async with self.connect() as conn:
             result = await conn.run('echo', input=data, stdout='stdout')
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, data)
@@ -806,7 +806,7 @@ async def test_stdout_pathlib(self):
         async with self.connect() as conn:
             result = await conn.run('echo', input=data, stdout=Path('stdout'))
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, data)
@@ -824,7 +824,7 @@ async def test_stdout_open_file(self):
         async with self.connect() as conn:
             result = await conn.run('echo', input=data, stdout=file)
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, data)
@@ -842,7 +842,7 @@ async def test_stdout_open_file_keep_open(self):
                 await conn.run('echo', input=data, stdout=file, recv_eof=False)
                 await conn.run('echo', input=data, stdout=file, recv_eof=False)
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, 2*data)
@@ -995,7 +995,7 @@ async def test_change_stdout(self):
 
             result = await process.wait()
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, 'xxx')
@@ -1246,7 +1246,7 @@ async def test_stdout_aiofile(self):
         async with self.connect() as conn:
             result = await conn.run('echo', input=data, stdout=file)
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, data)
@@ -1264,7 +1264,7 @@ async def test_stdout_aiofile_keep_open(self):
                 await conn.run('echo', input=data, stdout=file, recv_eof=False)
                 await conn.run('echo', input=data, stdout=file, recv_eof=False)
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             stdout_data = file.read()
 
         self.assertEqual(stdout_data, 2*data)
@@ -1316,7 +1316,7 @@ async def test_pause_async_file_writer(self):
                 await conn.run('delay', input=data, stdout=file,
                                stderr=asyncssh.DEVNULL)
 
-        with open('stdout', 'r') as file:
+        with open('stdout') as file:
             self.assertEqual(file.read(), data)
 
 
diff --git a/tests/test_public_key.py b/tests/test_public_key.py
index 70dbf73..ddb50ba 100644
--- a/tests/test_public_key.py
+++ b/tests/test_public_key.py
@@ -180,7 +180,7 @@ def select_passphrase(cipher, pbe_version=0):
                                          'rc4-40', 'rc4-128'):
         return 'passphrase'.encode('utf-16-be')
     else:
-        return 'passphrase'.encode('utf-8')
+        return b'passphrase'
 
 
 class _TestPublicKey(TempDirTestCase):
diff --git a/tests/test_sftp.py b/tests/test_sftp.py
index fc3ef30..13068d5 100644
--- a/tests/test_sftp.py
+++ b/tests/test_sftp.py
@@ -1182,7 +1182,7 @@ async def test_glob(self, sftp):
 
             for pattern, matches in glob_tests:
                 with self.subTest(pattern=pattern):
-                    self.assertEqual(sorted((await sftp.glob(pattern))),
+                    self.assertEqual(sorted(await sftp.glob(pattern)),
                                      matches)
 
             self.assertEqual((await sftp.glob([b'fil*1', 'fil*dir'])),
@@ -1264,29 +1264,29 @@ async def test_stat(self, sftp):
                 with self.assertRaises(SFTPNoSuchFile):
                     await sftp.stat('badlink')
 
-            self.assertTrue((await sftp.isdir('dir')))
-            self.assertFalse((await sftp.isdir('file')))
+            self.assertTrue(await sftp.isdir('dir'))
+            self.assertFalse(await sftp.isdir('file'))
 
             if self._symlink_supported: # pragma: no branch
-                self.assertFalse((await sftp.isdir('badlink')))
-                self.assertTrue((await sftp.isdir('dirlink')))
-                self.assertFalse((await sftp.isdir('filelink')))
+                self.assertFalse(await sftp.isdir('badlink'))
+                self.assertTrue(await sftp.isdir('dirlink'))
+                self.assertFalse(await sftp.isdir('filelink'))
 
-            self.assertFalse((await sftp.isfile('dir')))
-            self.assertTrue((await sftp.isfile('file')))
+            self.assertFalse(await sftp.isfile('dir'))
+            self.assertTrue(await sftp.isfile('file'))
 
             if self._symlink_supported: # pragma: no branch
-                self.assertFalse((await sftp.isfile('badlink')))
-                self.assertFalse((await sftp.isfile('dirlink')))
-                self.assertTrue((await sftp.isfile('filelink')))
+                self.assertFalse(await sftp.isfile('badlink'))
+                self.assertFalse(await sftp.isfile('dirlink'))
+                self.assertTrue(await sftp.isfile('filelink'))
 
-            self.assertFalse((await sftp.islink('dir')))
-            self.assertFalse((await sftp.islink('file')))
+            self.assertFalse(await sftp.islink('dir'))
+            self.assertFalse(await sftp.islink('file'))
 
             if self._symlink_supported: # pragma: no branch
-                self.assertTrue((await sftp.islink('badlink')))
-                self.assertTrue((await sftp.islink('dirlink')))
-                self.assertTrue((await sftp.islink('filelink')))
+                self.assertTrue(await sftp.islink('badlink'))
+                self.assertTrue(await sftp.islink('dirlink'))
+                self.assertTrue(await sftp.islink('filelink'))
         finally:
             remove('dir file badlink dirlink filelink')
 
@@ -1605,8 +1605,8 @@ async def test_utime_v4(self, sftp):
             self.assertEqual(stat_result.st_mtime_ns, 2250000000)
             self.assertEqual((await sftp.getatime('file')), 1.0)
             self.assertEqual((await sftp.getatime_ns('file')), 1000000000)
-            self.assertIsNotNone((await sftp.getcrtime('file')))
-            self.assertIsNotNone((await sftp.getcrtime_ns('file')))
+            self.assertIsNotNone(await sftp.getcrtime('file'))
+            self.assertIsNotNone(await sftp.getcrtime_ns('file'))
             self.assertEqual((await sftp.getmtime('file')), 2.25)
             self.assertEqual((await sftp.getmtime_ns('file')), 2250000000)
 
@@ -1619,8 +1619,8 @@ async def test_utime_v4(self, sftp):
             self.assertEqual(stat_result.st_mtime_ns, 4750000000)
             self.assertEqual((await sftp.getatime('file')), 3.5)
             self.assertEqual((await sftp.getatime_ns('file')), 3500000000)
-            self.assertIsNotNone((await sftp.getcrtime('file')))
-            self.assertIsNotNone((await sftp.getcrtime_ns('file')))
+            self.assertIsNotNone(await sftp.getcrtime('file'))
+            self.assertIsNotNone(await sftp.getcrtime_ns('file'))
             self.assertEqual((await sftp.getmtime('file')), 4.75)
             self.assertEqual((await sftp.getmtime_ns('file')), 4750000000)
         finally:
@@ -1633,8 +1633,8 @@ async def test_exists(self, sftp):
         try:
             self._create_file('file1')
 
-            self.assertTrue((await sftp.exists('file1')))
-            self.assertFalse((await sftp.exists('file2')))
+            self.assertTrue(await sftp.exists('file1'))
+            self.assertFalse(await sftp.exists('file2'))
         finally:
             remove('file1')
 
@@ -1648,8 +1648,8 @@ async def test_lexists(self, sftp):
         try:
             os.symlink('file', 'link1')
 
-            self.assertTrue((await sftp.lexists('link1')))
-            self.assertFalse((await sftp.lexists('link2')))
+            self.assertTrue(await sftp.lexists('link1'))
+            self.assertFalse(await sftp.lexists('link2'))
         finally:
             remove('link1')
 
@@ -1769,7 +1769,7 @@ async def test_listdir(self, sftp):
             os.mkdir('dir')
             self._create_file('dir/file1')
             self._create_file('dir/file2')
-            self.assertEqual(sorted((await sftp.listdir('dir'))),
+            self.assertEqual(sorted(await sftp.listdir('dir')),
                              ['.', '..', 'file1', 'file2'])
         finally:
             remove('dir')
@@ -1782,7 +1782,7 @@ async def test_listdir_v4(self, sftp):
             os.mkdir('dir')
             self._create_file('dir/file1')
             self._create_file('dir/file2')
-            self.assertEqual(sorted((await sftp.listdir('dir'))),
+            self.assertEqual(sorted(await sftp.listdir('dir')),
                              ['.', '..', 'file1', 'file2'])
         finally:
             remove('dir')
@@ -2204,7 +2204,7 @@ async def test_open_read_parallel(self, sftp):
             self._create_file('file', 40*1024*'\0')
 
             f = await sftp.open('file')
-            self.assertEqual(len((await f.read(64*1024))), 40*1024)
+            self.assertEqual(len(await f.read(64*1024)), 40*1024)
         finally:
             if f: # pragma: no branch
                 await f.close()
@@ -2978,8 +2978,8 @@ async def test_file_utime_v4(self, sftp):
             self.assertEqual(stat_result.st_mtime_ns, 2250000000)
             self.assertEqual((await sftp.getatime('file')), 1.0)
             self.assertEqual((await sftp.getatime_ns('file')), 1000000000)
-            self.assertIsNotNone((await sftp.getcrtime('file')))
-            self.assertIsNotNone((await sftp.getcrtime_ns('file')))
+            self.assertIsNotNone(await sftp.getcrtime('file'))
+            self.assertIsNotNone(await sftp.getcrtime_ns('file'))
             self.assertEqual((await sftp.getmtime('file')), 2.25)
             self.assertEqual((await sftp.getmtime_ns('file')), 2250000000)
 
@@ -2992,8 +2992,8 @@ async def test_file_utime_v4(self, sftp):
             self.assertEqual(stat_result.st_mtime_ns, 4750000000)
             self.assertEqual((await sftp.getatime('file')), 3.5)
             self.assertEqual((await sftp.getatime_ns('file')), 3500000000)
-            self.assertIsNotNone((await sftp.getcrtime('file')))
-            self.assertIsNotNone((await sftp.getcrtime_ns('file')))
+            self.assertIsNotNone(await sftp.getcrtime('file'))
+            self.assertIsNotNone(await sftp.getcrtime_ns('file'))
             self.assertEqual((await sftp.getmtime('file')), 4.75)
             self.assertEqual((await sftp.getmtime_ns('file')), 4750000000)
         finally:
@@ -3073,7 +3073,7 @@ async def test_file_sync(self, sftp):
 
         try:
             f = await sftp.open('file', 'w')
-            self.assertIsNone((await f.fsync()))
+            self.assertIsNone(await f.fsync())
         finally:
             if f: # pragma: no branch
                 await f.close()
@@ -3598,7 +3598,7 @@ async def _short_ok_response(self, pkttype, pktid, packet):
 
         with patch('asyncssh.sftp.SFTPServerHandler._process_packet',
                    _short_ok_response):
-            self.assertIsNone((await sftp.mkdir('dir')))
+            self.assertIsNone(await sftp.mkdir('dir'))
 
     @sftp_test
     async def test_malformed_realpath_response(self, sftp):
@@ -4078,7 +4078,7 @@ async def test_chroot_glob(self, sftp):
         try:
             self._create_file('chroot/file1')
             self._create_file('chroot/file2')
-            self.assertEqual(sorted((await sftp.glob('/file*'))),
+            self.assertEqual(sorted(await sftp.glob('/file*')),
                              ['/file1', '/file2'])
         finally:
             remove('chroot/file1 chroot/file2')
@@ -4515,7 +4515,7 @@ async def start_server(cls):
     async def test_large_listdir(self, sftp):
         """Test large listdir result"""
 
-        self.assertEqual(len((await sftp.readdir('/'))), 100000)
+        self.assertEqual(len(await sftp.readdir('/')), 100000)
 
 
 @unittest.skipIf(sys.platform == 'win32', 'skip statvfs tests on Windows')
@@ -4551,7 +4551,7 @@ def _check_statvfs(self, sftp_statvfs):
     async def test_statvfs(self, sftp):
         """Test getting attributes on a filesystem"""
 
-        self._check_statvfs((await sftp.statvfs('.')))
+        self._check_statvfs(await sftp.statvfs('.'))
 
     @sftp_test
     async def test_file_statvfs(self, sftp):
@@ -4563,7 +4563,7 @@ async def test_file_statvfs(self, sftp):
             self._create_file('file')
 
             f = await sftp.open('file')
-            self._check_statvfs((await f.statvfs()))
+            self._check_statvfs(await f.statvfs())
         finally:
             if f: # pragma: no branch
                 await f.close()
@@ -5280,7 +5280,7 @@ async def test_source_bytes(self):
         """Test passing a byte string to SCP"""
 
         with self.assertRaises(OSError):
-            await scp('\xff:xxx'.encode('utf-8'), '.')
+            await scp('\xff:xxx'.encode(), '.')
 
     @asynctest
     async def test_source_open_connection(self):
diff --git a/tests/test_stream.py b/tests/test_stream.py
index 63dfbc6..e4a5915 100644
--- a/tests/test_stream.py
+++ b/tests/test_stream.py
@@ -49,7 +49,7 @@ async def _begin_session(self, stdin, stdout, stderr):
             await stdin.read(1)
             stdout.write('\n')
         elif action == 'disconnect':
-            stdout.write((await stdin.read(1)))
+            stdout.write(await stdin.read(1))
             raise asyncssh.ConnectionLost('Connection lost')
         elif action == 'custom_disconnect':
             await stdin.read(1)
diff --git a/tests/test_x509.py b/tests/test_x509.py
index 7ae1e55..d923dd6 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -79,7 +79,7 @@ def test_generate(self):
 
         cert = self.generate_certificate(purposes='secureShellClient')
 
-        self.assertEqual(cert.purposes, set((_purpose_secureShellClient,)))
+        self.assertEqual(cert.purposes, {_purpose_secureShellClient})
 
     def test_generate_ca(self):
         """Test X.509 CA certificate generation"""
diff --git a/tests/util.py b/tests/util.py
index 2c016e8..0c364d8 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -216,7 +216,7 @@ def make_certificate(cert_version, cert_type, key, signing_key, principals,
     """Construct an SSH certificate"""
 
     keydata = key.encode_ssh_public()
-    principals = b''.join((String(p) for p in principals))
+    principals = b''.join(String(p) for p in principals)
     options = _encode_options(options) if options else b''
     extensions = _encode_options(extensions) if extensions else b''
     signing_keydata = b''.join((String(signing_key.algorithm),