diff --git a/psutil/tests/test_bsd.py b/psutil/tests/test_bsd.py
index 72cfb068a..c836dfd5c 100755
--- a/psutil/tests/test_bsd.py
+++ b/psutil/tests/test_bsd.py
@@ -130,8 +130,8 @@ def test_cpu_count_logical(self):
 
     @pytest.mark.skipif(not which('sysctl'), reason="sysctl cmd not available")
     @pytest.mark.skipif(
-        NETBSD, reason="skipped on NETBSD"
-    )  # we check /proc/meminfo
+        NETBSD, reason="skipped on NETBSD"  # we check /proc/meminfo
+    )
     def test_virtual_memory_total(self):
         num = sysctl('hw.physmem')
         assert num == psutil.virtual_memory().total
diff --git a/psutil/tests/test_contracts.py b/psutil/tests/test_contracts.py
index b0aefa0e2..2f58cd172 100755
--- a/psutil/tests/test_contracts.py
+++ b/psutil/tests/test_contracts.py
@@ -275,7 +275,7 @@ def test_net_if_addrs(self):
                 assert isinstance(addr.netmask, (str, type(None)))
                 assert isinstance(addr.broadcast, (str, type(None)))
 
-    @pytest.mark.skipif(QEMU_USER, reason='QEMU user not supported')
+    @pytest.mark.skipif(QEMU_USER, reason="QEMU user not supported")
     def test_net_if_stats(self):
         # Duplicate of test_system.py. Keep it anyway.
         for ifname, info in psutil.net_if_stats().items():
@@ -288,7 +288,7 @@ def test_net_if_stats(self):
             assert isinstance(info.speed, int)
             assert isinstance(info.mtu, int)
 
-    @pytest.mark.skipif(not HAS_NET_IO_COUNTERS, reason='not supported')
+    @pytest.mark.skipif(not HAS_NET_IO_COUNTERS, reason="not supported")
     def test_net_io_counters(self):
         # Duplicate of test_system.py. Keep it anyway.
         for ifname in psutil.net_io_counters(pernic=True):
diff --git a/psutil/tests/test_memleaks.py b/psutil/tests/test_memleaks.py
index 32c69b3e7..697baf0b5 100755
--- a/psutil/tests/test_memleaks.py
+++ b/psutil/tests/test_memleaks.py
@@ -405,7 +405,7 @@ def test_disk_partitions(self):
 
     @pytest.mark.skipif(
         LINUX and not os.path.exists('/proc/diskstats'),
-        reason='/proc/diskstats not available on this Linux version',
+        reason="/proc/diskstats not available on this Linux version",
     )
     @fewtimes_if_linux()
     def test_disk_io_counters(self):
@@ -420,7 +420,7 @@ def test_pids(self):
     # --- net
 
     @fewtimes_if_linux()
-    @pytest.mark.skipif(not HAS_NET_IO_COUNTERS, reason='not supported')
+    @pytest.mark.skipif(not HAS_NET_IO_COUNTERS, reason="not supported")
     def test_net_io_counters(self):
         self.execute(lambda: psutil.net_io_counters(nowrap=False))
 
diff --git a/psutil/tests/test_misc.py b/psutil/tests/test_misc.py
index eaa965fd9..3a4275c80 100755
--- a/psutil/tests/test_misc.py
+++ b/psutil/tests/test_misc.py
@@ -991,7 +991,7 @@ def test_pstree(self):
     def test_netstat(self):
         self.assert_stdout('netstat.py')
 
-    @pytest.mark.skipif(QEMU_USER, reason='QEMU user not supported')
+    @pytest.mark.skipif(QEMU_USER, reason="QEMU user not supported")
     def test_ifconfig(self):
         self.assert_stdout('ifconfig.py')
 
diff --git a/psutil/tests/test_process.py b/psutil/tests/test_process.py
index 4132b4168..a0e5199ec 100755
--- a/psutil/tests/test_process.py
+++ b/psutil/tests/test_process.py
@@ -579,7 +579,7 @@ def test_threads(self):
 
     @retry_on_failure()
     @skip_on_access_denied(only_if=MACOS)
-    @pytest.mark.skipif(not HAS_THREADS, reason='not supported')
+    @pytest.mark.skipif(not HAS_THREADS, reason="not supported")
     def test_threads_2(self):
         p = self.spawn_psproc()
         if OPENBSD:
@@ -991,7 +991,7 @@ def test_cwd_2(self):
         p = self.spawn_psproc(cmd)
         call_until(lambda: p.cwd() == os.path.dirname(os.getcwd()))
 
-    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason='not supported')
+    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason="not supported")
     def test_cpu_affinity(self):
         p = psutil.Process()
         initial = p.cpu_affinity()
@@ -1030,7 +1030,7 @@ def test_cpu_affinity(self):
         p.cpu_affinity(set(all_cpus))
         p.cpu_affinity(tuple(all_cpus))
 
-    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason='not supported')
+    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason="not supported")
     def test_cpu_affinity_errs(self):
         p = self.spawn_psproc()
         invalid_cpu = [len(psutil.cpu_times(percpu=True)) + 10]
@@ -1043,7 +1043,7 @@ def test_cpu_affinity_errs(self):
         with pytest.raises(ValueError):
             p.cpu_affinity([0, -1])
 
-    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason='not supported')
+    @pytest.mark.skipif(not HAS_CPU_AFFINITY, reason="not supported")
     def test_cpu_affinity_all_combinations(self):
         p = psutil.Process()
         initial = p.cpu_affinity()
diff --git a/psutil/tests/test_windows.py b/psutil/tests/test_windows.py
index 35387b2ce..da1da930b 100755
--- a/psutil/tests/test_windows.py
+++ b/psutil/tests/test_windows.py
@@ -107,7 +107,7 @@ def wmic(path, what, converter=int):
 class TestCpuAPIs(WindowsTestCase):
     @pytest.mark.skipif(
         'NUMBER_OF_PROCESSORS' not in os.environ,
-        reason='NUMBER_OF_PROCESSORS env var is not available',
+        reason="NUMBER_OF_PROCESSORS env var is not available",
     )
     def test_cpu_count_vs_NUMBER_OF_PROCESSORS(self):
         # Will likely fail on many-cores systems: