ruff: add RET502 - [*] Do not implicitly return None in function ab…

…le to return non-`None` value

psutil/_psposix.py

@@ -119,7 +119,7 @@ def sleep(interval):
             # can't determine its exit status code.
             while _pid_exists(pid):
                 interval = sleep(interval)
-            return
+            return None
         else:
             if retpid == 0:
                 # WNOHANG flag was used and PID is still running.

psutil/tests/test_system.py

@@ -478,7 +478,7 @@ def test_per_cpu_times_2(self):
                 t1, t2 = psutil._cpu_busy_time(t1), psutil._cpu_busy_time(t2)
                 difference = t2 - t1
                 if difference >= 0.05:
-                    return
+                    return None
 
     @pytest.mark.skipif(
         CI_TESTING and OPENBSD, reason="unreliable on OPENBSD + CI"

pyproject.toml

@@ -23,6 +23,7 @@ select = [
     "D301",  # Use `r"""` if any backslashes in a docstring
     "D403",  # [*] First word of the first line should be capitalized
     "PERF102",  # [*] When using only the keys of a dict use the `keys()` method
+    "RET502",  # [*] Do not implicitly `return None` in function able to return non-`None` value
     "RET506",  # [*] Unnecessary `else` after `raise` statement
     "RET507",  # Unnecessary `elif` after `continue` statement
     "S113",  # Probable use of requests call without timeout

scripts/fans.py

@@ -23,7 +23,7 @@ def main():
     fans = psutil.sensors_fans()
     if not fans:
         print("no fans detected")
-        return
+        return None
     for name, entries in fans.items():
         print(name)
         for entry in entries: