imorove test coverage

2 files changed, 7 insertions, 1 deletions

diff --git a/psutil/_common.py b/psutil/_common.py
index 13e6a828..c90b0ba5 100644
--- a/psutil/_common.py
+++ b/psutil/_common.py
@@ -92,7 +92,7 @@ def usage_percent(used, total, _round=None):
     try:
         ret = (used / total) * 100
     except ZeroDivisionError:
-        ret = 0
+        ret = 0.0 if isinstance(used, float) or isinstance(total, float) else 0
     if _round is not None:
         return round(ret, _round)
     else:
diff --git a/psutil/tests/test_process.py b/psutil/tests/test_process.py
index ecf99723..0fc27940 100644
--- a/psutil/tests/test_process.py
+++ b/psutil/tests/test_process.py
@@ -154,6 +154,12 @@ class TestProcess(unittest.TestCase):
                 with self.assertRaises(psutil.AccessDenied):
                     psutil.Process().send_signal(sig)
                 assert fun.called
+            # Sending a signal to process with PID 0 is not allowed as
+            # it would affect every process in the process group of
+            # the calling process (os.getpid()) instead of PID 0").
+            if 0 in psutil.pids():
+                p = psutil.Process(0)
+                self.assertRaises(ValueError, p.send_signal, signal.SIGTERM)
 
     def test_wait(self):
         # check exit code signal