Improve signal test

tests/snippets/stdlib_signal.py

@@ -1,5 +1,8 @@
 import signal
 import time
+from testutils import assert_raises
+
+assert_raises(TypeError, lambda: signal.signal(signal.SIGINT, 2))
 
 signals = []
 
@@ -7,10 +10,24 @@ def handler(signum, frame):
 	signals.append(signum)
 
 
-signal.signal(14, handler)
-assert signal.getsignal(14) is handler
+signal.signal(signal.SIGALRM, handler)
+assert signal.getsignal(signal.SIGALRM) is handler
+
+signal.alarm(1)
+time.sleep(2.0)
+assert signals == [signal.SIGALRM]
+
+signal.signal(signal.SIGALRM, signal.SIG_IGN)
+signal.alarm(1)
+time.sleep(2.0)
+
+assert signals == [signal.SIGALRM]
+
+signal.signal(signal.SIGALRM, handler)
+signal.alarm(1)
+time.sleep(2.0)
+
+assert signals == [signal.SIGALRM, signal.SIGALRM]
+
 
-signal.alarm(2)
-time.sleep(3.0)
-assert signals == [14]