alarms: add a couple of unit tests

basis/alarms/alarms-tests.factor

@@ -1,5 +1,6 @@
 USING: alarms alarms.private kernel calendar sequences
-tools.test threads concurrency.count-downs ;
+tools.test threads concurrency.count-downs concurrency.promises
+fry tools.time math ;
 IN: alarms.tests
 
 [ ] [
@@ -14,3 +15,17 @@ IN: alarms.tests
     self [ resume ] curry instant later drop
     "test" suspend drop
 ] unit-test
+
+[ t ] [
+    [
+        <promise>
+        '[ t _ fulfill ] 5 seconds later drop
+    ] benchmark 4,000,000,000 >
+] unit-test
+
+[ { 3 } ] [
+    { 3 } dup
+    '[ 4 _ set-first ] 2 seconds later
+    1/2 seconds sleep
+    cancel-alarm
+] unit-test