--- a/RegressionTests__TimeAndDateTest.st	Mon Nov 10 16:18:55 2014 +0100
+++ b/RegressionTests__TimeAndDateTest.st	Mon Nov 10 18:07:48 2014 +0100
@@ -641,6 +641,53 @@
     "
      self new test_13_timestampQueries
     "
+!
+
+test_14_arithmetic
+    |t1 t2 t3 s|
+
+    t1 := UtcTimestamp newDay:1 month:1 year:2000.
+    t2 := t1 addDays:1.
+    self assert:(t2 - t1) days = 1.
+
+    t2 := t1 addHours:1.
+    self assert:(t2 - t1) hours = 1.
+
+    t2 := t1 addSeconds:1.
+    self assert:(t2 - t1) seconds = 1.
+
+    t1 := UtcTimestamp readFrom:'20000102T133045Z'.
+    t2 := t1 addDays:1.            
+    self assert:(t2 printString = '2000-01-03 13:30:45Z').
+
+    t1 := Timestamp readFrom:'20000102T133045+01'.
+    t2 := t1 addDays:1.            
+    self assert:(t2 printString = '2000-01-03 13:30:45+01').
+
+    t1 := UtcTimestamp readFrom:'20000102T133045Z'.
+    t2 := Timestamp readFrom:'20000102T133045Z'. 
+    self assert:(t1 = t2).
+
+    t2 := Timestamp readFrom:'20000102T143045+01'. 
+    self assert:(t1 = t2).
+
+    t2 := Timestamp readFrom:'20000102T123045-01'. 
+    self assert:(t1 = t2).
+
+    t2 := Timestamp readFrom:'20000102T123045'.     "/ a local one
+    s := t2 storeString.
+    t3 := Timestamp readFrom:s.
+
+    self assert:(t2 = t3).
+
+    t1 := TZTimestamp readFrom:'20000102T133045Z'.
+    self assert:(t1 printString = '2000-01-02 13:30:45+00').
+    t1 := UtcTimestamp readFrom:'20000102T133045Z'.
+    self assert:(t1 printString = '2000-01-02 13:30:45Z').
+
+    "
+     self new test_14_arithmetic         
+    "
 ! !
 
 !TimeAndDateTest class methodsFor:'documentation'!