Fix and Improve TryToRoman unittest

1) Don't break when the roman module is not found
2) Test that not finding the roman module doesn't make TryToRoman fail
(currently that is the case)

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

test/ganeti.compat_unittest.py

@@ -61,11 +61,31 @@ class TestPartial(testutils.GanetiTestCase):
 class TestTryToRoman(testutils.GanetiTestCase):
   """test the compat.TryToRoman function"""
 
+  def setUp(self):
+    testutils.GanetiTestCase.setUp(self)
+    # Save the compat.roman module so we can alter it with a fake...
+    self.compat_roman_module = compat.roman
+
+  def tearDown(self):
+    # ...and restore it at the end of the test
+    compat.roman = self.compat_roman_module
+    testutils.GanetiTestCase.tearDown(self)
+
   def testAFewIntegers(self):
+    # This test only works is the roman module is installed
+    if compat.roman is not None:
+      self.assertEquals(compat.TryToRoman(0), 0)
+      self.assertEquals(compat.TryToRoman(1), "I")
+      self.assertEquals(compat.TryToRoman(4), "IV")
+      self.assertEquals(compat.TryToRoman(5), "V")
+
+  def testWithNoRoman(self):
+    # compat.roman is saved/restored in setUp/tearDown
+    compat.roman = None
     self.assertEquals(compat.TryToRoman(0), 0)
-    self.assertEquals(compat.TryToRoman(1), "I")
-    self.assertEquals(compat.TryToRoman(4), "IV")
-    self.assertEquals(compat.TryToRoman(5), "V")
+    self.assertEquals(compat.TryToRoman(1), 1)
+    self.assertEquals(compat.TryToRoman(4), 4)
+    self.assertEquals(compat.TryToRoman(5), 5)
 
   def testStrings(self):
     self.assertEquals(compat.TryToRoman("astring"), "astring")