Issue#5 Fix for zero noc and loc

Author: matsoftware

swift_code_metrics/_metrics.py

@@ -114,7 +114,10 @@ def percentage_of_comments(noc, loc):
         :param loc: the number of lines of code
         :return: The POC value (double)
         """
-        return 100 * noc / (noc + loc)
+        noc_loc = noc + loc
+        if noc_loc == 0:
+            return 0
+        return 100 * noc / noc_loc
 
     # Analysis
 

swift_code_metrics/tests/test_metrics.py

@@ -111,6 +111,12 @@ def test_total_dependencies(self):
         self.assertEqual(expected_deps,
                          Metrics.total_dependencies(self.foundation_kit))
 
+    def test_poc_valid_loc_noc(self):
+        self.assertEqual(50, Metrics.percentage_of_comments(loc=2, noc=2))
+
+    def test_poc_invalid_loc_noc(self):
+        self.assertEqual(0, Metrics.percentage_of_comments(loc=0, noc=0))
+
     @property
     def __dummy_external_frameworks(self):
         return [