Make sure there are no Nones in our list

diff_cover/tests/test_violations_reporter.py

@@ -6,6 +6,7 @@
 import xml.etree.cElementTree as etree
 from subprocess import Popen
 from textwrap import dedent
+
 import mock
 
 import six
@@ -120,6 +121,32 @@ def test_non_python_violations(self):
             )
         )
 
+    def test_non_python_violations_empty_path(self):
+        """
+        In the wild empty sources can happen. See https://github.com/Bachmann1234/diff-cover/issues/88
+        Best I can tell its mostly irrelevant but I mostly dont want it crashing
+        """
+
+        xml = etree.fromstring('''
+        <coverage line-rate="0.178" branch-rate="0.348" version="1.9" timestamp="1545037553" lines-covered="675" lines-valid="3787" branches-covered="260" branches-valid="747">
+        <sources>
+        <source></source>
+        </sources>
+        </coverage>
+        ''')
+
+        coverage = XmlCoverageReporter([xml])
+
+        self.assertEqual(
+            set(),
+            coverage.violations('')
+        )
+
+        self.assertEqual(
+            set(),
+            coverage.measured_lines('')
+        )
+
     def test_two_inputs_first_violate(self):
 
         # Construct the XML report

diff_cover/violationsreporters/violations_reporter.py

@@ -76,7 +76,7 @@ def _get_classes(self, xml_document, src_path):
         # cobertura sometimes provides the sources for the measurements
         # within it. If we have that we outta use it
         sources = xml_document.findall('sources/source')
-        sources = [source.text for source in sources]
+        sources = [source.text for source in sources if source.text]
         classes = [class_tree
                    for class_tree in xml_document.findall(".//class")
                    or []]