Rename invalid_urls -> invalid_strings, add examples back

This restores some coverage

Author: jameshiew

test/conftest.py

@@ -262,5 +262,5 @@ def git_urls():
 
 
 @pytest.fixture()
-def invalid_urls():
-    return []
+def invalid_strings():
+    return ['', 'not a valid URL']

test/test_parser.py

@@ -41,9 +41,9 @@ def test_parse(git_urls):
         assert d['owner'] == result.owner
 
 
-def test_parse_raises_on_invalid_url(invalid_urls):
-    for url in invalid_urls:
-        p = parser.Parser(url)
+def test_parse_raises_on_invalid_string(invalid_strings):
+    for invalid_string in invalid_strings:
+        p = parser.Parser(invalid_string)
         with pytest.raises(parser.ParserError):
             p.parse()