Add test for pylint plugins

Author: proteusvacuum

tests/fixtures/pylint/has_errors.py

@@ -12,3 +12,5 @@ def thing_two(arg1, arg2, arg3):
     result=arg1*arg2
     if result == arg1:
         pass
+    elif result == '':
+        pass

tests/fixtures/pylint/sample_rcfile

@@ -1,3 +1,6 @@
+[MASTER]
+load-plugins=pylint.extensions.emptystring
+
 [MESSAGES CONTROL]
 
 disable=W0611,

tests/tools/test_pylint.py

@@ -123,6 +123,7 @@ def test_process_files__config(self):
         problems = self.problems.all(self.fixtures[1])
         eq_([
             Comment(filename, 10, 10, "C0301 Line too long (51/50)"),
-            Comment(filename, 1, 1, "C0302 Too many lines in module (14/3)"),
+            Comment(filename, 1, 1, "C0302 Too many lines in module (16/3)"),
             Comment(filename, 9, 9, "R0913 Too many arguments (3/1)"),
+            Comment(filename, 15, 15, "C1901 Avoid comparisons to empty string"),
         ], problems)