Add a forgotten test module, test_sys_path.py and fix Python2/3 compatibility issues.

test/test_evaluate/test_sys_path.py

@@ -0,0 +1,16 @@
+from jedi._compatibility import unicode
+from jedi.parser import Parser
+from jedi.evaluate import sys_path, Evaluator
+
+
+def test_paths_from_assignment():
+    def paths(src):
+        stmt = Parser(unicode(src)).module.statements[0]
+        return list(sys_path._paths_from_assignment(Evaluator(), stmt))
+
+    assert paths('sys.path[0:0] = ["a"]') == ['a']
+    assert paths('sys.path = ["b", 1, x + 3, y, "c"]') == ['b', 'c']
+    assert paths('sys.path = a = ["a"]') == ['a']
+
+    # Fail for complicated examples.
+    assert paths('sys.path, other = ["a"], 2') == []