[feaLib] Add an ast test for the previous commit

Tests/feaLib/ast_test.py

@@ -0,0 +1,17 @@
+from __future__ import print_function, division, absolute_import
+from __future__ import unicode_literals
+from fontTools.feaLib import ast
+import unittest
+
+
+class AstTest(unittest.TestCase):
+    def test_glyphname_escape(self):
+        statement = ast.GlyphClass()
+        for name in ("BASE", "NULL", "foo", "a"):
+            statement.append(ast.GlyphName(name))
+        self.assertEqual(statement.asFea(), r"[\BASE \NULL foo a]")
+
+
+if __name__ == "__main__":
+    import sys
+    sys.exit(unittest.main())