add test for PathMapper bug

Author: mr-c

tests/test_pathmapper.py

@@ -0,0 +1,21 @@
+import unittest
+import json
+import cwltool.draft2tool as tool
+import cwltool.expression as expr
+import cwltool.factory
+from cwltool.pathmapper import PathMapper
+
+
+class TestPathMapper(unittest.TestCase):
+
+    def test_subclass(self):
+        
+        class SubPathMapper(PathMapper):
+
+            def __init__(self, referenced_files, basedir, new):
+                super(PathMapper, self).__init__(referenced_files, basedir)
+                self.new = new
+
+        a = SubPathMapper([], '', "new")
+        self.assertTrue(a.new, "new")
+