os: Rename direcorty functions test.

os/test_dirs.py

@@ -1,6 +1,14 @@
 import os
 
+print(os.getcwd())
+
 l = os.listdir()
 print(l)
-assert "test_listdir.py" in l
+assert "test_dirs.py" in l
 assert "os" in l
+
+for t in os.walk("."):
+    print(t)
+
+for t in os.walk(".", False):
+    print(t)