Refactor how net/data/verify_certificate_chain_unittest/*

net/data/verify_certificate_chain_unittest/basic-constraints-pathlen-0-self-issued/generate-chains.py

 #!/usr/bin/python
 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Certificate chain with 2 intermediates. The first intermediate has a basic
 constraints path length of 0. The second one is self-issued so does not count
 against the path length."""
 
+import sys
+sys.path += ['..']
+
 import common
 
 # Self-signed root certificate (used as trust anchor).
 root = common.create_self_signed_root_certificate('Root')
 
 # Intermediate with pathlen 0
 intermediate1 = common.create_intermediate_certificate('Intermediate', root)
 intermediate1.get_extensions().set_property('basicConstraints',
                                             'critical,CA:true,pathlen:0')
 
 # Another intermediate (with the same pathlen restriction).
 # Note that this is self-issued but NOT self-signed.
 intermediate2 = common.create_intermediate_certificate('Intermediate',
                                                        intermediate1)
 intermediate2.get_extensions().set_property('basicConstraints',
                                             'critical,CA:true,pathlen:0')
 
 # Target certificate.
 target = common.create_end_entity_certificate('Target', intermediate2)
 
-chain = [target, intermediate2, intermediate1]
-trusted = common.TrustAnchor(root, constrained=False)
-time = common.DEFAULT_TIME
-key_purpose = common.DEFAULT_KEY_PURPOSE
-verify_result = True
-errors = None
-
-common.write_test_file(__doc__, chain, trusted, time, key_purpose,
-                       verify_result, errors)
+chain = [target, intermediate2, intermediate1, root]
+common.write_chain(__doc__, chain, 'chain.pem')