Refactor some certificate verification tests in preparation to adding

net/data/verify_certificate_chain_unittest/generate-expired-intermediate.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 1 intermediate, where the intermediate is expired
 (violates validity.notAfter). Verification is expected to fail."""
 
 import common
 
-# Self-signed root certificate (part of trust store).
+# Self-signed root certificate (used as trust anchor).
 root = common.create_self_signed_root_certificate('Root')
 root.set_validity_range(common.JANUARY_1_2015_UTC, common.JANUARY_1_2016_UTC)
 
 # Intermediate certificate.
 intermediate = common.create_intermediate_certificate('Intermediate', root)
 intermediate.set_validity_range(common.JANUARY_1_2015_UTC,
                                 common.MARCH_1_2015_UTC)
 
 # Target certificate.
 target = common.create_end_entity_certificate('Target', intermediate)
 target.set_validity_range(common.JANUARY_1_2015_UTC, common.JANUARY_1_2016_UTC)
 
-chain = [target, intermediate]
-trusted = [root]
+# Write the test chain to a file.
+test = common.TestData()
+test.description = __doc__
+test.chain = [target, intermediate]
+test.trust_anchor = common.TrustAnchor(root, constrained=False)
 
 # Both the root and target are valid at this time, however the
 # intermediate certificate is not.
-time = common.MARCH_2_2015_UTC
-verify_result = False
+test.utc_time = common.MARCH_2_2015_UTC
+test.verify_result = False
 
-common.write_test_file(__doc__, chain, trusted, time, verify_result)
+test.write_to_file(common.get_default_pem_path())