Refactor how net/data/verify_certificate_chain_unittest/*

net/data/verify_certificate_chain_unittest/generate-target-has-keycertsign-but-not-ca.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, a trusted root, and a target
-certificate that is not a CA, and yet has the keyCertSign bit set. Verification
-is expected to fail, since keyCertSign should only be asserted when CA is
-true."""
-
-import common
-
-# Self-signed root certificate (used as trust anchor).
-root = common.create_self_signed_root_certificate('Root')
-
-# Intermediate certificate.
-intermediate = common.create_intermediate_certificate('Intermediate', root)
-
-# Target certificate (end entity but has keyCertSign bit set).
-target = common.create_end_entity_certificate('Target', intermediate)
-target.get_extensions().set_property('keyUsage',
-    'critical,digitalSignature,keyEncipherment,keyCertSign')
-
-
-chain = [target, intermediate]
-trusted = common.TrustAnchor(root, constrained=False)
-time = common.DEFAULT_TIME
-key_purpose = common.DEFAULT_KEY_PURPOSE
-verify_result = False
-errors = """----- Certificate i=0 (CN=Target) -----
-ERROR: Target certificate looks like a CA but does not set all CA properties
-
-"""
-
-common.write_test_file(__doc__, chain, trusted, time, key_purpose,
-                       verify_result, errors)