tests: sync common testing infrastructure with ndn-cxx

Change-Id: I1e5cdcda8f6d3d9f9addc7a9f17359aedef9db7e
diff --git a/tests/key-chain-fixture.hpp b/tests/key-chain-fixture.hpp
new file mode 100644
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+++ b/tests/key-chain-fixture.hpp
@@ -0,0 +1,102 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2022,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NLSR (Named-data Link State Routing).
+ * See AUTHORS.md for complete list of NLSR authors and contributors.
+ *
+ * NLSR is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NLSR is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NLSR_TESTS_KEY_CHAIN_FIXTURE_HPP
+#define NLSR_TESTS_KEY_CHAIN_FIXTURE_HPP
+
+#include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/security/signing-helpers.hpp>
+
+namespace nlsr {
+namespace test {
+
+/**
+ * @brief A fixture providing an in-memory KeyChain.
+ *
+ * Test cases can use this fixture to create identities. Identities, certificates, and
+ * saved certificates are automatically removed during test teardown.
+ */
+class KeyChainFixture
+{
+protected:
+  using Certificate = ndn::security::Certificate;
+  using Identity    = ndn::security::Identity;
+  using Key         = ndn::security::Key;
+
+public:
+  /**
+   * @brief Saves an NDN certificate to a file
+   * @return true if successful, false otherwise
+   */
+  bool
+  saveCert(const ndn::Data& cert, const std::string& filename);
+
+  /**
+   * @brief Saves the default certificate of @p identity to a file
+   * @return true if successful, false otherwise
+   */
+  bool
+  saveIdentityCert(const Identity& identity, const std::string& filename);
+
+  /**
+   * @brief Saves the default certificate of the identity named @p identityName to a file
+   * @param identityName Name of the identity
+   * @param filename File name, must be writable
+   * @param allowCreate If true, create the identity if it does not exist
+   * @return true if successful, false otherwise
+   */
+  bool
+  saveIdentityCert(const ndn::Name& identityName, const std::string& filename,
+                   bool allowCreate = false);
+
+  /**
+   * @brief Issue a certificate for \p subidentityName signed by \p issuer
+   *
+   * If identity does not exist, it is created.
+   * A new key is generated as the default key for identity.
+   * A default certificate for the key is signed by the issuer using its default certificate.
+   *
+   * @return the sub identity
+   */
+  Identity
+  addSubCertificate(const ndn::Name& identityName, const Identity& issuer,
+                    const ndn::KeyParams& params = ndn::KeyChain::getDefaultKeyParams());
+
+protected:
+  KeyChainFixture();
+
+  ~KeyChainFixture();
+
+protected:
+  ndn::KeyChain m_keyChain;
+
+private:
+  std::vector<std::string> m_certFiles;
+};
+
+} // namespace test
+} // namespace nlsr
+
+#endif // NLSR_TESTS_KEY_CHAIN_FIXTURE_HPP