tests: sync common testing infrastructure with ndn-cxx

Change-Id: I1bd56d472f5627207f17c950eb4c5550d1b3724c
diff --git a/tests/key-chain-fixture.hpp b/tests/key-chain-fixture.hpp
new file mode 100644
index 0000000..c785871
--- /dev/null
+++ b/tests/key-chain-fixture.hpp
@@ -0,0 +1,85 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2022 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDNCERT_TESTS_KEY_CHAIN_FIXTURE_HPP
+#define NDNCERT_TESTS_KEY_CHAIN_FIXTURE_HPP
+
+#include "detail/ndncert-common.hpp"
+
+#include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/security/signing-helpers.hpp>
+
+namespace ndncert::tests {
+
+/**
+ * @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 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 Name& identityName, const std::string& filename,
+                   bool allowCreate = false);
+
+protected:
+  KeyChainFixture();
+
+  ~KeyChainFixture();
+
+protected:
+  ndn::KeyChain m_keyChain;
+
+private:
+  std::vector<std::string> m_certFiles;
+};
+
+} // namespace ndncert::tests
+
+#endif // NDNCERT_TESTS_KEY_CHAIN_FIXTURE_HPP