Add MockChallengeResponseKey and additional composite key component test

tests/mock/MockChallengeResponseKey.h

@@ -0,0 +1,38 @@
+/*
+ *  Copyright (C) 2018 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program 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 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef KEEPASSXC_MOCKCHALLENGERESPONSEKEY_H
+#define KEEPASSXC_MOCKCHALLENGERESPONSEKEY_H
+
+#include "keys/ChallengeResponseKey.h"
+
+/**
+ * Mock challenge-response key implementation that simply returns the a fixed response.
+ */
+class MockChallengeResponseKey : public ChallengeResponseKey
+{
+public:
+    explicit MockChallengeResponseKey(const QByteArray& response);
+    ~MockChallengeResponseKey() override;
+    QByteArray rawKey() const override;
+    bool challenge(const QByteArray& challenge) override;
+
+private:
+    QByteArray m_response;
+};
+
+#endif //KEEPASSXC_MOCKCHALLENGERESPONSEKEY_H