tests: add qPrefFacebook testcases

add test cases to secure struct preferences and qPrefFacebook work together

Signed-off-by: Jan Iversen <jani@apache.org>

tests/testqPrefFacebook.h

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef TESTQPREFFACEBOOK_H
+#define TESTQPREFFACEBOOK_H
+
+#include <QObject>
+
+class TestQPrefFacebook : public QObject
+{
+	Q_OBJECT
+
+private slots:
+	void initTestCase();
+	void test_struct_get();
+	void test_set_struct();
+	void test_multiple();
+};
+
+#endif // TESTQPREFFACEBOOK_H