implement basic unit testing

tests/Makefile

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+#
+# Makefile
+#
+
+include ../config.mk
+
+all: unit-tests.c
+	$(CC) unit-tests.c -o test-suite -lcunit -lconfig ../build/libglacier.a -Wall -Wextra
+	./test-suite

tests/unit-tests.c

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+/*
+ * 	unit-tests.c - Unit tests for libglacier
+ *
+ * 	This file is part of Glacier.
+ *
+ * 	Glacier 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.
+ *
+ * 	Glacier 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 Glacier. If
+ * 	not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <libconfig.h>
+#include <unistd.h>
+
+#include "../include/config.h"
+#include "../include/log.h"
+#include "../include/pkgops.h"
+#include "../include/runtime.h"
+#include "../include/security.h"
+
+#include <CUnit/Basic.h>
+
+void
+test_is_process_root(void)
+{
+	CU_ASSERT(is_process_root() == 0);
+
+	uid_t saved_uid = getuid();
+	setuid(0);
+	CU_ASSERT(is_process_root() == 1);
+
+	setuid((int)saved_uid);
+}
+
+int
+main()
+{
+	if (CUE_SUCCESS != CU_initialize_registry()) {
+		return CU_get_error();
+	}
+
+	CU_basic_set_mode(CU_BRM_VERBOSE);
+
+	CU_basic_run_tests();
+	return CU_get_error();
+}