Feature/zephyr ztest (#118)

* Leverage (older) embedded unit tests into external unit tests build upon copy of Zephyr's ztest library and CMake.

* Expand top-level CMake build to run external unit tests.

* Expand Zephyr module extension to run external unit tests via west or sanitycheck.

Co-authored-by: Gregory Shue <gregory.shue@legrand.us>

test/bacnet/basic/sys/filename/src/main.c

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020 Legrand North America, LLC.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+/* @file
+ * @brief test BACnet integer encode/decode APIs
+ */
+
+#include <ztest.h>
+#include <bacnet/basic/sys/filename.h>
+
+/**
+ * @addtogroup bacnet_tests
+ * @{
+ */
+
+/**
+ * @brief Test
+ */
+static void testFilename(void)
+{
+    char *data1 = "c:\\Joshua\\run";
+    char *data2 = "/home/Anna/run";
+    char *data3 = "c:\\Program Files\\Christopher\\run.exe";
+    char *data4 = "//Mary/data/run";
+    char *data5 = "bin\\run";
+    char *filename = NULL;
+
+    filename = filename_remove_path(data1);
+    zassert_equal(strcmp("run", filename), 0, NULL);
+    filename = filename_remove_path(data2);
+    zassert_equal(strcmp("run", filename), 0, NULL);
+    filename = filename_remove_path(data3);
+    zassert_equal(strcmp("run.exe", filename), 0, NULL);
+    filename = filename_remove_path(data4);
+    zassert_equal(strcmp("run", filename), 0, NULL);
+    filename = filename_remove_path(data5);
+    zassert_equal(strcmp("run", filename), 0, NULL);
+
+    return;
+}
+/**
+ * @}
+ */
+
+
+void test_main(void)
+{
+    ztest_test_suite(filename_tests,
+     ztest_unit_test(testFilename)
+     );
+
+    ztest_run_test_suite(filename_tests);
+}