Enable dynamic BACnet POSIX files for example (#374)

* Enable dynamic BACnet POSIX files for example

* Add basic unit test for BACnet File object.

* Use example file pathname in demo app.

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

test/bacnet/basic/object/bacfile/src/main.c

@@ -0,0 +1,75 @@
+/**
+ * @file
+ * @brief Test for BACnet File object
+ * @author Steve Karg <skarg@users.sourceforge.net>
+ * @date January 2023
+ * @section LICENSE
+ *
+ * Copyright (C) 2022 Steve Karg <skarg@users.sourceforge.net>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+#include <ztest.h>
+#include <bacnet/basic/object/bacfile.h>
+
+/**
+ * @addtogroup bacnet_tests
+ * @{
+ */
+
+/**
+ * @brief Test
+ */
+static void test_BACnet_File_Object(void)
+{
+    uint8_t apdu[MAX_APDU] = { 0 };
+    int len = 0, test_len = 0;
+    BACNET_READ_PROPERTY_DATA rpdata = { 0 };
+    BACNET_APPLICATION_DATA_VALUE value = {0};
+    const int *required_property = NULL;
+    const uint32_t instance = 1;
+
+    bacfile_init();
+    bacfile_create(1);
+    rpdata.application_data = &apdu[0];
+    rpdata.application_data_len = sizeof(apdu);
+    rpdata.object_type = OBJECT_FILE;
+    rpdata.object_instance = instance;
+    rpdata.array_index = BACNET_ARRAY_ALL;
+
+    BACfile_Property_Lists(&required_property, NULL, NULL);
+    while ((*required_property) >= 0) {
+        rpdata.object_property = *required_property;
+        len = bacfile_read_property(&rpdata);
+        if (len < 0) {
+            printf("property %u: failed to read!\n",
+                (unsigned)rpdata.object_property);
+        }
+        zassert_true(len >= 0, NULL);
+        if (len >= 0) {
+            test_len = bacapp_decode_known_property(rpdata.application_data,
+                len, &value, rpdata.object_type, rpdata.object_property);
+            if (len != test_len) {
+                printf("property %u: failed to decode!\n",
+                    (unsigned)rpdata.object_property);
+            }
+            zassert_equal(len, test_len, NULL);
+        }
+        required_property++;
+    }
+
+    return;
+}
+/**
+ * @}
+ */
+
+
+void test_main(void)
+{
+    ztest_test_suite(bacfile_tests,
+     ztest_unit_test(test_BACnet_File_Object)
+     );
+
+    ztest_run_test_suite(bacfile_tests);
+}