tests: flash_map: Add tests for subpartitions

Add additional tests for subpartitions support in flash_map macros.

Signed-off-by: Tomasz Chyrowicz <tomasz.chyrowicz@nordicsemi.no>

Author: tomchy

tests/subsys/storage/flash_map/src/main.c

@@ -184,6 +184,44 @@ ZTEST(flash_map, test_fixed_partition_node_macros)
 #endif
 }
 
+ZTEST(flash_map, test_fixed_subpartition_node_macros)
+{
+	/* DTS node macros, for accessing fixed partitions, are only available
+	 * for DTS based partitions; custom flash map may define partition outside
+	 * of DTS definition, making the NODE macros fail to evaluate.
+	 */
+#if defined(CONFIG_TEST_FLASH_MAP_NODE_MACROS)
+	/* Test that both partitions and subpartitions exist */
+	zassert_true(FIXED_PARTITION_EXISTS(disabled_a));
+	zassert_true(FIXED_PARTITION_EXISTS(disabled_a_a));
+	zassert_true(FIXED_PARTITION_EXISTS(disabled_a_b));
+
+	/* Test that the subpartition offset is relative to the parent */
+	zassert_equal(FIXED_PARTITION_OFFSET(disabled_b),
+		      FIXED_PARTITION_OFFSET(disabled_b_a));
+	zassert_equal(FIXED_PARTITION_OFFSET(disabled_b) + 0x100,
+		      FIXED_PARTITION_OFFSET(disabled_b_b));
+	zassert_equal(FIXED_PARTITION_NODE_OFFSET(DT_NODELABEL(disabled_b)),
+		      FIXED_PARTITION_NODE_OFFSET(DT_NODELABEL(disabled_b_a)));
+	zassert_equal(
+		FIXED_PARTITION_NODE_OFFSET(DT_NODELABEL(disabled_b)) + 0x100,
+		FIXED_PARTITION_NODE_OFFSET(DT_NODELABEL(disabled_b_b)));
+
+	/* Test that the subpartition address is relative to the parent */
+	zassert_equal(FIXED_PARTITION_ADDRESS(disabled_b),
+		      FIXED_PARTITION_ADDRESS(disabled_b_a));
+	zassert_equal(FIXED_PARTITION_ADDRESS(disabled_b) + 0x100,
+		      FIXED_PARTITION_ADDRESS(disabled_b_b));
+	zassert_equal(FIXED_PARTITION_NODE_ADDRESS(DT_NODELABEL(disabled_b)),
+		      FIXED_PARTITION_NODE_ADDRESS(DT_NODELABEL(disabled_b_a)));
+	zassert_equal(
+		FIXED_PARTITION_NODE_ADDRESS(DT_NODELABEL(disabled_b)) + 0x100,
+		FIXED_PARTITION_NODE_ADDRESS(DT_NODELABEL(disabled_b_b)));
+#else
+	ztest_test_skip();
+#endif
+}
+
 ZTEST(flash_map, test_flash_area_erase_and_flatten)
 {
 	int i;