tests/drivers/flash: Add test case for flash_get_size

Add flash_get_size commit and Kconfig option for test to set the
expected size of device.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

tests/drivers/flash/common/Kconfig

@@ -0,0 +1,14 @@
+# Copyright (c) 2024, Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+# Device/scenario dependent information that is not available in
+# other ways.
+
+config TEST_DRIVER_FLASH_SIZE
+	int "Size of flash device under test"
+	default -1
+	help
+	  Expected flash device size the test will validate against. If the flash driver does not
+	  support the get_size() API, leave this set as -1 to skip the test.
+
+source "Kconfig.zephyr"

tests/drivers/flash/common/src/main.c

@@ -325,6 +325,19 @@ static bool flash_callback(const struct flash_pages_info *info, void *data)
 	return true;
 }
 
+ZTEST(flash_driver, test_get_size)
+{
+#if CONFIG_TEST_DRIVER_FLASH_SIZE != -1
+	uint64_t size;
+
+	zassert_ok(flash_get_size(flash_dev, &size));
+	zassert_equal(size, CONFIG_TEST_DRIVER_FLASH_SIZE, "Unexpected size");
+#else
+	/* The test is sipped only because there is no uniform way to get device size */
+	ztest_test_skip();
+#endif
+}
+
 ZTEST(flash_driver, test_flash_page_layout)
 {
 	int rc;