vfs: add test for errno value after 'open'

components/vfs/test/test_vfs_open.c

@@ -0,0 +1,38 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "esp_vfs.h"
+#include "unity.h"
+
+static int open_errno_test_open(const char * path, int flags, int mode)
+{
+    errno = EIO;
+    return -1;
+}
+
+TEST_CASE("esp_vfs_open sets correct errno", "[vfs]")
+{
+    esp_vfs_t desc = {
+        .open = open_errno_test_open
+    };
+    TEST_ESP_OK(esp_vfs_register("/test", &desc, NULL));
+
+    int fd = open("/test/path", 0, 0);
+    int e = errno;
+    TEST_ASSERT_EQUAL(-1, fd);
+    TEST_ASSERT_EQUAL(EIO, e);
+
+    fd = open("/nonexistent/path", 0, 0);
+    e = errno;
+    TEST_ASSERT_EQUAL(-1, fd);
+    TEST_ASSERT_EQUAL(ENOENT, e);
+
+    TEST_ESP_OK(esp_vfs_unregister("/test"));
+}