libyang REFACTOR return values and options changes

Unified, all functions that return a variety
of errors return LY_ERR. Any options such as
NOSIBLINGS, WITHSIBLINGS and so on were replaced
by function variants with suffixes _single, _all,
_tree, and _siblings.
diff --git a/tests/utests/schema/test_schema.h b/tests/utests/schema/test_schema.h
index d0212fb..866e986 100644
--- a/tests/utests/schema/test_schema.h
+++ b/tests/utests/schema/test_schema.h
@@ -68,14 +68,14 @@
     { \
     const char *test_str__; \
     TEST_SCHEMA_STR(CTX, RFC7950, YIN, MOD_NAME, CONTENT, test_str__) \
-    assert_non_null(RESULT = lys_parse_mem(CTX, test_str__, YIN ? LYS_IN_YIN : LYS_IN_YANG)); \
+    assert_int_equal(LY_SUCCESS, lys_parse_mem(CTX, test_str__, YIN ? LYS_IN_YIN : LYS_IN_YANG, &(RESULT))); \
     }
 
 #define TEST_SCHEMA_ERR(CTX, RFC7950, YIN, MOD_NAME, CONTENT, ERRMSG) \
     { \
     const char *test_str__; \
     TEST_SCHEMA_STR(CTX, RFC7950, YIN, MOD_NAME, CONTENT, test_str__) \
-    assert_null(lys_parse_mem(CTX, test_str__, YIN ? LYS_IN_YIN : LYS_IN_YANG)); \
+    assert_int_not_equal(lys_parse_mem(CTX, test_str__, YIN ? LYS_IN_YIN : LYS_IN_YANG, NULL), LY_SUCCESS); \
     logbuf_assert(ERRMSG); \
     }