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_printer_yang.c b/tests/utests/schema/test_printer_yang.c
index 6352695..66d3d6b 100644
--- a/tests/utests/schema/test_printer_yang.c
+++ b/tests/utests/schema/test_printer_yang.c
@@ -137,7 +137,7 @@
     assert_int_equal(LY_SUCCESS, ly_out_new_memory(&printed, 0, &out));
     assert_int_equal(LY_SUCCESS, ly_ctx_new(NULL, 0, &ctx));
 
-    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_parse_mem(ctx, orig, LYS_IN_YANG, &mod));
     assert_int_equal(LY_SUCCESS, lys_print(out, mod, LYS_OUT_YANG, 0, 0));
     assert_int_equal(strlen(orig), ly_out_printed(out));
     assert_string_equal(printed, orig);
@@ -188,7 +188,7 @@
             "    if-feature \"not f1\";\n"
             "  }\n"
             "}\n";
-    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_parse_mem(ctx, orig, LYS_IN_YANG, &mod));
     assert_int_equal(LY_SUCCESS, lys_print(out, mod, LYS_OUT_YANG, 0, 0));
     assert_int_equal(strlen(orig), ly_out_printed(out));
     assert_string_equal(printed, orig);
@@ -215,7 +215,7 @@
             "    status obsolete;\n"
             "  }\n"
             "}\n";
-    assert_non_null(mod = lys_parse_mem(ctx, orig, LYS_IN_YANG));
+    assert_int_equal(LY_SUCCESS, lys_parse_mem(ctx, orig, LYS_IN_YANG, &mod));
     assert_int_equal(LY_SUCCESS, lys_print(out, mod, LYS_OUT_YANG, 0, 0));
     assert_int_equal(strlen(orig), ly_out_printed(out));
     assert_string_equal(printed, orig);