test_dump({a => 1}, "{}", {skip_keys => ['a']});
test_dump({a => 1}, "{}", {skip_keys => {a=>1}});
-test_dump({2 => 1, _a => 1}, "{2:1,\"_a\":1}", {pretty=>0});
-test_dump({2 => 1, _a => 1}, "{2:1}", {pretty=>0, skip_keys_qr => qr/^_/});
+test_dump({2 => 1, _a => 1}, "{\"2\":1,\"_a\":1}", {pretty=>0});
+test_dump({2 => 1, _a => 1}, "{\"2\":1}", {pretty=>0, skip_keys_qr => qr/^_/});
test_dump({a => 1}, "{\n \"a\" : 1\n}", {pretty => 1});
test_dump({a => 1}, "{\n \"a\" : 1\n}", {pretty => 1, hash_nl => "\n", hash_sep => " : ", indent => " "});