Make sparse array test immune to table hash order

The table hash function was changed in Lua 5.3 which swapped the JSON
object output order for the sparse array test. Ignore ordering
altogether by checking the JSON output type instead.

Author: mpx

tests/test.lua

@@ -10,6 +10,17 @@ local json = require "cjson"
 local json_safe = require "cjson.safe"
 local util = require "cjson.util"
 
+local function json_encode_output_type(value)
+    local text = json.encode(value)
+    if string.match(text, "{.*}") then
+        return "object"
+    elseif string.match(text, "%[.*%]") then
+        return "array"
+    else
+        return "scalar"
+    end
+end
+
 local function gen_raw_octets()
     local chars = {}
     for i = 0, 255 do chars[i + 1] = string.char(i) end
@@ -292,8 +303,8 @@ local cjson_tests = {
       json.encode, { { [1] = "one", [4] = "sparse test" } },
       true, { '["one",null,null,"sparse test"]' } },
     { "Encode sparse array as object",
-      json.encode, { { [1] = "one", [5] = "sparse test" } },
-      true, { '{"1":"one","5":"sparse test"}' } },
+      json_encode_output_type, { { [1] = "one", [5] = "sparse test" } },
+      true, { 'object' } },
     { "Encode table with numeric string key as object",
       json.encode, { { ["2"] = "numeric string key test" } },
       true, { '{"2":"numeric string key test"}' } },