feat: add sync validation

src/__tests__/sync/validate.spec.luau

@@ -0,0 +1,30 @@
+local validate = require(script.Parent.Parent.Parent.sync.validate)
+
+return function()
+	it("validates inputs", function()
+		local cases = {
+			array = { value = { 1, 2, 3 }, expected = true },
+			array_sparse = { value = { 1, nil :: any, 3 }, expected = true },
+			array_sparse_invalid = { value = { [1] = 0, [3] = 0 }, expected = false },
+
+			map_decimal_key = { value = { [1.5] = 0 }, expected = false },
+			map_mixed_key = { value = { [1] = 0, a = 0 }, expected = false },
+
+			number = { value = 1, expected = true },
+			number_infinity = { value = math.huge, expected = false },
+			number_nan = { value = 0 / 0, expected = false },
+		}
+
+		for key, case in pairs(cases) do
+			local success, result = pcall(function()
+				validate(case.value, key, error)
+			end)
+
+			if case.expected and not success then
+				error(`Expected {key} to be valid, threw {result}`)
+			elseif not case.expected and success then
+				error(`Expected {key} to be invalid, but it was valid`)
+			end
+		end
+	end)
+end