add snowflake unit tests

tests/deps.ts

@@ -2,5 +2,6 @@ export {
   assertArrayIncludes,
   assertEquals,
   assertExists,
+  assertNotEquals,
   assertThrows,
 } from "https://deno.land/std@0.113.0/testing/asserts.ts";

tests/local/snowflake.ts

@@ -1,9 +1,20 @@
-import { snowflakeToBigint } from "../../src/util/bigint.ts";
+import { bigintToSnowflake, snowflakeToBigint } from "../../src/util/bigint.ts";
-import { assertEquals } from "../deps.ts";
+import { assertEquals, assertNotEquals } from "../deps.ts";
 
-Deno.test("[Local Test] - snowflakeToBigint ", async (t) => {
+Deno.test("[Local Test] - snowflakeToBigint ", () => {
   const text = "130136895395987456";
   const big = 130136895395987456n;
+  const result = snowflakeToBigint(text);
 
-  assertEquals(big, snowflakeToBigint(text));
+  assertEquals(big, result);
+  assertNotEquals(text, result);
+});
+
+Deno.test("[Local Test] - bigIntToSnowflake", () => {
+  const text = "130136895395987456";
+  const big = 130136895395987456n;
+  const result = bigintToSnowflake(big);
+
+  assertEquals(text, result);
+  assertNotEquals(big, result);
 });