diff --git a/utils/transform.test.ts b/utils/transform.test.ts
new file mode 100644
index 0000000..ffc2e69
--- /dev/null
+++ b/utils/transform.test.ts
@@ -0,0 +1,277 @@
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-var-requires */
+import { stringify } from "./transform";
+
+describe("stringify", () => {
+  describe("primitive types", () => {
+    it("should stringify strings", () => {
+      expect(stringify("hello")).toBe(JSON.stringify("hello"));
+      expect(stringify("")).toBe(JSON.stringify(""));
+      expect(stringify("with spaces")).toBe(JSON.stringify("with spaces"));
+    });
+
+    it("should stringify numbers", () => {
+      expect(stringify(42)).toBe(JSON.stringify(42));
+      expect(stringify(0)).toBe(JSON.stringify(0));
+      expect(stringify(-1)).toBe(JSON.stringify(-1));
+      expect(stringify(3.14)).toBe(JSON.stringify(3.14));
+      expect(stringify(Infinity)).toBe(JSON.stringify(Infinity));
+      expect(stringify(-Infinity)).toBe(JSON.stringify(-Infinity));
+      expect(stringify(NaN)).toBe(JSON.stringify(NaN));
+    });
+
+    it("should stringify booleans", () => {
+      expect(stringify(true)).toBe(JSON.stringify(true));
+      expect(stringify(false)).toBe(JSON.stringify(false));
+    });
+
+    it("should stringify null and undefined", () => {
+      expect(stringify(null)).toBe(JSON.stringify(null));
+      expect(stringify(undefined)).toBe(JSON.stringify(undefined));
+    });
+  });
+
+  describe("bigint handling", () => {
+    it("should stringify bigint with n suffix", () => {
+      expect(stringify(BigInt(123))).toBe('"123n"');
+      expect(stringify(BigInt(0))).toBe('"0n"');
+      expect(stringify(BigInt(-456))).toBe('"-456n"');
+    });
+
+    it("should stringify large bigint values", () => {
+      const largeBigInt = BigInt("9007199254740991");
+      expect(stringify(largeBigInt)).toBe('"9007199254740991n"');
+
+      const veryLargeBigInt = BigInt("123456789012345678901234567890");
+      expect(stringify(veryLargeBigInt)).toBe(
+        '"123456789012345678901234567890n"'
+      );
+    });
+
+    it("should stringify objects containing bigint", () => {
+      const obj = { id: BigInt(123), name: "test" };
+      expect(stringify(obj)).toBe('{"id":"123n","name":"test"}');
+    });
+
+    it("should stringify arrays containing bigint", () => {
+      const arr = [BigInt(1), BigInt(2), BigInt(3)];
+      expect(stringify(arr)).toBe('["1n","2n","3n"]');
+    });
+
+    it("should stringify nested structures with bigint", () => {
+      const nested = {
+        user: {
+          id: BigInt(999),
+          balance: BigInt(1000000),
+        },
+        items: [BigInt(1), BigInt(2)],
+      };
+      expect(stringify(nested)).toBe(
+        '{"user":{"id":"999n","balance":"1000000n"},"items":["1n","2n"]}'
+      );
+    });
+
+    it("should stringify mixed types with bigint", () => {
+      const mixed = {
+        bigIntValue: BigInt(42),
+        numberValue: 42,
+        stringValue: "42",
+        boolValue: true,
+        nullValue: null,
+      };
+      expect(stringify(mixed)).toBe(
+        '{"bigIntValue":"42n","numberValue":42,"stringValue":"42","boolValue":true,"nullValue":null}'
+      );
+    });
+  });
+
+  describe("objects", () => {
+    it("should stringify empty objects", () => {
+      expect(stringify({})).toBe(JSON.stringify({}));
+    });
+
+    it("should stringify simple objects", () => {
+      const obj = { name: "John", age: 30 };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should stringify nested objects", () => {
+      const nested = {
+        user: {
+          name: "Alice",
+          address: {
+            city: "NYC",
+            zip: "10001",
+          },
+        },
+      };
+      expect(stringify(nested)).toBe(JSON.stringify(nested));
+    });
+
+    it("should stringify objects with various value types", () => {
+      const obj = {
+        str: "text",
+        num: 123,
+        bool: true,
+        nil: null,
+        arr: [1, 2, 3],
+        obj: { nested: "value" },
+      };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+  });
+
+  describe("arrays", () => {
+    it("should stringify empty arrays", () => {
+      expect(stringify([])).toBe(JSON.stringify([]));
+    });
+
+    it("should stringify arrays of primitives", () => {
+      expect(stringify([1, 2, 3])).toBe(JSON.stringify([1, 2, 3]));
+      expect(stringify(["a", "b", "c"])).toBe(JSON.stringify(["a", "b", "c"]));
+      expect(stringify([true, false])).toBe(JSON.stringify([true, false]));
+    });
+
+    it("should stringify arrays of objects", () => {
+      const arr = [
+        { id: 1, name: "first" },
+        { id: 2, name: "second" },
+      ];
+      expect(stringify(arr)).toBe(JSON.stringify(arr));
+    });
+
+    it("should stringify nested arrays", () => {
+      const nested = [
+        [1, 2],
+        [3, 4],
+        [5, 6],
+      ];
+      expect(stringify(nested)).toBe(JSON.stringify(nested));
+    });
+
+    it("should stringify mixed type arrays", () => {
+      const mixed = [1, "two", true, null, { key: "value" }];
+      expect(stringify(mixed)).toBe(JSON.stringify(mixed));
+    });
+  });
+
+  describe("edge cases", () => {
+    it("should handle objects with special characters in keys", () => {
+      const obj = { "key with spaces": "value", "key-with-dashes": "value2" };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle empty strings in objects", () => {
+      const obj = { key: "" };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle Date objects", () => {
+      const date = new Date("2026-01-16T00:00:00.000Z");
+      expect(stringify(date)).toBe(JSON.stringify(date));
+    });
+
+    it("should handle arrays with bigint and other types", () => {
+      const arr = [BigInt(1), "string", 42, true, null, { key: "value" }];
+      expect(stringify(arr)).toBe(
+        '["1n","string",42,true,null,{"key":"value"}]'
+      );
+    });
+
+    it("should handle deeply nested structures with bigint", () => {
+      const deep = {
+        level1: {
+          level2: {
+            level3: {
+              id: BigInt(123),
+              data: [BigInt(1), BigInt(2)],
+            },
+          },
+        },
+      };
+      expect(stringify(deep)).toBe(
+        '{"level1":{"level2":{"level3":{"id":"123n","data":["1n","2n"]}}}}'
+      );
+    });
+
+    it("should handle objects with numeric keys", () => {
+      const obj = { 0: "zero", 1: "one", 2: "two" };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle arrays with undefined and null", () => {
+      const arr = [1, undefined, null, 4];
+      expect(stringify(arr)).toBe(JSON.stringify(arr));
+    });
+
+    it("should handle objects with undefined values", () => {
+      const obj = { a: 1, b: undefined, c: 3 };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle negative bigint values", () => {
+      const obj = {
+        positive: BigInt(100),
+        negative: BigInt(-100),
+        zero: BigInt(0),
+      };
+      expect(stringify(obj)).toBe(
+        '{"positive":"100n","negative":"-100n","zero":"0n"}'
+      );
+    });
+  });
+
+  describe("corner cases", () => {
+    it("should handle empty nested structures", () => {
+      const obj = { empty: {}, emptyArr: [], nested: { inner: {} } };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle special number values in objects", () => {
+      const obj = {
+        infinity: Infinity,
+        negInfinity: -Infinity,
+        nan: NaN,
+        regular: 42,
+      };
+      expect(stringify(obj)).toBe(JSON.stringify(obj));
+    });
+
+    it("should handle bigint in complex nested array", () => {
+      const arr = [
+        [BigInt(1), BigInt(2)],
+        [BigInt(3), BigInt(4)],
+      ];
+      expect(stringify(arr)).toBe('[["1n","2n"],["3n","4n"]]');
+    });
+
+    it("should handle object with only bigint values", () => {
+      const obj = {
+        a: BigInt(1),
+        b: BigInt(2),
+        c: BigInt(3),
+      };
+      expect(stringify(obj)).toBe('{"a":"1n","b":"2n","c":"3n"}');
+    });
+
+    it("should handle array with only bigint values", () => {
+      const arr = [BigInt(10), BigInt(20), BigInt(30)];
+      expect(stringify(arr)).toBe('["10n","20n","30n"]');
+    });
+
+    it("should handle mixed nested structures", () => {
+      const complex = {
+        users: [
+          { id: BigInt(1), name: "Alice", active: true },
+          { id: BigInt(2), name: "Bob", active: false },
+        ],
+        metadata: {
+          count: 2,
+          total: BigInt(1000),
+        },
+      };
+      expect(stringify(complex)).toBe(
+        '{"users":[{"id":"1n","name":"Alice","active":true},{"id":"2n","name":"Bob","active":false}],"metadata":{"count":2,"total":"1000n"}}'
+      );
+    });
+  });
+});