diff --git a/src/lib/__tests__/github/handleRateLimit.test.ts b/src/lib/__tests__/github/handleRateLimit.test.ts
new file mode 100644
index 00000000..b8b5c6ef
--- /dev/null
+++ b/src/lib/__tests__/github/handleRateLimit.test.ts
@@ -0,0 +1,63 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { handleRateLimit } from "../../github";
+import { RateLimitError } from "../../types";
+
+describe("handleRateLimit", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2024-01-01T00:00:00Z")); // 1704067200 in seconds
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("throws RateLimitError with valid X-RateLimit-Reset header", () => {
+    const validTimestamp = 1704070800; // 1 hour later
+    const res = {
+      headers: new Headers({ "X-RateLimit-Reset": validTimestamp.toString() })
+    } as unknown as Response;
+
+    try {
+      handleRateLimit(res);
+      expect.fail("Should throw RateLimitError");
+    } catch (e) {
+      expect(e).toBeInstanceOf(RateLimitError);
+      expect((e as RateLimitError).resetAt.getTime()).toBe(validTimestamp * 1000);
+    }
+  });
+
+  it("throws RateLimitError with fallback timestamp when header is missing", () => {
+    const res = {
+      headers: new Headers() // Empty headers
+    } as unknown as Response;
+
+    const currentSeconds = Math.floor(Date.now() / 1000);
+    const expectedFallback = currentSeconds + 3600;
+
+    try {
+      handleRateLimit(res);
+      expect.fail("Should throw RateLimitError");
+    } catch (e) {
+      expect(e).toBeInstanceOf(RateLimitError);
+      expect((e as RateLimitError).resetAt.getTime()).toBe(expectedFallback * 1000);
+    }
+  });
+
+  it("throws RateLimitError with fallback timestamp when header is invalid", () => {
+    const res = {
+      headers: new Headers({ "X-RateLimit-Reset": "invalid_timestamp" })
+    } as unknown as Response;
+
+    const currentSeconds = Math.floor(Date.now() / 1000);
+    const expectedFallback = currentSeconds + 3600;
+
+    try {
+      handleRateLimit(res);
+      expect.fail("Should throw RateLimitError");
+    } catch (e) {
+      expect(e).toBeInstanceOf(RateLimitError);
+      expect((e as RateLimitError).resetAt.getTime()).toBe(expectedFallback * 1000);
+    }
+  });
+});