diff --git a/src/lib/utils/api.test.ts b/src/lib/utils/api.test.ts
new file mode 100644
index 000000000..581e52d3f
--- /dev/null
+++ b/src/lib/utils/api.test.ts
@@ -0,0 +1,22 @@
+import { test, expect } from "vitest";
+import { isErrorCode, isRedirectCode } from "./api";
+
+test("isErrorCode", () => {
+  expect(isErrorCode(200)).toBe(false);
+  expect(isErrorCode(204)).toBe(false);
+  expect(isErrorCode(301)).toBe(false);
+  expect(isErrorCode(307)).toBe(false);
+  expect(isErrorCode(400)).toBe(true);
+  expect(isErrorCode(404)).toBe(true);
+  expect(isErrorCode(500)).toBe(true);
+});
+
+test("isRedirectCode", () => {
+  expect(isRedirectCode(200)).toBe(false);
+  expect(isRedirectCode(204)).toBe(false);
+  expect(isRedirectCode(301)).toBe(true);
+  expect(isRedirectCode(307)).toBe(true);
+  expect(isRedirectCode(400)).toBe(false);
+  expect(isRedirectCode(404)).toBe(false);
+  expect(isRedirectCode(500)).toBe(false);
+});