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mikewheeleer merged 1 commit into from
Jul 15, 2026
Merged

test: extend apiClient error and 204 handling tests #281

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271 changes: 151 additions & 120 deletions src/lib/__tests__/apiClient.test.ts
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Original file line number Diff line number Diff line change
@@ -1,120 +1,151 @@
import { apiFetch, registerAuthErrorHandler } from "../apiClient";

function mockResponse(status: number, body: string, contentType = "application/json") {
global.fetch = jest.fn().mockResolvedValue({
status,
ok: status >= 200 && status < 300,
text: () => Promise.resolve(body),
headers: { get: () => contentType },
} as unknown as Response);
}

afterEach(() => jest.restoreAllMocks());

describe("apiFetch", () => {
it("returns parsed JSON on success", async () => {
mockResponse(200, JSON.stringify({ id: 1 }));
await expect(apiFetch("/test")).resolves.toEqual({ id: 1 });
});

it("returns undefined for 204", async () => {
global.fetch = jest.fn().mockResolvedValue({
status: 204,
ok: true,
text: () => Promise.resolve(""),
} as unknown as Response);
await expect(apiFetch("/test")).resolves.toBeUndefined();
});

it("throws with message from JSON error body", async () => {
mockResponse(400, JSON.stringify({ error: "bad_request", message: "Invalid input" }));
await expect(apiFetch("/test")).rejects.toThrow("Invalid input");
});

it("throws HTTP status when error body is empty", async () => {
mockResponse(500, "");
await expect(apiFetch("/test")).rejects.toThrow("HTTP 500");
});

it("throws HTTP status when error body is non-JSON", async () => {
mockResponse(503, "Service Unavailable", "text/plain");
await expect(apiFetch("/test")).rejects.toThrow("HTTP 503");
});

it("throws on non-JSON success body", async () => {
mockResponse(200, "not json");
await expect(apiFetch("/test")).rejects.toThrow("Invalid JSON response");
});

it("attaches status to the thrown error for non-auth failures", async () => {
mockResponse(400, JSON.stringify({ error: "bad_request", message: "Invalid input" }));
const err = await apiFetch("/test").catch((e: unknown) => e) as Error & { status: number };
expect(err).toBeInstanceOf(Error);
expect(err.status).toBe(400);
});
});

describe("registerAuthErrorHandler", () => {
it("calls the handler with 401 when the server returns 401", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).toHaveBeenCalledTimes(1);
expect(handler).toHaveBeenCalledWith(401);
unregister();
});

it("calls the handler with 403 when the server returns 403", async () => {
mockResponse(403, JSON.stringify({ error: "forbidden", message: "Access denied" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).toHaveBeenCalledTimes(1);
expect(handler).toHaveBeenCalledWith(403);
unregister();
});

it("does NOT call the handler for non-auth errors", async () => {
mockResponse(500, "");
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/test").catch(() => {/* expected rejection */});

expect(handler).not.toHaveBeenCalled();
unregister();
});

it("does NOT call the handler after unregistering", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Gone" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);
unregister(); // remove before the request

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).not.toHaveBeenCalled();
});

it("still throws the error even when the handler is registered", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const unregister = registerAuthErrorHandler(jest.fn());

await expect(apiFetch("/secure")).rejects.toThrow("Not authenticated");
unregister();
});

it("attaches status 401 to the thrown error", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const unregister = registerAuthErrorHandler(jest.fn());

const err = await apiFetch("/secure").catch((e: unknown) => e) as Error & { status: number };
expect(err.status).toBe(401);
unregister();
});
});
import { apiFetch, registerAuthErrorHandler } from "../apiClient";

function mockResponse(status: number, body: string, contentType = "application/json") {
global.fetch = jest.fn().mockResolvedValue({
status,
ok: status >= 200 && status < 300,
text: () => Promise.resolve(body),
headers: { get: () => contentType },
} as unknown as Response);
}

afterEach(() => jest.restoreAllMocks());

describe("apiFetch", () => {
it("returns parsed JSON on success", async () => {
mockResponse(200, JSON.stringify({ id: 1 }));
await expect(apiFetch("/test")).resolves.toEqual({ id: 1 });
});

it("returns undefined for 204", async () => {
global.fetch = jest.fn().mockResolvedValue({
status: 204,
ok: true,
text: () => Promise.resolve(""),
} as unknown as Response);
await expect(apiFetch("/test")).resolves.toBeUndefined();
});

it("throws with message from JSON error body", async () => {
mockResponse(400, JSON.stringify({ error: "bad_request", message: "Invalid input" }));
await expect(apiFetch("/test")).rejects.toThrow("Invalid input");
});

it("throws HTTP status when error body is empty", async () => {
mockResponse(500, "");
await expect(apiFetch("/test")).rejects.toThrow("HTTP 500");
});

it("throws HTTP status when error body is non-JSON", async () => {
mockResponse(503, "Service Unavailable", "text/plain");
await expect(apiFetch("/test")).rejects.toThrow("HTTP 503");
});

it("throws on non-JSON success body", async () => {
mockResponse(200, "not json");
await expect(apiFetch("/test")).rejects.toThrow("Invalid JSON response");
});

it("attaches status to the thrown error for non-auth failures", async () => {
mockResponse(400, JSON.stringify({ error: "bad_request", message: "Invalid input" }));
const err = await apiFetch("/test").catch((e: unknown) => e) as Error & { status: number };
expect(err).toBeInstanceOf(Error);
expect(err.status).toBe(400);
});
});

describe("registerAuthErrorHandler", () => {
it("calls the handler with 401 when the server returns 401", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).toHaveBeenCalledTimes(1);
expect(handler).toHaveBeenCalledWith(401);
unregister();
});

it("calls the handler with 403 when the server returns 403", async () => {
mockResponse(403, JSON.stringify({ error: "forbidden", message: "Access denied" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).toHaveBeenCalledTimes(1);
expect(handler).toHaveBeenCalledWith(403);
unregister();
});

it("does NOT call the handler for non-auth errors", async () => {
mockResponse(500, "");
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);

await apiFetch("/test").catch(() => {/* expected rejection */});

expect(handler).not.toHaveBeenCalled();
unregister();
});

it("does NOT call the handler after unregistering", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Gone" }));
const handler = jest.fn();
const unregister = registerAuthErrorHandler(handler);
unregister(); // remove before the request

await apiFetch("/secure").catch(() => {/* expected rejection */});

expect(handler).not.toHaveBeenCalled();
});

it("still throws the error even when the handler is registered", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const unregister = registerAuthErrorHandler(jest.fn());

await expect(apiFetch("/secure")).rejects.toThrow("Not authenticated");
unregister();
});

it("attaches status 401 to the thrown error", async () => {
mockResponse(401, JSON.stringify({ error: "unauthorized", message: "Not authenticated" }));
const unregister = registerAuthErrorHandler(jest.fn());

const err = await apiFetch("/secure").catch((e: unknown) => e) as Error & { status: number };
expect(err.status).toBe(401);
unregister();
});

it("retries idempotent GET requests on 5xx with backoff", async () => {
jest.useFakeTimers();
const fetchMock = jest
.fn()
.mockResolvedValueOnce({
status: 503,
ok: false,
text: () => Promise.resolve(""),
} as unknown as Response)
.mockResolvedValueOnce({
status: 200,
ok: true,
text: () => Promise.resolve(JSON.stringify({ ok: true })),
} as unknown as Response);
global.fetch = fetchMock as unknown as typeof global.fetch;

const promise = apiFetch("/retry-me", {}, { retry: { maxAttempts: 2, baseDelayMs: 50 } });
await jest.advanceTimersByTimeAsync(50);
await expect(promise).resolves.toEqual({ ok: true });
expect(fetchMock).toHaveBeenCalledTimes(2);
jest.useRealTimers();
});

it("does not retry non-GET methods", async () => {
mockResponse(503, "");
await expect(
apiFetch("/retry-me", { method: "POST", body: "{}" }, { retry: { maxAttempts: 3 } }),
).rejects.toThrow("HTTP 503");
expect(global.fetch).toHaveBeenCalledTimes(1);
});
});