Fix handling of a signal that is already aborted before the request begins (#663)

* fix: throw early if signal is aborted before request is triggered

* fix: abort if the original signal also aborted early

* fix: linter issues

* fix: pass abort reason to early abort

* fix: check if server receives request after abort

* fix: lint issues

Author: kadhirr

source/core/Ky.ts

@@ -163,10 +163,13 @@ export class Ky {
 		if (supportsAbortController) {
 			this.abortController = new globalThis.AbortController();
 			const originalSignal = this._options.signal ?? (this._input as Request).signal;
+			if (originalSignal?.aborted) {
+				this.abortController.abort(originalSignal?.reason);
+			}
+
 			originalSignal?.addEventListener('abort', () => {
 				this.abortController!.abort(originalSignal.reason);
 			});
-
 			this._options.signal = this.abortController.signal;
 		}
 

test/main.ts

@@ -713,6 +713,26 @@ test('throws DOMException/Error with name AbortError when aborted by user', asyn
 	t.is(error.name, 'AbortError', `Expected AbortError, got ${error.name}`);
 });
 
+test('throws AbortError when signal was aborted before request', async t => {
+	const server = await createHttpTestServer();
+	let requestCount = 0;
+	server.get('/', () => {
+		requestCount += 1;
+	});
+
+	const abortController = new AbortController();
+	const {signal} = abortController;
+	const request = new Request(server.url, {signal});
+	abortController.abort();
+	const response = ky(request);
+
+	const error = (await t.throwsAsync(response))!;
+
+	t.true(['DOMException', 'Error'].includes(error.constructor.name), `Expected DOMException or Error, got ${error.constructor.name}`);
+	t.is(error.name, 'AbortError', `Expected AbortError, got ${error.name}`);
+	t.is(requestCount, 0, 'Request count is more than 0, server received request.');
+});
+
 test('throws AbortError when aborted via Request', async t => {
 	const server = await createHttpTestServer();
 	// eslint-disable-next-line @typescript-eslint/no-empty-function