fix(desktop): update from the splash only after the user clicks (#3280)

fluxer_desktop/src/main/DesktopUpdateGate.test.mjs

@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import assert from 'node:assert/strict';
+import {describe, test} from 'node:test';
+import {installElectronStub} from './LocalAppTestSupport.test.mjs';
+
+installElectronStub();
+
+const {
+	armDesktopUpdate,
+	checkDesktopUpdateNow,
+	getDesktopUpdateState,
+	observeDesktopUpdateState,
+	publishDesktopUpdateCheck,
+	startDesktopUpdate,
+} = await import('@electron/main/DesktopUpdateGate');
+
+function deferred() {
+	let resolve;
+	const promise = new Promise((resolvePromise) => {
+		resolve = resolvePromise;
+	});
+	return {promise, resolve};
+}
+
+describe('DesktopUpdateGate', () => {
+	test('nothing is available and nothing starts before the bootstrap arms the gate', async () => {
+		assert.deepEqual(getDesktopUpdateState(), {available: false});
+		assert.deepEqual(await checkDesktopUpdateNow(), {available: false});
+		assert.equal(startDesktopUpdate(), false);
+	});
+
+	test('a check publishes the update and one click runs it exactly once', async () => {
+		const states = [];
+		const stop = observeDesktopUpdateState((state) => states.push(state.available));
+		const running = deferred();
+		let starts = 0;
+		armDesktopUpdate({
+			check: async () => ({shellNewer: false, modulesChanged: true}),
+			start: async () => {
+				starts += 1;
+				await running.promise;
+				publishDesktopUpdateCheck({shellNewer: false, modulesChanged: false});
+			},
+		});
+
+		assert.deepEqual(await checkDesktopUpdateNow(), {available: true});
+		assert.equal(startDesktopUpdate(), true);
+		assert.equal(startDesktopUpdate(), false, 'a second click while the update runs is a no-op');
+		assert.deepEqual(getDesktopUpdateState(), {available: false}, 'the affordance hides the moment it is clicked');
+		assert.deepEqual(await checkDesktopUpdateNow(), {available: false}, 'a poll during the update changes nothing');
+
+		running.resolve();
+		await new Promise((resolve) => setImmediate(resolve));
+
+		assert.equal(starts, 1);
+		assert.deepEqual(getDesktopUpdateState(), {available: false});
+		assert.deepEqual(states, [true, false]);
+		stop();
+	});
+
+	test('a shell update that could not finish stays available for the next click', async () => {
+		armDesktopUpdate({
+			check: async () => ({shellNewer: true, modulesChanged: false}),
+			start: async () => {
+				publishDesktopUpdateCheck({shellNewer: true, modulesChanged: false});
+			},
+		});
+		await checkDesktopUpdateNow();
+
+		assert.equal(startDesktopUpdate(), true);
+		await new Promise((resolve) => setImmediate(resolve));
+
+		assert.deepEqual(getDesktopUpdateState(), {available: true});
+		assert.equal(startDesktopUpdate(), true);
+	});
+});