fix(updates): let a release candidate's manual check see newer RCs

electron/update-checker.test.ts

@@ -154,6 +154,68 @@ describe("checkLatestRelease", () => {
 		);
 	});
 
+	// releases/latest never returns a prerelease, so an RC read it and never saw the next RC (#1447).
+	describe("on a release candidate", () => {
+		const release = (tag: string, prerelease: boolean) => ({
+			tag_name: tag,
+			html_url: `https://github.com/getopenscreen/openscreen/releases/tag/${tag}`,
+			draft: false,
+			prerelease,
+		});
+		const releases = [
+			release("v2.1.2", false),
+			release("v2.2.0-rc.2", true),
+			release("v2.2.0-rc.1", true),
+		];
+
+		it("offers the next RC from the release list", async () => {
+			const fetchLatest = vi.fn().mockResolvedValue(releaseResponse(releases));
+
+			await expect(
+				checkLatestRelease({ currentVersion: "2.2.0-rc.1", fetchLatest }),
+			).resolves.toEqual({
+				kind: "available",
+				currentVersion: "2.2.0-rc.1",
+				latestVersion: "2.2.0-rc.2",
+				releaseUrl: "https://github.com/getopenscreen/openscreen/releases/tag/v2.2.0-rc.2",
+			});
+			expect(fetchLatest).toHaveBeenCalledWith(
+				"https://api.github.com/repos/getopenscreen/openscreen/releases?per_page=30",
+				expect.anything(),
+			);
+		});
+
+		it("offers the stable release that supersedes it", async () => {
+			const fetchLatest = vi
+				.fn()
+				.mockResolvedValue(releaseResponse([release("v2.2.0", false), ...releases]));
+
+			await expect(
+				checkLatestRelease({ currentVersion: "2.2.0-rc.2", fetchLatest }),
+			).resolves.toMatchObject({ kind: "available", latestVersion: "2.2.0" });
+		});
+
+		it("reports current on the newest RC", async () => {
+			const fetchLatest = vi.fn().mockResolvedValue(releaseResponse(releases));
+
+			await expect(
+				checkLatestRelease({ currentVersion: "2.2.0-rc.2", fetchLatest }),
+			).resolves.toMatchObject({ kind: "current", latestVersion: "2.2.0-rc.2" });
+		});
+
+		it.each([
+			[[]],
+			[release("v2.2.0-rc.2", true)],
+			[[{ ...release("v9.9.9", true), draft: true }]],
+		])("rejects an empty, non-list or draft response: %o", async (payload) => {
+			const fetchLatest = vi.fn().mockResolvedValue(releaseResponse(payload));
+
+			await expect(
+				checkLatestRelease({ currentVersion: "2.2.0-rc.1", fetchLatest }),
+			).rejects.toThrow("invalid GitHub release response");
+		});
+	});
+
 	it("rejects unsuccessful or malformed GitHub responses", async () => {
 		const unavailable = vi.fn().mockResolvedValue(releaseResponse({}, 503));
 		await expect(

electron/update-checker.ts

@@ -1,4 +1,5 @@
 const LATEST_RELEASE_API = "https://api.github.com/repos/getopenscreen/openscreen/releases/latest";
+const RELEASES_API = "https://api.github.com/repos/getopenscreen/openscreen/releases?per_page=30";
 const OFFICIAL_RELEASE_PREFIX = "/getopenscreen/openscreen/releases/tag/";
 
 interface ReleaseResponse {
@@ -118,12 +119,47 @@ export type UpdateCheckResult =
 			latestVersion: string;
 	  };
 
+interface Release {
+	tag_name: string;
+	html_url: string;
+}
+
+function asRelease(payload: unknown, allowPrerelease: boolean): Release {
+	const fields = payload as Record<string, unknown>;
+	if (
+		typeof payload !== "object" ||
+		payload === null ||
+		typeof fields.tag_name !== "string" ||
+		typeof fields.html_url !== "string" ||
+		fields.draft !== false ||
+		(allowPrerelease ? typeof fields.prerelease !== "boolean" : fields.prerelease !== false)
+	) {
+		throw new Error("invalid GitHub release response");
+	}
+	return payload as Release;
+}
+
+function newestRelease(payload: unknown): Release {
+	if (!Array.isArray(payload) || payload.length === 0) {
+		throw new Error("invalid GitHub release response");
+	}
+	return payload
+		.map((entry) => asRelease(entry, true))
+		.reduce((newest, release) =>
+			compareVersions(release.tag_name, newest.tag_name) > 0 ? release : newest,
+		);
+}
+
 export async function checkLatestRelease(options: {
 	currentVersion: string;
 	fetchLatest: FetchLatestRelease;
 	signal?: AbortSignal;
 }): Promise<UpdateCheckResult> {
-	const response = await options.fetchLatest(LATEST_RELEASE_API, {
+	const current = parseVersion(options.currentVersion);
+	// releases/latest only ever resolves to a stable release, so an RC would never be offered the
+	// next RC (#1447). An RC tester opted into prereleases: compare against them too.
+	const onPrerelease = current.prerelease.length > 0;
+	const response = await options.fetchLatest(onPrerelease ? RELEASES_API : LATEST_RELEASE_API, {
 		headers: {
 			Accept: "application/vnd.github+json",
 			"X-GitHub-Api-Version": "2022-11-28",
@@ -133,18 +169,7 @@ export async function checkLatestRelease(options: {
 	if (!response.ok) throw new Error(`GitHub release check failed (${response.status})`);
 
 	const payload = await response.json();
-	if (
-		typeof payload !== "object" ||
-		payload === null ||
-		typeof (payload as Record<string, unknown>).tag_name !== "string" ||
-		typeof (payload as Record<string, unknown>).html_url !== "string" ||
-		(payload as Record<string, unknown>).draft !== false ||
-		(payload as Record<string, unknown>).prerelease !== false
-	) {
-		throw new Error("invalid GitHub release response");
-	}
-	const release = payload as { tag_name: string; html_url: string };
-	const current = parseVersion(options.currentVersion);
+	const release = onPrerelease ? newestRelease(payload) : asRelease(payload, false);
 	const latest = parseVersion(release.tag_name);
 	const comparison = compareVersions(latest.normalized, current.normalized);
 	if (comparison <= 0) {