deflake test

src/async.test.ts

@@ -1,6 +1,7 @@
 import { jest } from "@jest/globals";
 import { times } from "./array.js";
 import { delay, mapConcurrent, TimeoutError, withTimeout } from "./async.js";
+import { isArm } from "./platform.js";
 import { DayMs, HourMs } from "./units.js";
 
 describe("async", () => {
@@ -395,7 +396,8 @@ describe("async", () => {
           maxConcurrency,
         });
         expect(results).toEqual(times(10, (i) => i * 2));
-        expect(Date.now() - start).toBeLessThan(200); // Should complete concurrently
+        // This should complete in ~100ms, but GHA runners are slow -- the alpine ARM runner took 243ms (!!)
+        expect(Date.now() - start).toBeLessThan(isArm ? 250 : 200);
       });
 
       it("should maintain proper order even with varying execution times", async () => {

src/platform.ts

@@ -1,9 +1,9 @@
 // src/platform.ts
 
-import { platform } from "node:os";
+import { arch, platform } from "node:process";
 
-const p = platform();
+export const isLinux = platform === "linux";
+export const isWindows = platform === "win32";
+export const isMacOS = platform === "darwin";
 
-export const isLinux = p === "linux";
-export const isWindows = p === "win32";
-export const isMacOS = p === "darwin";
+export const isArm = isLinux && arch.startsWith("arm");