From 530d26684b702547176e457af3be349a07c0f5bc Mon Sep 17 00:00:00 2001
From: David Evans <davidje13@users.noreply.github.com>
Date: Thu, 25 Jul 2024 20:38:09 +0100
Subject: [PATCH] Avoid flakes in download test

---
 e2e/helpers/downloads.ts      | 16 +++++++++++-----
 e2e/pages/RetroArchiveList.ts |  2 +-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/e2e/helpers/downloads.ts b/e2e/helpers/downloads.ts
index ce1f8e3..f7660e8 100644
--- a/e2e/helpers/downloads.ts
+++ b/e2e/helpers/downloads.ts
@@ -1,6 +1,6 @@
 import { fileURLToPath } from 'node:url';
 import { join, dirname } from 'node:path';
-import { readFile, mkdir, rm } from 'node:fs/promises';
+import { readFile, mkdir, rm, stat } from 'node:fs/promises';
 
 export const downloadDir = join(
   dirname(fileURLToPath(import.meta.url)),
@@ -11,8 +11,11 @@ export const downloadDir = join(
 await rm(downloadDir, { recursive: true, force: true });
 await mkdir(downloadDir, { recursive: true });
 
+const sleep = (ms: number) => new Promise((res) => setTimeout(res, ms));
+
 export async function waitForFile(
   name: string,
+  minimumSize: number,
   timeout: number,
 ): Promise<string> {
   const fileName = join(downloadDir, name);
@@ -20,10 +23,13 @@ export async function waitForFile(
 
   do {
     try {
-      return await readFile(fileName, { encoding: 'utf-8' });
-    } catch (e) {
-      await new Promise((res) => setTimeout(res, 100));
-    }
+      const { size } = await stat(fileName);
+      if (size >= minimumSize) { // wait until file has some content
+        await sleep(10); // wait a little longer to avoid partial file reads if we get unlucky with the timing
+        return await readFile(fileName, { encoding: 'utf-8' });
+      }
+    } catch {}
+    await sleep(100);
   } while (Date.now() < exp);
 
   throw new Error(`Failed to download file ${name} within ${timeout}ms`);
diff --git a/e2e/pages/RetroArchiveList.ts b/e2e/pages/RetroArchiveList.ts
index 47f0716..474d703 100644
--- a/e2e/pages/RetroArchiveList.ts
+++ b/e2e/pages/RetroArchiveList.ts
@@ -20,7 +20,7 @@ export class RetroArchiveList extends Page {
 
   public async clickExportJson(): Promise<string> {
     await this.click(By.linkText('Export as JSON'));
-    return waitForFile(`${this.slug}-export.json`, this.explicitWaitTimeout);
+    return waitForFile(`${this.slug}-export.json`, 10, this.explicitWaitTimeout);
   }
 
   public async getArchiveLabels(): Promise<string[]> {