From 308cba7ee024570ec0d6db4317e3485e78c3df0f Mon Sep 17 00:00:00 2001
From: Rui Figueira <rui.figueira@gmail.com>
Date: Mon, 29 Jul 2024 20:22:37 +0100
Subject: [PATCH] test(trace-viewer): use latch to control test execution

---
 tests/spawn-trace-viewer.spec.ts | 21 ++++++++++++---------
 tests/utils.ts                   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/tests/spawn-trace-viewer.spec.ts b/tests/spawn-trace-viewer.spec.ts
index e2c9b9ef3..e6b13ccaf 100644
--- a/tests/spawn-trace-viewer.spec.ts
+++ b/tests/spawn-trace-viewer.spec.ts
@@ -86,25 +86,28 @@ test('should not open trace viewer if test did not run', async ({ activate }) =>
   await expect.poll(() => traceViewerInfo(vscode)).toBeUndefined();
 });
 
-test('should refresh trace viewer while test is running', async ({ activate }) => {
+test('should refresh trace viewer while test is running', async ({ activate, createLatch }) => {
+  const latch = createLatch();
+
   const { vscode, testController } = await activate({
     'playwright.config.js': `module.exports = { testDir: 'tests' }`,
     'tests/test.spec.ts': `
       import { test } from '@playwright/test';
-      test('should pass', async () => await new Promise(r => setTimeout(r, 1000)));
+      test('should pass', async () => ${latch.blockingCode});
     `,
   });
 
   await testController.expandTestItems(/test.spec/);
   selectTestItem(testController.findTestItems(/pass/)[0]);
 
-  await Promise.all([
-    testController.run(),
-    expect.poll(() => traceViewerInfo(vscode)).toMatchObject({
-      type: 'spawn',
-      traceFile: expect.stringMatching(/\.json$/),
-    }),
-  ]);
+  const testRunPromise = testController.run();
+  await expect.poll(() => traceViewerInfo(vscode)).toMatchObject({
+    type: 'spawn',
+    traceFile: expect.stringMatching(/\.json$/),
+  });
+
+  latch.open();
+  await testRunPromise;
 
   await expect.poll(() => traceViewerInfo(vscode)).toMatchObject({
     type: 'spawn',
diff --git a/tests/utils.ts b/tests/utils.ts
index e1b871422..e96c35e7d 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -18,6 +18,8 @@ import { expect as baseExpect, test as baseTest, Browser, chromium, Page } from
 import { Extension } from '../out/extension';
 import { TestController, VSCode, WorkspaceFolder, TestRun, TestItem } from './mock/vscode';
 
+import crypto from 'crypto';
+import fs from 'fs';
 import path from 'path';
 
 type ActivateResult = {
@@ -26,11 +28,18 @@ type ActivateResult = {
   workspaceFolder: WorkspaceFolder;
 };
 
+type Latch = {
+  blockingCode: string;
+  open: () => void;
+  close: () => void;
+};
+
 type TestFixtures = {
   vscode: VSCode,
   activate: (files: { [key: string]: string }, options?: { rootDir?: string, workspaceFolders?: [string, any][], env?: Record<string, any> }) => Promise<ActivateResult>;
   showTrace: boolean;
   envRemoteName?: string;
+  createLatch: () => Latch;
 };
 
 export type WorkerOptions = {
@@ -160,6 +169,18 @@ export const test = baseTest.extend<TestFixtures, WorkerOptions>({
     for (const vscode of instances)
       vscode.dispose();
   },
+
+  // Copied from https://github.com/microsoft/playwright/blob/7e7319da7d84de6648900e27e6d844bec9071222/tests/playwright-test/ui-mode-fixtures.ts#L132
+  createLatch: async ({}, use, testInfo) => {
+    await use(() => {
+      const latchFile = path.join(testInfo.project.outputDir, createGuid() + '.latch');
+      return {
+        blockingCode: `await ((${waitForLatch})(${JSON.stringify(latchFile)}))`,
+        open: () => fs.writeFileSync(latchFile, 'ok'),
+        close: () => fs.unlinkSync(latchFile),
+      };
+    });
+  },
 });
 
 export async function connectToSharedBrowser(vscode: VSCode) {
@@ -234,3 +255,13 @@ export async function singleWebViewByPanelType(vscode: VSCode, viewType: string)
 export function traceViewerInfo(vscode: VSCode): { type: 'spawn' | 'embedded', serverUrlPrefix?: string, testConfigFile: string } | undefined {
   return vscode.extensions[0].traceViewerInfoForTest();
 }
+
+async function waitForLatch(latchFile: string) {
+  const fs = require('fs');
+  while (!fs.existsSync(latchFile))
+    await new Promise(f => setTimeout(f, 250));
+}
+
+function createGuid(): string {
+  return crypto.randomBytes(16).toString('hex');
+}