apply sequencer to browser tests

.gitignore

@@ -17,6 +17,7 @@ ltex*
 bench/test/*/*/
 **/benchmark/bench.json
 **/browser/browser.json
+**/browser/browser-shard.json
 cypress/videos
 cypress/downloads
 cypress/screenshots

packages/vitest/src/node/pools/browser.ts

@@ -1,7 +1,7 @@
 import { createDefer } from '@vitest/utils'
 import { relative } from 'pathe'
 import type { Vitest } from '../core'
-import type { ProcessPool } from '../pool'
+import type { ProcessPool, WorkspaceSpec } from '../pool'
 import type { WorkspaceProject } from '../workspace'
 import type { BrowserProvider } from '../../types/browser'
 
@@ -27,6 +27,9 @@ export function createBrowserPool(ctx: Vitest): ProcessPool {
     }
   }
 
+  const Sequencer = ctx.config.sequence.sequencer
+  const sequencer = new Sequencer(ctx)
+
   const runTests = async (project: WorkspaceProject, files: string[]) => {
     ctx.state.clearFiles(project, files)
 
@@ -39,7 +42,13 @@ export function createBrowserPool(ctx: Vitest): ProcessPool {
     providers.add(provider)
 
     const origin = `http://${ctx.config.browser.api?.host || 'localhost'}:${project.browser!.config.server.port}`
-    const paths = files.map(file => relative(project.config.root, file))
+
+    let specs: Array<WorkspaceSpec> = files.map(file => [project, file])
+    if (ctx.config.shard)
+      specs = await sequencer.shard(specs)
+    specs = await sequencer.sort(specs)
+
+    const paths = specs.map(([,file]) => relative(project.config.root, file))
 
     if (project.config.browser.isolate) {
       for (const path of paths) {

test/browser/specs/shard.test.mjs

@@ -0,0 +1,22 @@
+import assert from 'node:assert'
+import { readFile } from 'node:fs/promises'
+import test from 'node:test'
+import { execa } from 'execa'
+
+const browser = process.env.BROWSER || (process.env.PROVIDER === 'playwright' ? 'chromium' : 'chrome')
+
+await execa('npx', ['vitest', '--run', '--shard=1/2', `--browser.name=${browser}`, '--browser.headless', '--outputFile=./browser-shard.json'], {
+  env: {
+    ...process.env,
+    CI: 'true',
+    NO_COLOR: 'true',
+  },
+  reject: false,
+})
+
+const browserResult = await readFile('./browser-shard.json', 'utf-8')
+const browserResultJson = JSON.parse(browserResult)
+
+await test('shard option runs portion of tests', async () => {
+  assert.strictEqual(browserResultJson.testResults.length, 4)
+})