[vitest-pool-workers] vitest run --coverage failed with 0.13.1 and @vitest/coverage-istanbul@4.1.0

[nus25]

What versions & operating system are you using?

System:
OS: Linux 6.17 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
CPU: (10) x64 VirtualApple @ 2.50GHz
Memory: 3.34 GB / 7.81 GB
Container: Yes
Shell: 5.2.15 - /bin/bash
Binaries:
Node: 22.16.0 - /usr/local/bin/node
Yarn: 1.22.22 - /usr/local/bin/yarn
npm: 10.9.2 - /usr/local/bin/npm
pnpm: 10.11.0 - /usr/local/share/npm-global/bin/pnpm
npmPackages:
@cloudflare/vitest-pool-workers: ^0.13.1 => 0.13.1
wrangler: ^4.74.0 => 4.74.0

Please provide a link to a minimal reproduction

https://github.com/nus25/reproduction-istanbul-error

Describe the Bug

I’m encountering an unhandled error TypeError: template is not a function when running vitest run --coverage in any project that uses vitest-pool-workers@0.13.1 with vitest@4.1.0 and @vitest/coverage-istanbul@4.1.0.

If I downgrade istanbul to 4.0.18, the command runs successfully, although it prints a peer dependency warning.

Please provide any relevant error logs

node ➜ /workspaces/workers/reproduction-istanbul-error (main) $ pnpm vitest run --coverage

RUN v4.1.0 /workspaces/workers/reproduction-istanbul-error

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Error ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
TypeError: template is not a function
❯ requireVisitor node_modules/.pnpm/@vitest+coverage-istanbul@4.1.0_vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0__/node_modules/@vitest/coverage-istanbul/dist/provider.js:1024:40
1022| LogicalExpression: entries(coverLogicalExpression)
1023| };
1024| const globalTemplateAlteredFunction = template(`
| ^
1025| var Function = (function(){}).constructor;
1026| var global = (new Function(GLOBAL_COVERAGE_SCOPE))();
❯ requireInstrumenter node_modules/.pnpm/@vitest+coverage-istanbul@4.1.0_vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0__/node_modules/@vitest/coverage-istanbul/dist/provider.js:1325:25
❯ requireSrc$1 node_modules/.pnpm/@vitest+coverage-istanbul@4.1.0_vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0__/node_modules/@vitest/coverage-istanbul/dist/provider.js:1495:23
❯ node_modules/.pnpm/@vitest+coverage-istanbul@4.1.0_vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0__/node_modules/@vitest/coverage-istanbul/dist/provider.js:1518:18
❯ VitestModuleEvaluator.runInlinedModule node_modules/.pnpm/vitest@4.1.0@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0_/node_modules/vitest/dist/module-evaluator.js:206:4
❯ ServerModuleRunner.directRequest node_modules/.pnpm/vite@7.3.1_@types+node@25.5.0/node_modules/vite/dist/node/module-runner.js:1146:59
❯ ServerModuleRunner.cachedRequest node_modules/.pnpm/vite@7.3.1_@types+node@25.5.0/node_modules/vite/dist/node/module-runner.js:1053:73
❯ Object.getProvider node_modules/.pnpm/@vitest+coverage-istanbul@4.1.0_vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0__/node_modules/@vitest/coverage-istanbul/dist/index.js:31:40
❯ Vitest.initCoverageProvider node_modules/.pnpm/vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0_/node_modules/vitest/dist/chunks/cli-api.DuT9iuvY.js:13181:28
❯ node_modules/.pnpm/vitest@4.1.0_@types+node@25.5.0_vite@7.3.1_@types+node@25.5.0_/node_modules/vitest/dist/chunks/cli-api.DuT9iuvY.js:13302:6

Test Files 0 passed (0)
Tests 0 passed (0)
Start at
Duration 0ms

[petebacondarwin]

Is this fixed upstream by vitest-dev/vitest#9939, which just got merged?

[nus25]

Is this fixed upstream by vitest-dev/vitest#9939, which just got merged?

I tried the fixed packages mentioned in the following PR comment and confirmed that pnpm vitest run --coverage ran successfully.
vitest-dev/vitest#9939 (comment)

This issue can be closed when next version of "@vitest/coverage-istanbul" is released.

Thank you!

[nus25]

I also confirmed that this issue is fixed with the newly released "@vitest/coverage-istanbul": "^4.1.1".

node ➜ /workspaces/workers/reproduction-istanbul-error (main) $ pnpm list
Legend: production dependency, optional only, dev only

reproduction-istanbul-error@0.0.0 /workspaces/workers/reproduction-istanbul-error (PRIVATE)

devDependencies:
@cloudflare/vitest-pool-workers 0.13.3
@types/node 25.5.0
@vitest/coverage-istanbul 4.1.1
typescript 5.9.3
vitest 4.1.1
wrangler 4.74.0
node ➜ /workspaces/workers/reproduction-istanbul-error (main) $ pnpm vitest run --coverage 

 RUN  v4.1.1 /workspaces/workers/reproduction-istanbul-error
      Coverage enabled with istanbul

[vpw:debug] Adding `enable_nodejs_tty_module` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:debug] Adding `enable_nodejs_fs_module` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:debug] Adding `enable_nodejs_http_modules` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:debug] Adding `enable_nodejs_perf_hooks_module` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:debug] Adding `enable_nodejs_v8_module` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:debug] Adding `enable_nodejs_process_v2` compatibility flag during tests as this feature is needed to support the Vitest runner.
[vpw:info] Starting runtime for ...
 ✓  Workers Tests  test/index.spec.ts (2 tests) 29ms
   ✓ Hello World worker (2)
     ✓ responds with Hello World! (unit style) 16ms
     ✓ responds with Hello World! (integration style) 8ms

 Test Files  1 passed (1)
      Tests  2 passed (2)
   Start at  10:26:38
   Duration  1.01s (transform 119ms, setup 0ms, import 144ms, tests 29ms, environment 0ms)

 % Coverage report from istanbul
----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |                   
 index.ts |     100 |      100 |     100 |     100 |                   
----------|---------|----------|---------|---------|-------------------

[petebacondarwin]

Great! Closing this then. Thanks for reporting.