Vitest code coverage not properly reported

[json-derulo]

Command

test

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

I am trying out the new experimental vitest builder, which works great for me in general! I just found an issue with the coverage reporting. After installing @vitest/coverage-v8 and running ng test --code-coverage with the vitest builder, the coverage is not properly reported. The displayed coverage table appears empty:

The XML, JSON and HTML reports located in dist/test-out/**/coverage are also empty. As there is actually something tested in app.ts, I would have expected something to appear in the coverage report.

Minimal Reproduction

1. Generate a fresh project with npx@angular/cli@next new and switch to the unit-test builder, or check out the code from the reproduction repo: https://github.com/json-derulo/ng20-vitest
2. Run ng test --code-coverage
3. Take a look at the console output

Exception or Error

No exception or error visible, but the coverage is not reported

Your Environment

Angular CLI: 20.0.0-rc.2
Node: 22.15.1
Package Manager: pnpm 9.15.6
OS: darwin x64

Angular: 20.0.0-rc.1
... common, compiler, compiler-cli, core, forms
... platform-browser, router

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.2000.0-rc.2 (cli-only)
@angular-devkit/core         20.0.0-rc.2 (cli-only)
@angular-devkit/schematics   20.0.0-rc.2 (cli-only)
@angular/build               20.0.0-rc.2
@angular/cli                 20.0.0-rc.2
@schematics/angular          20.0.0-rc.2 (cli-only)
rxjs                         7.8.2
typescript                   5.8.3

Anything else relevant?

I also tried to configure the development configuration as the build target for the unit tests, but the same thing happens.

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