`@angular/build:unit-test` with Vitest test runner throws `Failed to import test file` error

Start with the @angular/build:unit-test runner's providersFile handling and the generated init-testbed.js, then reproduce the failure using the linked minimal repository. Verify the fix by running ng test with TestService injecting Router and confirming that all specs import and pass without the JIT compiler error.

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

Steps to reproduce:

1. Create a TestService that will contain a single property router = inject(Router)
2. Configure @angular/build:unit-test runner to include providersFile
3. Export [TestService] from it
4. Create a Test component that will inject this service: service = inject(TestService)

ng test will fail with the following error for all specs:

FAIL   project (chromium)  path/to/some.spec.ts [ path/to/some.spec.ts ]
Error: Failed to import test file /project/root/init-testbed.js
Caused by: Error: The injectable '_PlatformLocation' needs to be compiled using the JIT compiler, but '@angular/compiler' is not available.

The injectable is part of a library that has been partially compiled.
However, the Angular Linker has not processed the library such that JIT compilation is used as fallback.

Ideally, the library is processed using the Angular Linker to become fully AOT compiled.
Alternatively, the JIT compiler should be loaded by bootstrapping using '@angular/platform-browser-dynamic' or '@angular/platform-server',
or manually provide the compiler with 'import "@angular/compiler";' before bootstrapping.
 ❯ <static_initializer> node_modules/.vite/vitest/dc540563f7f56f2cac74b38788615874d1da1c10/deps/chunk-42LDSDVL.js?v=049c4943:83:17

If you remove injection of the TestService from the Test component all the specs will start to pass.

Minimal Reproduction

https://github.com/th0r/ng-vitest-test-providers-bug

Your Environment

Angular CLI       : 21.0.1
Angular           : 21.0.2
Node.js           : 24.8.0
Package Manager   : npm 11.6.0
Operating System  : darwin arm64

┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package                   │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/build            │ 21.0.1            │ ^21.0.1           │
│ @angular/cli              │ 21.0.1            │ ^21.0.1           │
│ @angular/common           │ 21.0.2            │ ^21.0.0           │
│ @angular/compiler         │ 21.0.2            │ ^21.0.0           │
│ @angular/compiler-cli     │ 21.0.2            │ ^21.0.0           │
│ @angular/core             │ 21.0.2            │ ^21.0.0           │
│ @angular/forms            │ 21.0.2            │ ^21.0.0           │
│ @angular/platform-browser │ 21.0.2            │ ^21.0.0           │
│ @angular/router           │ 21.0.2            │ ^21.0.0           │
│ rxjs                      │ 7.8.2             │ ~7.8.0            │
│ typescript                │ 5.9.3             │ ~5.9.2            │
│ vitest                    │ 4.0.14            │ ^4.0.8            │
└───────────────────────────┴───────────────────┴───────────────────┘