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

先從檢查 @angular/build:unit-test runner 對 providersFile 的處理以及產生的 init-testbed.js 開始，然後使用連結的最小儲存庫重現該失敗。透過執行 ng test（其中 TestService 注入 Router），並確認所有 spec 都能在不出現 JIT 編譯器錯誤的情況下匯入並通過，來驗證修正。

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            │
└───────────────────────────┴───────────────────┴───────────────────┘