Running @angular/build:unit-test with `--include=` should only compile the included tests

Start with the @angular/build:unit-test executor and the angular.json test configuration, then compare how --include is handled against the include patterns in libs/ui-components/tsconfig.spec.json. Use the provided yarn ng test command and verify that only the selected spec and its dependencies are compiled, so unrelated test errors no longer block it and build time is reduced.

Command

test

Is this a regression?

No, it has been present since the @angular/build:unit-test builder was created.

Description

When I run:

yarn ng test ui-components --include=libs/ui-components/shortcuts/src/ShortcutEventsPlugin.spec.ts --watch=false

with angular.json config:

    "ui-components": {
      "projectType": "library"
      },
      "root": "libs/ui-components",
      "sourceRoot": "libs/ui-components",
      "prefix": "ui",
      "architect": {
        "build": {
          "builder": "@angular/build:ng-packagr",
          "options": {
            "project": "libs/ui-components/ng-package.json",
            "tsConfig": "libs/ui-components/tsconfig.lib.json"
          }
        },
        "test": {
          "builder": "@angular/build:unit-test",
          "options": {
            "buildTarget": "ui-components:build",
            "include": [
              "**/*.spec.ts"
            ],
            "tsConfig": "libs/ui-components/tsconfig.spec.json",
            "runnerConfig": "libs/ui-components/vitest.config.ts"
          }
        }
      }
    }

the @angular/build:unit-test executor (re)compiles all test files (**/*.spec.ts) in the library and those files' dependencies, even though only the included files are needed for the tests that are being run.

This creates 2 problems, aside from being wasteful:

• This slows down our test/fix loops by a factor of about 2 relative to just compiling the included files, though obviously the speedup depends on the size of the project and other things
• Compile errors in other tests prevent a developer from being able to run the tests they're working on

We use single file testing extensively during development, and we also have agent instructions to run tests with --include, so this causes significant problems for us.

Minimal Reproduction

In a larger project using @angular/build:unit-test, pick a single test file to run using --include, and run it:

yarn ng test (my-project) --include=(repo path to spec file) --watch=false

And note that mount of time building before running the test. You can also edit another test file in the project to break compilation, and note that you cannot run the first test file.

Then, edit the tsconfig.json.spec, replacing the wildcard patterns with the path to the file(s) being tested. Eg change:

// libs/ui-components/tsconfig.spec.json 
  "include": [
    "**/*.spec.ts",
    "**/*.d.ts",
    "**/*.*tests.ts"
  ],

to

  "include": [
    "shortcuts/src/ShortcutEventsPlugin.spec.ts",
    // "**/*.spec.ts",
    // "**/*.d.ts",
    // "**/*.*tests.ts"
  ],

And re-run the test command with --include. Notice the reduced time building (Eg I see 12s -> 4s) before the tests are run, and also that compile errors in other tests don't block running a test.

NOTE: The performance impact of this behavioral bug increases with the size of the project, so it's not really feasible to create a minimal repro for that. However if you need a minimal repro repo showing that single file tests can't be run when there is a compile error in another test, I can provide one.

Your Environment

Angular CLI       : 22.0.8
Angular           : 22.0.8
Node.js           : 24.16.0
Package Manager   : yarn 4.18.0
Operating System  : win32 x64

┌────────────────────────────┬───────────────────┬───────────────────┐
│ Package                    │ Installed Version │ Requested Version │
├────────────────────────────┼───────────────────┼───────────────────┤
│ @angular-devkit/core       │ 22.0.8            │ catalog:          │
│ @angular-devkit/schematics │ 22.0.8            │ catalog:          │
│ @angular/animations        │ 22.0.8            │ catalog:          │
│ @angular/build             │ 22.0.8            │ catalog:          │
│ @angular/cdk               │ 22.0.6            │ catalog:          │
│ @angular/cli               │ 22.0.8            │ catalog:          │
│ @angular/common            │ 22.0.8            │ catalog:          │
│ @angular/compiler          │ 22.0.8            │ catalog:          │
│ @angular/compiler-cli      │ 22.0.8            │ catalog:          │
│ @angular/core              │ 22.0.8            │ catalog:          │
│ @angular/forms             │ 22.0.8            │ catalog:          │
│ @angular/language-service  │ 22.0.8            │ catalog:          │
│ @angular/platform-browser  │ 22.0.8            │ catalog:          │
│ @angular/router            │ 22.0.8            │ catalog:          │
│ @schematics/angular        │ 22.0.8            │ catalog:          │
│ ng-packagr                 │ 22.0.2            │ catalog:          │
│ rxjs                       │ 7.8.2             │ catalog:          │
│ typescript                 │ 6.0.3             │ catalog:          │
│ vitest                     │ 4.1.8             │ catalog:          │
└────────────────────────────┴───────────────────┴───────────────────┘

Anything else relevant?

No response