angular/angular-cli · error · SchematicsException

Cannot add a Vitest configuration as builder for "test" targ

Error message

Cannot add a Vitest configuration as builder for "test" target in project does not use "${AngularBuilder.BuildUnitTest}".

What it means

Even when a `test` target exists, `addVitestConfig` only supports projects whose test target uses the `@angular/build:unit-test` builder (`AngularBuilder.BuildUnitTest`). If the target uses any other builder (e.g. `@angular-devkit/build-angular:karma`), the schematic refuses to add a Vitest configuration because the generated `vitest-base.config.ts` would not be consumed. The grammatically garbled message means: the test target's builder must be the unit-test builder.

Source

Thrown at packages/schematics/angular/config/index.ts:62

function addVitestConfig(options: ConfigOptions): Rule {
  return (tree, context) =>
    updateWorkspace((workspace) => {
      const project = workspace.projects.get(options.project);
      if (!project) {
        throw new SchematicsException(`Project name "${options.project}" doesn't not exist.`);
      }

      const testTarget = project.targets.get('test');
      if (!testTarget) {
        throw new SchematicsException(
          `No "test" target found for project "${options.project}".` +
            ' A "test" target is required to generate a Vitest configuration.',
        );
      }

      if (testTarget.builder !== AngularBuilder.BuildUnitTest) {
        throw new SchematicsException(
          `Cannot add a Vitest configuration as builder for "test" target in project does not` +
            ` use "${AngularBuilder.BuildUnitTest}".`,
        );
      }

      testTarget.options ??= {};
      testTarget.options.runnerConfig = true;

      // Check runner option.
      if (testTarget.options.runner === 'karma') {
        context.logger.warn(
          `The "test" target is configured to use the "karma" runner in the main options.` +
            ' The generated "vitest-base.config.ts" file may not be used.',
        );
      }

      for (const [name, config] of Object.entries(testTarget.configurations ?? {})) {
        if (

View on GitHub (pinned to bb72145f9a)

Solutions

1. Change the test target builder in angular.json to `@angular/build:unit-test`, then re-run `ng generate config <project> --type vitest`.
2. Run the Angular CLI migration to the application builder / unit-test builder (`ng update @angular/cli`) if you are on an older workspace.
3. If you intend to stay on Karma, generate a karma configuration instead (`--type karma`) rather than a Vitest one.

Example fix

// angular.json before
"test": { "builder": "@angular-devkit/build-angular:karma", "options": { ... } }
// after
"test": { "builder": "@angular/build:unit-test", "options": { ... } }

const testTarget = project.architect?.test;
if (testTarget && testTarget.builder !== '@angular/build:unit-test') {
  throw new Error(`Test target builder is "${testTarget.builder}"; Vitest config requires "@angular/build:unit-test".`);
}

function usesUnitTestBuilder(t: { builder?: string } | undefined): boolean {
  return t?.builder === '@angular/build:unit-test';
}

try {
  await runSchematic('config', { project, type: 'vitest' });
} catch (e) {
  if (e instanceof SchematicsException && e.message.includes('Cannot add a Vitest configuration')) {
    console.error('Switch the test target builder to @angular/build:unit-test first.');
  } else throw e;
}

When it happens

Trigger: Running `ng generate config <project> --type vitest` when the project's `test` target builder is `@angular-devkit/build-angular:karma` or any builder other than `@angular/build:unit-test`.

Common situations: Projects migrated from Karma but still on the legacy karma builder; workspaces mixing old and new builder versions; users who upgraded Angular CLI partially so the new unit-test builder is unavailable; manually authored test targets pointing at a different builder.

Related errors

• No "test" target found for project "${options.project}". A "
• Cannot add a karma configuration as builder for "test" targe
• Project "${projectName}" uses a custom coverage reporter "${
• Project "${projectName}" uses a custom Karma configuration f
• The following Karma configuration files require manual migr

AI-assisted analysis of angular/angular-cli@bb72145f9a (2026-08-30). Data as JSON: /api/errors/77f8db1af978e0af. Report an issue: GitHub.