angular/angular-cli · error · SchematicsException

Cannot add a karma configuration as builder for "test" targe

Error message

Cannot add a karma configuration as builder for "test" target in project does not use "${AngularBuilder.Karma}", "${AngularBuilder.BuildKarma}", or ${AngularBuilder.BuildUnitTest}.

What it means

The karma configuration generator only supports test targets built with one of three builders: `@angular-devkit/build-angular:karma` (`AngularBuilder.Karma`), `@angular-devkit/build-angular:build-karma` (`AngularBuilder.BuildKarma`), or `@angular/build:unit-test` (`AngularBuilder.BuildUnitTest`). If the `test` target uses any other builder, the schematic throws this exception because the generated `karma.conf.js` would not be recognized by the builder.

Source

Thrown at packages/schematics/angular/config/index.ts:135

      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 karma configuration.',
        );
      }

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

      testTarget.options ??= {};
      if (testTarget.builder !== AngularBuilder.BuildUnitTest) {
        testTarget.options.karmaConfig = path.join(project.root, 'karma.conf.js');
      } else {
        // `unit-test` uses the `runnerConfig` option which has configuration discovery if enabled
        testTarget.options.runnerConfig = true;

        let isKarmaRunnerConfigured = false;
        // Check runner option
        if (testTarget.options.runner) {
          if (testTarget.options.runner === 'karma') {
            isKarmaRunnerConfigured = true;
          } else {

View on GitHub (pinned to bb72145f9a)

Solutions

1. Switch the test target builder in angular.json to `@angular-devkit/build-angular:karma` or `@angular-devkit/build-angular:build-karma` (or `@angular/build:unit-test`) and re-run the schematic.
2. If you are using a non-Angular test runner (e.g. Jest), do not generate a karma config; configure that runner's own config file instead.
3. Verify the builder string in angular.json is not mistyped or referencing a builder that is not installed.

Example fix

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

const supported = [
  '@angular-devkit/build-angular:karma',
  '@angular-devkit/build-angular:build-karma',
  '@angular/build:unit-test',
];
const b = project.architect?.test?.builder;
if (b && !supported.includes(b)) {
  throw new Error(`Test target builder "${b}" is not supported for karma config generation.`);
}

function supportsKarmaConfig(builder: string | undefined): boolean {
  return builder === '@angular-devkit/build-angular:karma'
    || builder === '@angular-devkit/build-angular:build-karma'
    || builder === '@angular/build:unit-test';
}

try {
  await runSchematic('config', { project, type: 'karma' });
} catch (e) {
  if (e instanceof SchematicsException && e.message.includes('Cannot add a karma configuration')) {
    console.error('Use a supported karma/unit-test builder on the test target, or skip karma config for this runner.');
  } else throw e;
}

When it happens

Trigger: Running `ng generate config <project> --type karma` when the project's `test` target builder is something else entirely — e.g. a custom/third-party test builder, jest builder, or a mistyped builder string in angular.json.

Common situations: Workspaces using non-Karma test runners (Jest/Web Test Runner) whose test targets point at community builders; users attempting to attach a karma.conf.js to a vitest-runner-only unit-test target where the CLI then warns, or to a custom builder; partially migrated workspaces.

Related errors

• Cannot add a Vitest configuration as builder for "test" targ
• No "test" target found for project "${options.project}". A "
• Option "project" is required.
• Project is not defined in this workspace.
• Targets are not defined for this project.

AI-assisted analysis of angular/angular-cli@bb72145f9a (2026-08-30). Data as JSON: /api/errors/e9fea38a3fedd002. Report an issue: GitHub.