feat(@angular-devkit/build-angular): enable sourcemaps by default when using karma

[alan-agius4]

I tried to do a regression tests like @filipesilva suggested

  it('sourcemaps are enabled by default', (done) => {
    host.writeMultipleFiles({
      'src/app/app.component.spec.ts': 'console.log(new Error())',
    });

    const logger = new TestLogger('karma-sourcemaps');

    runTargetSpec(host, karmaTargetSpec, undefined, DefaultTimeout, logger).pipe(
      tap((buildEvent) => expect(buildEvent.success).toBe(false)),
      tap(() => {
        console.log(logger);
        expect(logger.includes('/app/app.component.spec.ts')).toBe(true)
      }),
    ).toPromise().then(done, done.fail);
  });

However the problem is that the stacktrace always contains ts paths. The only difference when enabling sourcemaps is the contents of the files, as shown below;

Sourcemaps enabled

No sourcemaps

Closes #12282 and Potentially fixes #11672

[alan-agius4]

Seems like this solved the code coverage branch detection issue as well.

[filipesilva]

Yeah code coverage will never work without sourcemaps, so that makes sense.

[Teamop]

@filipesilva could this PR also merged to v6.x? seems right now it's just in the v7.

[filipesilva]

@Teamop unfortunately no, since it is a feature. Features only go on minor releases, and we don't plan on making another minor for 6.x. You can set the "sourceMap": true property on your test configuration and it will work the same though.

[TeoTN]

It was working fine with v~0.6.8 and stopped working with v6-lts and you call it a feature? I hit that error because I updated the lib with npm audit, I'd vastly appreciate if you could name it fix and add to Long Term Support release...

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}