jest-preset-angular: [Bug]: 12.2.2 breaks branch coverage

Version

12.2.2

Steps to reproduce

Create a sample class with decorator like this

import { Pipe, PipeTransform } from '@angular/core';
import { ConfigService } from './config.service';
 
@Pipe({
  name: 'config',
})
export class ConfigPipe implements PipeTransform {
  constructor(private service: ConfigService) {}

Execute and wondering why there are four branches.

Expected behavior

Expect that there are still zero branches.

Actual behavior

Four branches are counted.

Additional context

No response

Environment

System:
    OS: Windows 10 10.0.19043
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
  Binaries:
    Node: 16.14.2 - C:\nodejs\node.EXE
    npm: 8.5.0 - C:\nodejs\npm.CMD
  npmPackages:
    jest: ~28.1.0 => 28.1.3

About this issue

Original URL
State: closed
Created 2 years ago
Comments: 19 (5 by maintainers)

Most upvoted comments

I can confirm the issue is related to the forgotten emitDecoratorMetadata in our case. Fun fact the angular migration does not remove it automatically from the existing tsconfig.json files.

CSchulz on Sep 21, 2022

Angular 12 removed the need of emitDecoratorMetadata so I think that was why the example app doesn’t have it. That option in general shouldn’t be needed anymore.

FYI with that option true, the emitted codes will be like in this example https://www.typescriptlang.org/tsconfig#emitDecoratorMetadata, and notice that design:paramtypes is in emitted codes. This design:paramtypes was replaced in the workaround mentioned in https://github.com/istanbuljs/istanbuljs/issues/70#issuecomment-975654329

ahnpnl on Sep 19, 2022

I think it’s more on Istanbul side to solve it completely. The solution which alters the compiled output looks to me like a workaround rather than a right way. I think we should push Istanbul to fix it.

In the meantime, maybe using v8 coverage is better?

ahnpnl on Sep 13, 2022

Oh man, I just hit this today, upgrading Angular from 14.1.0 to 14.2.2. Glad it’s not just me. That issue in istanbul is like 5 years old though, so it’s curious that a bug that old would rear its head with a minor angular version update. @mandarini did you have success with v8?

michaelfaith on Sep 15, 2022

It seems that some transitive dependency produces different transformed result. There is nice work and writeup by @mandarini on https://github.com/mandarini/isolatedm-jest

Would it be possible to consider incorporating work above into jest-preset-angular (maybe under additional option)? It would simplify patching huge workspaces with many projects.

minijus on Sep 13, 2022