Fails on lack of ts-jest even though it's optional

[Andarist]

It's states that ts-jest is an optional peer dep:

vue-jest/packages/vue3-jest/package.json

Lines 47 to 49 in 6edfa9c

	"ts-jest": {
	"optional": true
	},

However, @vue/vue3-jest cannot be used without it because if we have tsconfig.json then ts-jest is being required here:

vue-jest/packages/vue3-jest/lib/utils.js

Line 81 in 6edfa9c

const { ConfigSet } = require('ts-jest/dist/config/config-set')

Since my whole monorepo is using Babel I don't want to rely on the TypeScript compiler for transpilation purposes at all. It doesn't make sense because it could introduce subtle differences between the transpilation output in tests and in my app bundles.

I'd like to have a way to disable ts-jest completely and just use babel-jest for transpilation. I've already figured out that I can disable this part:

vue-jest/packages/vue3-jest/lib/process.js

Lines 21 to 22 in 6edfa9c

	if (/^typescript$|tsx?$/.test(lang)) {
	return transformer || typescriptTransformer

with a config such as this:

const { constants } = require('jest-config');

module.exports = {
  transform: {
    [constants.DEFAULT_JS_PATTERN]: 'babel-jest',
    '^.+\\.vue$': '@vue/vue3-jest',
  },
  globals: {
    'vue-jest': {
      // weird way of disabling ts-jest-based transformer
      transform: {
        '^typescript$': 'babel-jest',
        '^tsx?$': 'babel-jest'
      }
    }
  },
};

but then I've found out that ts-jest is still being required through here:

vue-jest/packages/vue3-jest/lib/process.js

Line 121 in 5741877

const tsconfig = getTsJestConfig(config)

So my current workaround for this is this:

const { constants } = require('jest-config');
const os = require('os');

module.exports = {
  transform: {
    [constants.DEFAULT_JS_PATTERN]: 'babel-jest',
    '^.+\\.vue$': '@vue/vue3-jest',
  },
  globals: {
    'vue-jest': {
      // weird way of disabling ts-jest-based transformer
      transform: {
        '^typescript$': 'babel-jest',
        '^tsx?$': 'babel-jest'
      },
      // redirect tsconfig lookup elsewhere so vue-jest doesn't attempt to load ts-jest at all
      tsConfig: os.tmpdir()
    }
  },
};

[miyanokomiya]

Same here.
I tried to switch from ts-jest to @swc/jest, but I failed due to lack of ts-jest.

https://github.com/miyanokomiya/blendic-svg/runs/5268921002?check_suite_focus=true

Although tests on Github Actions env failed, they passed on my local env(wsl2 ubuntu). I don't know why

[distor-sil3nt]

This issue is haunting me, too. When I try @Andarist solution and replace babel-jest with @swc/jest I get the error:

[vue-jest] Error: transformer must contain at least one process, preprocess, or postprocess method 

Any chance to remove this dependency on ts-jest?

[nogic1008]

In fact, ts-jest is only used to load TypeScript configs.
I'll create a PR that replace it to tsconfig package.