nx: Slow jest tests on Windows

Expected Behavior

Tests are execetued fast on Windows

Current Behavior

Tests are exectued slow on Windows

Failure Information (for bugs)

Problem is with ts-jest which from version to version become slower and slower. (I’ve written about it here: https://github.com/kulshekhar/ts-jest/issues/259#issuecomment-485784109)

Steps to Reproduce

I’ve made sample repo to demonstrate the problem https://github.com/Karql/angular-nx-slow-tests

Please read the README.md - every thing is in it.

Other

Only one work around I’ve found is set isolatedModules: true in ts-jest config. But for now there is now way to pass this option to JestBuilder https://github.com/nrwl/nx/blob/625b2837a806e02709bdbe7b45ce3b131760448c/packages/jest/src/builders/jest/jest.builder.ts

To achieve it I’ve made hacky post install script which add this options:

const fs = require('fs');
const path = require('path');

// WORKAROUND for performance issue with ts-jst on windows
// https://github.com/kulshekhar/ts-jest/issues/259

var jestBuilderPath = path.join(__dirname, "..", "node_modules", "@nrwl", "builders", "src", "jest", "jest.builder.js")
let jestBuilder = fs.readFileSync(jestBuilderPath, { encoding: 'utf8' });

if (jestBuilder.indexOf("isolatedModules") < 0) {
    jestBuilder = jestBuilder.replace("var tsJestConfig = {", "var tsJestConfig = {\n\t\t\tisolatedModules: true,");
    fs.writeFileSync(jestBuilderPath, jestBuilder);
}

Do you have any idea how to fix it?

In jest 24 there is native support for type script: https://jestjs.io/blog/2019/01/25/jest-24-refreshing-polished-typescript-friendly maybe this is the way? Please read the opinion one of the main ts-jest contributors https://github.com/kulshekhar/ts-jest/issues/961#issuecomment-458294885

Regards!