Migration Fails to Grab `testMatch`

[Karl-EdwardJeanMehu]

🐛 Bug Report

After running the latest version of ts-jest with the config:migration command, the testMatch option is set to null despite its value in the config file, jest.config.js.

Expected behavior

The testMatch option in the migrated configuration should have the same value set in the jest.config.js file.

Pre-migration config:

module.exports = {
  clearMocks: true,
  collectCoverage: false,
  coverageProvider: "v8",
  preset: "ts-jest/presets/js-with-ts",
  testEnvironment: "node",
  testMatch: [
    "**/__tests__/**/*.(spec|test).[tj]s?(x)"
  ]
}

Post-migration ( from jest.config.js ) config:

Migrated Jest configuration:
module.exports = {
  clearMocks: true,
  collectCoverage: false,
  coverageProvider: 'v8',
  preset: 'ts-jest/presets/js-with-ts',
  testEnvironment: 'node',
  testMatch: null,
  testRegex: [],
}

Notice testMatch is set to null.

To Reproduce

Save pre-migration configs to jest.config.js file then run yarn ts-jest config:migrate jest.config.js

envinfo

System:
    OS: MacOS
    Node version: v14.15.3

Npm packages:
    jest: v26.6.3
    ts-jest: v26.5.6
    typescript: v3.9.6