Jest module resolution

Jest module resolution doesn't use the ts file so some work needs to be done to align them.

Simple

In the simplest case where everything is just mapped from @/name to ./src/name


moduleNameMapper: {
'^@/(.\*)$': '<rootDir>/src/$1',
},

Advanced

Attempt to read the tsconfig and use it.


function makeModuleNameMapper(srcPath, tsconfigPath) {
  // Get paths from tsconfig
  const { paths } = require(tsconfigPath).compilerOptions
 
  const aliases = {}
 
  // Iterate over paths and convert them into moduleNameMapper format
  Object.keys(paths).forEach((item) => {
    const key = item.replace('/_', '/(._)')
    const path = paths[item][0].replace('/*', '/$1')
    aliases[key] = srcPath + '/' + path
  })
  return aliases
}
const TS_CONFIG_PATH = './tsconfig.json'
const SRC_PATH = '<rootDir>'
 
/** @type {import('jest').Config} */
const customJestConfig = {
  //.. rest of jest config
  moduleNameMapper: {
    ...makeModuleNameMapper(SRC_PATH, TS_CONFIG_PATH),
  },
}

Conclusion

Hopefully one of the two types of solutions resolves the module. In a worse case debugging might be made easier by logging out the modules as they are resolved and checking that the paths are good.