Ts-jest: Parsing TypeScript namespace token

[bonham000]

• Issue

Running jest using ts-jest produces an error when it tries to parse a TypeScript namespace.

• Expected behavior

Jest should be able to parse the file normally without any error.

• Output from your debug log

      Jest encountered an unexpected token
      This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.
      By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".
      Here's what you can do:
       • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
       • If you need a custom transformation specify a "transform" option in your config.
       • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.
      You'll find more details and examples of these config options in the docs:
      https://facebook.github.io/jest/docs/en/configuration.html
      Details:
        153 | }
        154 |
      > 155 | export namespace QueryResolvers {
            |                  ^
        156 |   export interface Resolvers {
        157 |     user?: UserResolver;
        158 |     countries?: CountriesResolver;

Did I miss something in the Jest setup or is this not a support feature? I've looked elsewhere but was unable to find any similar discussions about this particular issue. Happy to provide a repo to reproduce if needed but I think it will be reproduced by importing from any TypeScript file which uses a namespace when using ts-jest.

[huafu]

Please yes provide a minimal repo, because your issue looks like a jest config issue where you'd forget the ts in moduleFileExtensions for example.

[bonham000]

I've managed to figure this out. The culprit was several configuration issues. Notes to anyone in the future (for reference this is within a TypeScript React Native project with Expo):

From jest.config.js:

module.exports = {
    preset: "jest-expo",
    globals: {
        "ts-jest": {
            "useBabelrc": true,
        }
    },
    transform: {
        "^.+\\.jsx?$": "<rootDir>/node_modules/babel-jest",
        "^.+\\.tsx?$": "ts-jest",
        "\\.(gql|graphql)$": "jest-transform-graphql",
    },
    // ... other config
}

I also had to enable this option in tsconfig.json:

"esModuleInterop": true,