Vue Jest encountered an unexpected token but doesn't specify the token

Question

Several of my unit tests are failing to run with the following error:

    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:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/en/ecmascript-modules for how to enable it.
     • 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://jestjs.io/docs/en/configuration.html

    Details:

    SyntaxError: Unexpected token (9:80)

      at Parser.pp$4.raise (node_modules/vue-template-es2015-compiler/buble.js:2757:13)
      at Parser.pp.unexpected (node_modules/vue-template-es2015-compiler/buble.js:646:8)
      at Parser.pp$3.parseExprAtom (node_modules/vue-template-es2015-compiler/buble.js:2196:10)
      at Parser.<anonymous> (node_modules/vue-template-es2015-compiler/buble.js:6003:24)
      ...

My jest config is as follows:

{
    moduleFileExtensions: [
        'js',
        'jsx',
        'json',
        // tell Jest to handle *.vue files
        'vue',
    ],
    transform: {
        // process *.vue files with vue-jest
        '^.+\\.vue$': require.resolve('vue-jest'),
        '.+\\.(css|styl|less|sass|scss|png|jpg|svg|ttf|woff|woff2|PNG)$':
            'jest-transform-stub',
        '^.+\\.jsx?$': require.resolve('babel-jest'),
    },
    transformIgnorePatterns: ['node_modules/(?!bootstrap)'],
    // support the same @ -> src alias mapping in source code
    moduleNameMapper: {
        '^@/(.*)$': '<rootDir>/src/$1',
        '\\.(css|sass)$': 'identity-obj-proxy',
    },
    testEnvironment: 'jest-environment-jsdom-fifteen',
    // serializer for snapshots
    snapshotSerializers: ['jest-serializer-vue'],
    testMatch: [
        '**/tests/unit/**/*.spec.[jt]s?(x)',
        '**/__tests__/*.[jt]s?(x)',
    ],
    // https://github.com/facebook/jest/issues/6766
    testURL: 'http://localhost/',
    watchPlugins: [
        require.resolve('jest-watch-typeahead/filename'),
        require.resolve('jest-watch-typeahead/testname'),
    ]
}

I'm at a loss for how to debug this error when it doesn't seem to specify the actual token that's unexpected (unless it's whitespace) and it doesn't seem to be pointing to any compon

Agata

Answer 1

Fixed the issue - it was caused by using optional chaining (object?.property) within the Vue HTML template.

I had an html element using the following syntax:

<Component :name="data?.name" />

Using the ? optional chaining operator within the HTML template of my Single Page Component caused the Unexpected token error without it specifying that the ? was the unexpected token.

Agata

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. – Hillhouse