Realm Jest tests do not work with React Native

I cannot run snapshot tests because when Realm is imported along with React Native I get following error:

    SyntaxError: Unexpected token import

      at transformAndBuildScript (node_modules/jest-runtime/build/transform.js:284:10)
      at Object.<anonymous> (node_modules/realm/lib/index.js:30:24)

This simple example shows the problem. It passes until you uncomment import 'react-native' line

'use strict'

// import 'react-native'
import Realm from 'realm'

describe('Realm-RN', () => {
  it('should pass', () => {
    expect(true).toEqual(true)
  })
})

[billpatterson]

Making this change to my (react native) project’s package.json file fixed it for me:

"jest": { "preset": "react-native", "transformIgnorePatterns": ["node_modules/(?!react-native|tcomb-form-native|apsl-react-native-button|react|realm)"] },

This was based on a message spit out by ‘npm test’ that said this was the updated version of preprocessorIgnorePatterns.

Don’t really have any understanding of what’s going on here. Just posting a “this helped me” comment.

[johannesschirrmeister]

Let me chime in with some half knowledge: Adding ‘node_modules/realm’ to preprocessorIgnorePatterns solved this issue for me.

Example: "preprocessorIgnorePatterns": [ "node_modules/(?!react-native|react|realm)" ]

Vague attempt of an explanation: Something goes wrong when transpiling Realm, but that step isn’t necessary and we solve the problem by skipping that step.