Cannot read property 'call' of undefined for configure adapter for Jest

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All common issues

• common issues

Notoriously common issues

• Webpack build issues
• Cannot find module ‘react-dom/lib/ReactTestUtils’
• Query Selector fails
• Testing third party libraries

If you haven’t found any duplicated issues, please report it with your environment!

Current behavior

● Test suite failed to run

We’ve recently updated a lot of packages(including jest, react etc.) but not enzyme. However this bug start appearing in the test setup file while it has not been changed.

    TypeError: Cannot read property 'call' of undefined

      6 | configure({ adapter: new Adapter()});
      7 |

      at forEach (node_modules/foreach/index.js:7:27)
      at defineProperties (node_modules/define-properties/index.js:52:19)
      at Object.<anonymous> (node_modules/object.assign/index.js:11:27)
      at Object.<anonymous> (node_modules/enzyme/build/ReactWrapper.js:23:15)
      at Object.<anonymous> (node_modules/enzyme/build/index.js:3:21)
      at Object.<anonymous> (test/config/setup-test.js:8:15)

This is the setup-test file.

/* Setup Enzyme with appropriate react adapter for testing */
import {configure} from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';


configure({ adapter: new Adapter()});

I logged all the way down at /foreach/index.js where the call fails.

var hasOwn = Object.prototype.hasOwnProperty;
var toString = Object.prototype.toString;

module.exports = function forEach (obj, fn, ctx) {
    if (toString.call(fn) !== '[object Function]') {

Weird thing is that toString is undefined, but hasOwn is a defined function.

This is our jest file

{
  "rootDir": "../../",
  "verbose": true,
  "setupFiles": ["<rootDir>/test/config/setup-test.js", "<rootDir>/test/config/setup-jsdom.js"],
  "testURL": "http://localhost/",
  "reporters": ["default", "jest-junit"],
  "roots": [
    "client",
    "test/unit/client"
  ],
  "moduleFileExtensions": [
    "js",
    "jsx"
  ],
  "moduleDirectories": [
    "node_modules"
  ],
  "modulePaths": [
    "client",
    "test/utils"
  ],
  "moduleNameMapper": {
    "\\.(css|less|scss)$": "<rootDir>/test/utils/empty-style-mock.js",
    "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/test/utils/empty-svg-mock.js"
  },
  "transformIgnorePatterns": [],
  "unmockedModulePathPatterns" : [
    "./node_modules/jasmine-reporters"
  ]
}

Expected behavior

Your environment

MAC OSX 10.13.6

API

• shallow
• mount
• render

Version

enzyme: “3.3.0”, enzyme-adapter-react-16: “1.1.1” react: “16.4.1” node: “v8.11.1” jest: “23.1.0” jsdom: “11.12.0”

Adapter

• enzyme-adapter-react-16
• enzyme-adapter-react-15
• enzyme-adapter-react-15.4
• enzyme-adapter-react-14
• enzyme-adapter-react-13
• enzyme-adapter-react-helper
• others ( )

[jonasfrid]

Not sure if it’s related, but I received a similar error (TypeError: Cannot read property 'prototype' of undefined) when using Enzyme + Jest. In the end, it turned out to have to do with how / what I exported from the component I was testing.

Simply put, the component was wired up via redux, but I wanted to shallow test it, so changed this:

class MyComponent extends Component {
  …
}
…
…
export default withRouter(connect(
  mapStateToProps,
  mapDispatchToProps
)(MyComponent))

to this:

export class MyComponent extends Component {
  …
}
…
…
export default withRouter(connect(
  mapStateToProps,
  mapDispatchToProps
)(MyComponent))

…but shallow-wrapping in my test (as below) kept failing with the mentioned error message

import {MyComponent as UnConnectedMyComponent} from '../question';
...
const wrapper = shallow(
  <UnConnectedMyComponent />
);

HOWEVER, then I realized that I had another, unnecessary export, before my class export in MyComponent:

export const myConstant = 'FOO'
…
…
export class MyComponent extends Component {
  …
}
…
…
export default withRouter(connect(
  mapStateToProps,
  mapDispatchToProps
)(MyComponent))

So, in the end, what was failing was that I duplicate exports from the component I was testing.

Not sure if this helps, but removing the export const myConstant = 'FOO' sorted my issue at least!

[ljharb]

@nicoxxie I’m going to close this, but I’m very interested in understanding why this is breaking for you, so it’d be great if you could follow up as you discover more.