I'm developing in React Native and trying to set up jest testing by following the directions at https://airbnb.io/enzyme/docs/guides/react-native.html.
I think I've set everything up correctly. Here's my config:
//setup-tests.js
import "react-native";
import "jest-enzyme";
import Adapter from "enzyme-adapter-react-16";
import Enzyme from "enzyme";
// Set up DOM in node.js environment for Enzyme to mount to
const { JSDOM } = require("jsdom");
const jsdom = new JSDOM("<!doctype html><html><body></body></html>");
const { window } = jsdom;
function copyProps(src, target) {
Object.defineProperties(target, {
...Object.getOwnPropertyDescriptors(src),
...Object.getOwnPropertyDescriptors(target)
});
}
global.window = window;
global.document = window.document;
global.navigator = {
userAgent: "node.js"
};
copyProps(window, global);
// Set up Enzyme to mount to DOM, simulate events, and inspect the DOM in tests.
Enzyme.configure({ adapter: new Adapter() });
/* Ignore some expected warnings
* see: https://jestjs.io/docs/en/tutorial-react.html#snapshot-testing-with-mocks-enzyme-and-react-16
* see https://github.com/Root-App/react-native-mock-render/issues/6
*/
const originalConsoleError = console.error;
console.error = message => {
if (message.startsWith("Warning:")) {
return;
}
originalConsoleError(message);
};
// jest.config.js
module.exports = {
setupFilesAfterEnv: "<rootDir>setup-tests.js"
};
// Test.test.js
import React from "react";
import renderer from "react-test-renderer";
import { mount, ReactWrapper } from "enzyme";
import { Provider } from "react-redux";
import { Text } from "react-native";
import LoginView from '../js/LoginView'
You'll see the top of LoginView in a moment.
You'll notice that I haven't even written any tests in the test file, I'm just trying to get jest running to the point where it can evaluate a test.
Without the import LoginView, jest runs and "fails" because my test suite must contain at least one test. Sounds good.
Adding in the import LoginView, I get this error (which shows the import statements at the top of LoginView:
import Button from './buttons/Button';
^^^^^^
SyntaxError: Unexpected identifier
1 | import React, { Component } from "react";
> 2 | import { Input, Button, Image } from "react-native-elements";
| ^
3 | import { Text, View } from "react-native";
4 | import { connect } from "react-redux";
5 | import F8StyleSheet from "./F8StyleSheet";
at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:471:17)
at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:513:25)
at Object.<anonymous> (js/LoginView.js:2:1)
So this doesn't make sense to me for a number of reasons.
LoginViewrenders fine in the actual app, with no "Unexpected identifier" crashes or warnings or anything- The lower arrows in the error on line 2 point to
import, which of course shouldn't be unexpected. - Then there's the upper arrows that indicate a line from
react-native-elements, so, I don't know about that.
Now, it does occur to me that the jest.config.js file did require me to use module.exports, and fails/crashes when I tried using export default { setupFiles } (or however I tried to do it, allowing VS Code to update it to ES6 syntax). So maybe that's why it's not liking import.
Even if that's the case, I don't know what the heck to do next.
Update
I put in the code suggested in Brian's answer, and I'm now getting all new errors. Even though the errors suggest fixes, it doesn't seem to help –- I've added the following to my package.json under jest. I'm not sure where Dimensions.js is anyway; plus, I would assume that all this setup I'm doing for React Native in particular would know how to identify the convention of having file.ios.js and file.android.js be equivalent to file.
Here's my "fix" following the instructions, which doesn't help at all.
"moduleFileExtensions": [
"js",
"json",
"jsx",
"ts",
"tsx",
"node",
"ios.js",
"android.js"
]
And here's the new errors.
FAIL tests/Test.test.js
● Test suite failed to run
Cannot find module './Platform' from 'Dimensions.js'
However, Jest was able to find:
'./Platform.android.js'
'./Platform.ios.js'
You might want to include a file extension in your import, or update your 'moduleFileExtensions', which is currently ['js', 'json', 'jsx', 'ts', 'tsx', 'node'].
See https://jestjs.io/docs/en/configuration#modulefileextensions-array-string
However, Jest was able to find:
'../Utilities/Dimensions.js'
You might want to include a file extension in your import, or update your 'moduleFileExtensions', which is currently ['js', 'json', 'jsx', 'ts', 'tsx', 'node'].
See https://jestjs.io/docs/en/configuration#modulefileextensions-array-string
However, Jest was able to find:
'buttons/Button.js'
You might want to include a file extension in your import, or update your 'moduleFileExtensions', which is currently ['js', 'json', 'jsx', 'ts', 'tsx', 'node'].
See https://jestjs.io/docs/en/configuration#modulefileextensions-array-string
However, Jest was able to find:
'../js/LoginView.js'
You might want to include a file extension in your import, or update your 'moduleFileExtensions', which is currently ['js', 'json', 'jsx', 'ts', 'tsx', 'node'].
See https://jestjs.io/docs/en/configuration#modulefileextensions-array-string
at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:229:17)
at Object.require (node_modules/react-native/Libraries/Utilities/Dimensions.js:14:18)
