I created a sample project to write tests with Jest. I followed some tutorials.
I added a simple calculation function in a typescript file as below.
Calc.cs
export class Calc {
public add(num1: number, num2: number) : number {
return num1 + num2;
}
public subtract(num1: number, num2: number) : number {
return num1 - num2;
}
}
Then added a test file as below.
import { should } from 'chai';
import { Calc } from './Calc';
should();
let calc = new Calc();
test('adds 1 + 2 to equal 3', () => {
expect(calc.add(1, 2)).toBe(3);
});
Then I tried to run the tests as mentioned below. Then I got this error.
PS C:TestProject> npm t
[email protected] test C:TestProject jest
C:TestProject\node_modules\jest-haste-map\build\crawlers\node.js:49 names.forEach(file => { ^
TypeError: Cannot read property 'forEach' of undefined at default.readdir (C:\TestProject\node_modules\jest-haste-map\build\crawlers\node.js:49:13) at go$readdir$cb (C:\TestProject\node_modules\jest\node_modules\graceful-fs\graceful-fs.js:149:14) at FSReqWrap.oncomplete (fs.js:135:15) npm ERR! Test failed. See above for more details.
Then I browse to that file which shows an error and it is mentioned below.
