Coverage report for jest unit tests not displaying with --coverage option

Question

My Project is based on Create-react-app setup and my package.json script for testing unit tests is as below

"scripts": {
    "test": "react-scripts test --coverage",
 }

or

 "test": "react-scripts test --coverage --collectCoverageFrom=src/**/*.{js,jsx}

It executes tests in Test folder but doesn't display coverage report.Can you help to solve this issue.

My file structure is as below src | --- Test ---components> moduleA > package1 > package2> transaction.js, abcd.js... etc

ProcessEvent.test.js

describe('ProcessEvent Component', () => {

    const expectedProps = {
        "event": {iconStatus:'active', desc:'abc'}
    }

    it('should render without error', () => {
        const component = <ProcessEvent {...expectedProps}/>
        const wrapper = component.find('.eventclass');
        expect(wrapper.length).toBe(1);
    });

    it('should receive valid props', () => {
        const component = shallow(<ProcessEvent {...expectedProps}/>);
        const wrapper = component.find('.eventclass');
        expect(component.props).toBeDefined();
    });

});

Can you post some examples of your tests? Could you try running your tests directly with jest? i.e. "jest --coverage" — dyouberg
– dyouberg, Commented Oct 21, 2019 at 15:35
Hi @dyouberg, to use "jest --coverage" I will have to eject out of create-react-app setup, which I dont want to do. Now it says 'jest can not parse file' — Shrikant Dande
– Shrikant Dande, Commented Oct 21, 2019 at 16:02
Ok, fair enough. It looks like the coverage utility is running correctly, could you post examples of your tests? Maybe that's where the problem is — dyouberg
– dyouberg, Commented Oct 21, 2019 at 16:04
I have added my ProcessEvent.test.js component I have similar 3 other test components. — Shrikant Dande
– Shrikant Dande, Commented Oct 21, 2019 at 16:14

Sujit Y. Kulkarni · Accepted Answer · 2020-06-11 12:39:28Z

2

Using --watchAll=false parameter makes it list down all the files.

Example package.json

{
...
"scripts": {
    "start": "react-app-rewired start",
    "build": "react-app-rewired build",
    "test": "react-app-rewired test",
    "coverage": "react-app-rewired test -- --coverage --watchAll=false",
    "eject": "react-scripts eject",
    "serve": "node server.js"
  },
...
}

Also your coverage report is physically located at /coverage/lcov-report. Opening an index.html located there, would show you the coverage report in your browser.

answered Jun 11, 2020 at 12:39

Sujit Y. Kulkarni

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1 Comment

Arinze Ogbonna Over a year ago

I was facing this kind of issue too using --watchAll=false did print out the result on my console put the generated report was still showing empty... do you have any idea what will be causing it?

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