@web/test-runner-mocha
Advanced tools
Test framework implementation of Mocha for Web Test Runner
See @web/test-runner for a default implementation and CLI for the test runner.
Mocha relies on global variables, in any JS test file describe and it are available globally and can be used directly:
describe('my test', () => {
it('foo is bar', () => {
if ('foo' !== 'bar') {
throw new Error('foo does not equal bar');
}
});
});
If you're writing tests as HTML, you can import this library to run tests with mocha.
You can write tests inline in the HTML page
<html>
<body>
<script type="module">
import { mocha, sessionFinished, sessionFailed } from '@web/test-runner-mocha';
try {
// setup mocha
mocha.setup({ ui: 'bdd' });
// write your actual tests
describe('HTML tests', () => {
it('works', () => {
expect('foo').to.equal('foo');
});
});
// run the tests, and notify the test runner after finishing
mocha.run(() => {
sessionFinished();
});
} catch (error) {
console.error(error);
// notify the test runner about errors
sessionFailed(error);
}
</script>
</body>
</html>
You can also use dynamic imports to load tests written in JS from the HTML page.
<html>
<body>
<script type="module">
import { mocha, sessionFinished } from '@web/test-runner-mocha';
async function run() {
try {
// setup mocha
mocha.setup({ ui: 'bdd' });
// import your tests
await import('./my-test.js');
// run the tests, and notify the test runner after finishing
mocha.run(() => {
sessionFinished();
});
} catch (error) {
console.error(error);
// notify the test runner about errors
sessionFailed(error);
}
}
run();
</script>
</body>
</html>
From the HTML page you can load polyfills or libraries to be set up before your tests are run. This is great for testing your code in different environments.
<html>
<body>
<script src="./some-polyfill.js"></script>
<script type="module">
import { mocha, sessionFinished } from '@web/test-runner-mocha';
// see examples above
</script>
</body>
</html>
You can use elements in the <head> to configure different browser environment, such as base path or CSP rules.
<html>
<head>
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self'; img-src https://*; child-src 'none';"
/>
</head>
<body>
<script type="module">
import { mocha, sessionFinished } from '@web/test-runner-mocha';
// see examples above
</script>
</body>
</html>
You can configure mocha options using the testFramework.config option:
module.exports = {
testFramework: {
config: {
ui: 'bdd',
timeout: '2000',
},
},
};
The config entry accepts any of the official mocha browser options.
@open-wc/testing is a general purpose library, including assertions via chai, HTML test fixtures, a11y tests and test helpers.
It is an opinionated implementation which brings together multiple libraries. You could also use the individual libraries together:
For stubbing and mocking, we recommend sinon which ships an es module variant out of the box:
import { stub, useFakeTimers } from 'sinon';
FAQs
Mocha test framework for Web Test Runner
The npm package @web/test-runner-mocha receives a total of 67,040 weekly downloads. As such, @web/test-runner-mocha popularity was classified as popular.
We found that @web/test-runner-mocha demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 7 open source maintainers collaborating on the project.
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