Sentry is an open-source JavaScript SDK published by Sentry to enable error tracking that helps developers monitor and fix crashes in real time.
However, when building tests for your application, you want to assert that the right flow-tracking or error is being sent to Sentry, but without really sending it to Sentry servers. This way you won't swamp Sentry with false reports during test running and other CI operations.

Sentry Testkit enables Sentry to work natively in your application, and by overriding the default Sentry transport mechanism, the report is not really sent but rather logged locally into memory. In this way, the logged reports can be fetched later for your own usage, verification, or any other use you may have in your local developing/testing environment.

npm install sentry-testkit --save-dev

const sentryTestkit = require('sentry-testkit')

const {testkit, sentryTransport} = sentryTestkit()

// initialize your Sentry instance with sentryTransport
Sentry.init({
    dsn: 'some_dummy_dsn',
    transport: sentryTransport,
    //... other configurations
})

// then run any scenario that should call Sentry.catchException(...)

expect(testKit.reports()).toHaveLength(1)
const report = testKit.reports()[0]
expect(report).toHaveProperty(...)

You may see more usage examples in the testing section of this repository as well.

See full API description and documentation here: https://wix.github.io/sentry-testkit/

Of Course! sentry-testkit have full support in both @sentry/browser and @sentry/node since they have the same API and lifecycle under the hood.

The good old legacy raven-testkit documentation can be found here. It it still there to serve Raven which is the old legacy SDK of Sentry for JavaScript/Node.js platforms