Demonstrating memory leak in react-router with Redirect component in jest and JSDOM

This applies as of v6.22.3 of react-router.

How to reproduce

Setup

Install all dependencies with npm ci.

Note that it will patch the jest-runner package to take a heap snapshot after each test is completely torn down. These heap snapshots will be placed in your current working directory.

Run tests (with and without <Redirect />)

run npm run test-with-redirect and npm run test-without-redirect.

You might want to rename the heap snapshots after running each of the scripts so that you don't confuse them.

Analyze heap snapshots

Load heap snapshot into Chrome dev tools (open dev tools, go to "memory" tab, import snapshot by clicking the "load profile" button (CMD + O)).

In the snapshot that uses the <Redirect />, you will find 4 Window objects still in memory. In the other snapshot, there will be no Window objects still in memory.