Create a hosted npm repo. Publish a package to it.
Create a proxy of the hosted npm repo. Get /-/all from the proxy.
Verify the metadata from the proxy matches the hosted contents.
Expire the metadata in the proxy. ie. :
- change all the cache values to zero
- change the remote url to point to another empty hosted npm repo
- run expire cache on the proxy repo
Send another request to Get /-/all - the same metadata is returned from the npm proxy.