[hkwerf]

I ship containers to customers. Would be nice to run tests against them before releasing a container and it would be nice if those tests themselves could run in a container in order to have a clean test environment.

[codethief]

…and to re-use cached image layers and speed up the pipeline!

[sgsag33]

You could create that test environment image beforehand, mirror it and use it for the job that needs it. No need for adding another container within a container.