The Test Plan is not critical for Public-Comment, but is needed by Trial-Implementation. Having it in public-comment can help the reader understand how the IG is intended to be tested (or might be tested) at IHE-Connectathon. The initial draft of the test plan should identify an overall plan, tools that might need to be developed, data that might need to be developed, and a script that indicates the things that would need to happen in each test procedure.
The Test Plan is not critical for Public-Comment, but is needed by Trial-Implementation. Having it in public-comment can help the reader understand how the IG is intended to be tested (or might be tested) at IHE-Connectathon. The initial draft of the test plan should identify an overall plan, tools that might need to be developed, data that might need to be developed, and a script that indicates the things that would need to happen in each test procedure.
See QEDm as an example -- https://build.fhir.org/ig/IHE/QEDm/branches/master/testplan.html