Store unusual test data for further analysis

[brendonj]

Some tests could benefit from further inspection to help understand occasional unusual behaviour (e.g. when something unusual happens regularly but too infrequently to observe by running the test a few times manually).

Can we store packet traces from tests if they meet some requirement (takes too long, goes too slowly, etc)?

Some things to consider:

• which traffic do we keep (from the test only? All traffic on that interface? Privacy issues?)
• where do we store it?
• how do we access it?