Option for verbose report of passing assertions

Currently, the passing tests simply show up in a simple list. A flag (e.g. `--verbose`) should be provided so that each expected item within the passing test can be inspected. Examples where this is useful:
* test passes under multiple conditions that are discernible from the assertions
* report information can be further used (part of the response, the result of test fixtures, etc)

No file, test, or entry point is named. Start by locating the code that formats passing-test reports and gathers assertion results; done means a verbose flag exposes each expected item and preserves the existing simple list by default.

Written by the indexing model from the issue text.