Support for the new `action_dispatch.show_exceptions` values was
introduced in [e28f147][]. Alongside the change to introduce new values
(like `:all`, `:rescuable`, `:none`), the default behavior was changed
for `Rails.env.test?`.
Prior to that commit, the `test` environment's default value was `false`
(introduced in [d898a4b][]) (which corresponds to the new `:none`
setting).
The new default behavior has some unintended negative side effects that
impact the feedback loop at the core of test-driven development.
When errors are rescued and transformed into HTML pages, the context of
the cause of failure is obscured by additional layers of information.
First, this commit adds more prominent entries to the Upgrading and
Configuring guides, as well as the 7.1 Release Notes to document the
details of the configuration and its new values.
Next, this commit adds more documentation around the change in default
behavior. To start, it mentions the new value in the sections for the
affected test types: Controller, Integration, and System.
[e28f147]: e28f147329
[d898a4b]: d898a4ba42
723e69c857