Make `UnexpectedNilError` un-rescueable from tests

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
ruby
Domain
testing

Research direction

Start by locating UnexpectedNilError and the not_nil! implementation, then inspect how the project invokes minitest or RSpec. Determine how tests can prevent a bare rescue => e from hiding this error without crashing the test runner. Done means the error remains unrescueable by ordinary test code while minitest and RSpec continue to run.

Written by the indexing model from the issue text.

Description

It currently inherits from Exception, so that a bare rescue => e doesn't unintentionally rescue it. We've already run into a real-world case where that proved useful, where a fork of the not_nil! implementation made it derive from StandardError, which indeed hid a test failure (only detected because we switched that copy of the code to use Type Toolkit).

To make it truly uncatchable, we can do something like throw Object.new. In a production app, this would crash your Rails app with UncaughtThrowError, so we'd have to limit it to tests. But we also don't want to crash minitest/RSpec, so we'd need to wrap the test runner in a catch call. We would need some kind of secret-ish tag to throw, that only the test runner can catch.

Dominant language
Ruby
Stars
3
Forks
5
Avg merge
8d 23h
Merged PRs (30d)
8

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