Write a regression test from a bug report

A bug is fixed and you want it to stay fixed.

Write a regression test for the bug below.

1. State the exact behaviour the test must lock in, in one sentence.
2. Identify the minimum setup needed to reproduce it. Strip anything incidental from the original report.
3. Write the test. It must fail against the old code and pass against the fix. Say which line would have failed before.
4. Name the class of bug this belongs to, and suggest one or two neighbouring tests covering the same class, since bugs like this rarely occur alone.
5. Say where the test belongs: unit, integration, or end to end, and why that level is the one that would have caught it.

If the bug report lacks the detail needed to reproduce it, list the specific questions to ask rather than guessing.

Bug report:


The fix:

Failing and flaky tests. Diagnosing a red run, stabilising a flake, and locking a fixed bug in with a regression test.