test(assessments): fix flaky title-sort tests via DB collation

[RichDom2185]

Problem

The submissions_by_grader_for_index title-sort tests are flaky. On PR #1377's CI they failed with:

Assertion with >= failed
code:  assert x.title >= y.title
left:  "I will speak daggers to her, but use none."
right: "In my mind's eye."

Root cause

The query sorts by upper(title) in the database, which uses PostgreSQL's locale collation:

order_by: [{^sort_direction, fragment("upper(?)", asst.title)}]

The tests then re-checked the returned order with Elixir's binary string comparison (assert x.title >= y.title). The two disagree on how spaces and punctuation sort relative to letters — e.g. PostgreSQL's collation orders "In my mind's eye." before "I will speak daggers to her, but use none." (ignoring the space), whereas Elixir's binary comparison does the opposite (space 0x20 < n).

Assessment titles are randomly generated Hamlet quotes (Faker.Lorem.Shakespeare.En.hamlet()), and Faker is not seeded, so whenever a run happened to produce two titles straddling this boundary, the test failed. Only the title sort tests are affected (type/xp sort by integers). String.upcase/1 alone would not fix it — the failing pair are both already uppercase-initial.

Fix

Assert the returned order against the database's own sort of the same titles, comparing upper(title) on both sides. This makes the check deterministic and consistent with the query under any collation, and it now verifies the full ordering rather than only that the first element is the extremum.

Verified locally: the helper passes for the DB-correct order (which the old binary check would have wrongly rejected) and fails for a reversed order. Ran the two tests across multiple random seeds and the full assessments_test.exs (90 tests) — all green.

Note

Stacked on #1377 (fix-course-creation-500) since it is unrelated to that course-creation fix. GitHub will retarget this PR to master once #1377 merges.

🤖 Generated with Claude Code

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 2950af00-dd29-40fb-9d87-ee9ab06c9897

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

coverage: 88.354% (-0.02%) from 88.376% — fix-flaky-submission-sort-test into master