Every ExUnit test is dead in CI: the only mix test sits behind a needs: edge to a failing job

[hyperpolymath]

The finding

Every ExUnit test in this repository is dead in CI. Not failing — never
executed, while the workflow, the job and the check-run all still appear.

There is exactly one mix test invocation in the whole tree:

.github/workflows/tests.yml:347   run: mix test --include integration

It lives in the integration-tests job, which declares needs: [build-images].
Build Test Images fails. A needs: edge to a failing job does not fail the
dependent job — it makes it skipped.

Measured on the run for 3bf9674a:

Build Test Images    failure
Integration Tests    skipped      <- the only home of mix test

Why this matters more than a red suite

A red suite is visible. A needs:-skipped job looks like it participated: it is
listed, it has a name, it reports a conclusion. And a skipped conclusion
satisfies a required status check, so this can sit behind a green ruleset
indefinitely.

Concretely, it already has: test/unified-api-adapter-contract_test.exs is the
ABI wire-contract guard that #120 repointed from the dead src/abi/Types.idr
onto the live src/Hypatia/ABI/Types.idr, closing instance 21 of the
guard-reads-the-wrong-thing trap. That fix is correct in the tree and vacuous
in CI, and nothing anywhere said so.

Note also that mix test excludes 242 :verisim_data tests unconditionally
(test/test_helper.exs), so even once it runs, the denominator is ~83%.

Acceptance criteria

1. Integration Tests reaches conclusion success on a run against main — not
   skipped, not cancelled. Either fix build-images, or move mix test out
   from behind it into a job with no dependency on image building. The Elixir
   unit suite does not need ArangoDB; only the :integration-tagged subset does.
2. The fix is proven by a mutant: break one assertion in
   test/unified-api-adapter-contract_test.exs (e.g. change one expected
   connector name), push, and confirm the check goes red. Revert and confirm
   green. A suite that cannot be made to fail is not evidence it runs.
3. The run prints its denominator — the N tests, M failures line must appear
   in the log with N > 0. A zero-test run exits 0 and reads as success.
4. A workflow-level assertion that no job carrying a test runner can resolve
   skipped silently: either drop the needs: edge, or add a final job with
   if: always() that fails when needs.integration-tests.result == 'skipped'.
5. State plainly in the job or the README whether the 242 :verisim_data tests
   are in scope. If they stay excluded, the exclusion is named, not implicit.

Probe for re-checking this class of fault anywhere

git grep -n 'mix test\|cargo test\|zig build test\|bun test' -- .github/workflows
gh run view <run-id> --repo O/R --json jobs --jq '.jobs[]|"\(.conclusion)\t\(.name)"' | sort

Ask "did it execute", never "does it exist".

Found while preparing #835.

[hyperpolymath]

Cured by #842 (450734e on main) -- as a side effect, not by direct action.

This issue's mechanism was a needs: edge from integration-tests to a failing
build-images, making the only mix test in the repo resolve to skipped.
#842 cured the actions.lock fault that had tests.yml startup-dead (#837);
with the workflow alive, Build Test Images passes, so the edge is no
longer broken and the dependent job runs.

Measured, run 35770348007, job Integration Tests (success)

Step Run Elixir integration tests -> success. The step ran
mix test --include integration:

Excluding tags: [:verisim_data]
Finished in 14.3 seconds (4.6s async, 9.6s sync)
1593 tests, 0 failures, 242 excluded

1593 tests executed. Per the standing rule that a green suite proves nothing
without its denominator, that number -- not the job's conclusion -- is the
evidence. test/unified-api-adapter-contract_test.exs, the ABI wire-contract
guard #120 repointed onto the live src/Hypatia/ABI/Types.idr, is among them,
so the instance-21 fix is now genuinely exercised rather than correct-in-tree
and vacuous in CI.

The general lesson, which outlives this issue

A skipped conclusion satisfies a required status check, and a
startup-dead workflow reports no jobs at all. Both look like "not red" and
neither is evidence. When a cure lands upstream in a needs: DAG, the verdict
of every node below it re-opens and must be re-measured -- carrying forward
the old conclusions is how a tier stays dead after its cause is fixed.

The same re-measurement surfaced End-to-End Tests, which by the identical
mechanism had never executed either. It now runs and fails (docker compose
cannot find its configuration file, so the E2E suite is still skipped). That is
tracked separately as #843 -- this issue covers the ExUnit tier, which is now
demonstrably alive.

🤖 Generated with Claude Code

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