# `Surfex.ExUnitFormatter`
[🔗](https://github.com/dcoai/surfex/blob/v0.6.2/lib/surfex/ex_unit_formatter.ex#L1)

An ExUnit formatter that records test evidence (`Surfex.Evidence`): for each test that
ran, whether it passed, at its exact version, with the versions of the code it calls.

Add it beside the usual formatter, in `test/test_helper.exs`:

    ExUnit.start(formatters: [ExUnit.CLIFormatter, Surfex.ExUnitFormatter])

At the start of the suite it scans the project as `mix surfex.status` does: the tests
`tests:` names in `.surfex.exs`, and the code. A finished test is matched to its scanned
record by file and line, so a test a comprehension generates counts for the record that
defines it. When a record's test ran more than once in a run (one per case), it failed
if any case failed. An excluded or skipped test is recorded as such, with no code
versions, so a run that leaves a test out is told apart from one where it didn't run.
Invalid tests, and tests outside `tests:`, record nothing. When the suite finishes, the run's records are appended to
`Surfex.Evidence.path/1` under `_build`: scratch data, never committed.

It never touches the relation log. Evidence justifies confirmations only when someone
asks for them (`mix surfex.confirm --evidence`).

# `child_spec`

Returns a specification to start this module under a supervisor.

See `Supervisor`.

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*Consult [api-reference.md](api-reference.md) for complete listing*