3044a38d1c
M2.5's gate, built before the milestone it gates -- the same order that put
`expectEvents` before the free list in M1 and Tier 0 before everything in M2.
`mongodb/specifications` has no aggregation suite, which is amendment A6's
central finding, so this milestone has to bring its own. The hazard in a corpus
we author is obvious and fatal: it can encode our own bugs as expectations and
then agree with us forever. So the split is enforced by the tooling.
`sources/*.json` holds documents and pipelines and nothing else; `record.js`
asks a real mongod 8.3.7 what each pipeline answers and writes the unified-
format file from the reply. Inputs authored, expectations measured -- the
discipline that corrected three assumptions in M1's session work and every
error code in M2, where the alternative would have shipped both times.
No second runner. `run.js --suite-dir` points the existing one somewhere else,
so the entity model, the matchers, the skip accounting and `expectEvents` come
for free; a second runner would drift from the first exactly where it mattered.
`--scorecard` is refused with `--suite-dir`, because `scorecard.txt` is the crud
corpus's record and the milestones are compared against it -- writing it from an
unrelated run would replace that record silently.
Errors record the code and not the message: message text is mongod's to change
between releases. Group pipelines end in a `$sort`, because group output order
is unspecified and a case depending on it would fail for the wrong reason on
either server.
The first source covers `$group`: nine accumulators including the edge cases
that decide an implementation -- `$avg` over a group whose values are not
numbers, `$min` of a field no document has, `$push` skipping a missing field,
`$first`/`$last` against input order, grouping on an array, a compound `_id`.
Where it starts, run against the M2 tip:
group-accumulators.json 9 pass 10 fail 0 skip
The nine include the four refusals M2 added, which answer with mongod's own
codes -- so the corpus already confirms that half. The ten are the milestone.
The crud corpus is unchanged at 201/90/196.
The aggregation corpus
mongodb/specifications has no aggregation suite. The thirteen
aggregate-*.json files this project runs come from crud and test the
aggregate command — cursors, read concern, the write stages, collation,
let. They touch stages barely and expressions not at all: $lookup,
$unwind, $facet, $addFields and $replaceRoot appear nowhere in the
pinned corpus. That is PLAN amendment A6, and this directory is its
consequence: M2.5 has to bring its own gate.
The one rule
Inputs are authored here; expectations are measured against a real mongod.
A corpus we write is a corpus that can encode our own bugs as expectations, and
it would then agree with us forever. So sources/*.json holds documents and
pipelines and nothing else, and record.js asks mongod 8.3.7 what each pipeline
answers. It is the same discipline that corrected three assumptions in M1's
session work and every error code in M2 — the alternative, in both cases, would
have shipped.
Running it
node tests/spec/run.js --suite-dir tests/spec/aggregate
The same runner as the crud corpus, pointed elsewhere. Sharing it is the point:
the entity model, the matchers, the skip accounting and expectEvents come for
free, and a second runner would drift from the first exactly where it mattered.
--scorecard is refused with --suite-dir: tests/spec/scorecard.txt is the
crud corpus's record and the milestones are compared against it.
Re-recording
mongod --port 27099 --dbpath /tmp/mongo-corpus &
node tests/spec/aggregate/record.js --mongod-port 27099
Writes <name>.json for every sources/<name>.json. The generated files are
committed: they are the corpus, and regenerating them is how a disagreement
with mongod gets re-measured rather than argued about.
Two things to know when adding cases:
- End a
$grouppipeline with a$sort. Group output order is unspecified, and a case that depended on it would fail for the wrong reason on either server. - Errors record the code, not the message. Message text is mongod's to change between releases; a corpus that pinned it would break for the wrong reason.
Leave out any case whose answer depends on a server newer than the 4.4 this server reports — recording it from mongod 8.x and judging it against a 4.4 answer measures the version gap, not the engine.
Where it stands
Recorded against mongod 8.3.7, run against the M2 tip:
group-accumulators.json 9 pass 10 fail 0 skip
The nine include the four refusals M2 added, which answer with mongod's own
codes. The ten are M2.5's work: $avg, $min, $max, $first, $last,
$push, $addToSet, $count, and a compound _id.