37cfa863ee
The whole corpus is green: 46 pass, 0 fail, byte-identical to mongod 8.3.7 on
every case including all 27 expressions and the compound `_id` that was the
last accumulator failure.
Expressions are *compiled once per pipeline and evaluated per document*, and
that split is the point rather than an optimisation: it keeps the property M2's
refusals bought, which is that a pipeline that cannot be answered is refused
before a single document is read instead of half way through with part of the
work already reported. `Expr` is the compiled tree, `compile_expr` reports,
`eval_expr` cannot.
Nineteen operators: `$literal`, the five arithmetic ones, seven comparisons,
`$and`/`$or`/`$not`, `$cond` in both its forms, `$ifNull` and `$switch`. Plus
the two shapes that are not operators at all -- a compound document, which is
what a `$group` `_id` usually is, and an array.
Everything the corpus recorded, and none of it guessable:
- absent and a present null are *different* internally, because `$ifNull`
treats them alike and `$push` does not. Hence `?bson.Value` throughout,
where the obvious shortcut is to fold absent into `.null` at the boundary
and lose the distinction for good.
- arithmetic over absent or null is `null` -- not an error, not zero -- and
over a string is an error, 7157723.
- `$divide` by zero is 4848401, `$switch` with no branch and no default is
40069, and both are failures only a document can produce, so `EvalError`
exists and `report_eval_error` maps it.
- two operators in one expression document is 15983 and *not* `$group`'s
40238: mongod distinguishes an expression from an accumulator there.
- truthiness is MongoDB's, so `-5` is true and `0.0` is false.
- `$mod` follows the dividend's sign, so -5 mod 4 is -1.
- `$not` takes a bare argument as readily as a one-element array.
`compile_expr` and `compile_operator` call each other, so their error set is
written out rather than inferred -- Zig cannot infer a cycle, and the failure
mode is a "dependency loop" message that says nothing about expressions.
Three cases left the Tier 0 refusal test, because a compound `_id`, `$literal`
and a `$multiply` argument all work now. What is refused should be what is
missing, so an unknown operator and a wrong operand count took their place.
191/191 unit tests in ReleaseFast and ReleaseSafe, 83/83 fuzz, e2e 49, e2e2
concurrent, e2e3 16, e2e4 17, e2e6 72, e2e7 86, crud corpus unchanged at
201/90/196.
93 lines
3.7 KiB
Markdown
93 lines
3.7 KiB
Markdown
# The aggregation corpus
|
|
|
|
`mongodb/specifications` has no aggregation suite. The thirteen
|
|
`aggregate-*.json` files this project runs come from `crud` and test the
|
|
aggregate *command* — cursors, read concern, the write stages, collation,
|
|
`let`. They touch stages barely and expressions not at all: `$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
|
|
|
|
```sh
|
|
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
|
|
|
|
```sh
|
|
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 `$group` pipeline with a `$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. At the M2 tip it read 9 pass / 10 fail; with the
|
|
accumulators in:
|
|
|
|
```
|
|
group-accumulators.json 19 pass 0 fail 0 skip
|
|
expressions.json 27 pass 0 fail 0 skip
|
|
```
|
|
|
|
`group-accumulators` found its first real disagreement on the way to 18:
|
|
`$avg` over a group with no numeric value is `null`, not `0`, and a divisor
|
|
that counted documents rather than numbers would have passed every test
|
|
anybody would think to write by hand.
|
|
|
|
`expressions.json` was recorded before the evaluator was written and read
|
|
1 pass / 26 fail against it; it is green now. Expressions are exercised through
|
|
`$group`, because `_id` and the accumulator arguments are the only expression
|
|
positions that exist until `$addFields` and `$project`'s computed fields land.
|
|
|
|
What recording it settled, none of which is guessable:
|
|
|
|
| | mongod |
|
|
|---|---|
|
|
| `$add` over a missing field or null | `null`, not an error and not `0` |
|
|
| `$add` over a string | error 7157723 |
|
|
| `$divide` by zero | error 4848401 |
|
|
| `$mod` of -5 by 4 | `-1` — the dividend's sign |
|
|
| `$lt` of a number and a string | `true` — canonical type order |
|
|
| `$and` over `-5` | truthy |
|
|
| `$not` of a missing field | `true` |
|
|
| `$switch` with no branch and no default | error 40069 |
|
|
| two operators in one expression document | error 15983, *not* `$group`'s 40238 |
|
|
| `$subtract` with one operand | error 16020 |
|