Elamur Groupantsalgorithm-quickselect-tests
The groupant beside algorithms/src/quickselect/tests.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | syntax.json |
| descriptant | present | descriptant |
| invariant | partial | approximant |
| tests | existing checks referenced | checks |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
independent_oracle | independent_oracle | partial source derived model | independent_oracle |
property_assumptions | property_assumptions | partial source derived model | property_assumptions |
bounded_coverage_cost | bounded_coverage_cost | partial source derived model | bounded_coverage_cost |
Model text
descriptant
quickselect tests groupant
Epoch 2026-10-29: prospective predictions saved outside repository before implementation. Original std-only code/fixtures; four algorithm tests pass twice. Compiled red control: reverse strict partition comparison.
Combiner: source identity, recurrence, invariant and checks constrain a conditional model. Complement and converse answer different questions; no additive inverse identity. Syntax is partial with opaque macros and no type or name resolution. Finite evidence is not proof of all inputs or parent wiring. Lawful Ord and successful execution are assumed; trait panics and allocation failures are outside successful-call semantics. Preserve these observations in future epochs. No runtime speedup claim.
approximant
Forward, invariant and cost
Generate bounded fixtures, compute independent references, assert agreement and separate structural properties. References do not consult production outputs. Compare every rank with fully sorted copy; separately assert partition and multiset.
Assumptions: Invalid rank preserves exact input; valid prefix<=selected<=suffix; lawful Reverse wrapper.
Coverage: 3280 ternary arrays length 0..7, 24604 rank attempts including invalid endpoints; seeded 516 full-width entries and sorted/reverse/equal vectors. Test oracle costs are described in models.md; production cost: O(n²) worst time, O(1) auxiliary space; invalid rank O(1).
models
quickselect test models
Subject/revision: tests.rs at manifest SHA. Observe one test invocation under lawful Ord and ordinary allocation. Partial source-derived models have bounded evidence; no universal proof or arbitrary panic behavior is modeled.
behavior_complement
U=(fixture, candidate result, verdict). Pass with violated oracle equality or explicit property assertion is absent from the assertion graph. This exact complement slice does not exclude implementations overfit to tested fixtures. The compiled mutation (reverse strict partition comparison) is rejected by one exact filtered test.
reverse_reconstruction
Passing fixtures constrain implementation outputs/properties only on this finite domain; all agreeing functions remain compatible. Failure identifies a counterexample, not a unique bug or source. The mutant is one member of a failure fiber. Complete source reconstruction is not implemented.
independent_oracle
Compare every rank with fully sorted copy; separately assert partition and multiset. Independent control flow can still share contract misunderstandings; bounded correspondence is evidence rather than a proof of all inputs.
property_assumptions
Invalid rank preserves exact input; valid prefix<=selected<=suffix; lawful Reverse wrapper. Dropping lawful order or changing strictness invalidates these targets. Witnesses and custom-order tests exercise only the declared bounded projection.
bounded_coverage_cost
3280 ternary arrays length 0..7, 24604 rank attempts including invalid endpoints; seeded 516 full-width entries and sorted/reverse/equal vectors. Seeds use wrapping arithmetic. Generation is exponential in a fixed small bound. Reference vectors add O(n) space; reference sorting work is separate from the algorithm under test. Production cost: O(n²) worst time, O(1) auxiliary space; invalid rank O(1).
checks
Evidence, 2026-10-29
Four tests for this algorithm passed twice with temporary local crate exports: 66 total tests, identical normalized outcomes. Strict all-target Clippy and rustfmt passed. Temporary exports are not committed.
Coverage: 3280 ternary arrays length 0..7, 24604 rank attempts including invalid endpoints; seeded 516 full-width entries and sorted/reverse/equal vectors.
External mutant (reverse strict partition comparison) compiled; exactly one filtered new exhaustive test failed an assertion with exit 101. No mutant committed. One red control is not mutation completeness. Parent owns final exports, registry and source bindings.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/algorithms/src/quickselect/tests.rs.groupant/