Elamur Groupantsalgorithm-run-length-encoding-tests
The groupant beside algorithms/src/run_length_encoding/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 | bounded checked | Forward |
| ast | partial | syntax.json |
| cost | symbolic unmeasured | Cost |
| descriptant | present | descriptant |
| invariant | source derived | Invariant |
| tests | bounded executed | evidence |
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 |
|---|---|---|---|
nonbehavior | behavior_complement | partial source derived | nonbehavior |
preimages | reverse_reconstruction | partial source derived | preimages |
oracle-independence | refinement_relation | partial source derived | oracle-independence |
mutation-sensitivity | counterfactual_relation | partial source derived | mutation-sensitivity |
repeatability | metamorphic_relation | partial source derived | repeatability |
Model text
descriptant
algorithm-run-length-encoding-tests
Prospective model saved before implementation in $MOVA_DATA/runs/octopus-wave18-strings-2026-10-30/prospective.md.
Run bounded independent oracle fixtures, edge witnesses, and executable reconstruction invariants; assertions certify only the exercised inputs.
All oracle cases are generated deterministically; comparison or reconstruction must assert, not merely execute.
Observed 2026-10-30: 9,841 ternary words through length 8 checked for roundtrip, transition-count canonicality and exact total lengths. Every byte and a 10,000-byte run checked. Zero, adjacent equal, usize overflow, budget and capacity errors checked. Mutation increments a run count by two; exhaustive_canonical_roundtrips fails.
Partial Rust syntax projection excludes macro expansion and semantic resolution. Finite tests do not prove general correctness or linear cost. No executable approximation profile: outputs are discrete exact objects and no useful certified surrogate metric is proposed.
model
algorithm-run-length-encoding-tests
Forward
Run bounded independent oracle fixtures, edge witnesses, and executable reconstruction invariants; assertions certify only the exercised inputs.
Invariant
All oracle cases are generated deterministically; comparison or reconstruction must assert, not merely execute.
Cost
Finite exponential small-input oracle enumeration is intentional; production cost is modeled separately. Test allocation is ordinary and unbudgeted.
nonbehavior
Passing fixtures do not establish universal correctness, asymptotic complexity, allocator exhaustion behavior or Unicode semantics. A compiler failure does not count as a killed mutation.
Domain: finite byte inputs and stated successful-allocation/representability premises. Observation: public call or named internal state. Status: source-derived exact target relation with bounded evidence, not a general proof.
preimages
A named assertion failure identifies a violated fixture relation but may have many implementation causes. Passing observations retain all implementations agreeing on the enumerated finite domain.
Domain: finite byte inputs and stated successful-allocation/representability premises. Observation: public call or named internal state. Status: source-derived exact target relation with bounded evidence, not a general proof.
oracle-independence
9,841 ternary words through length 8 checked for roundtrip, transition-count canonicality and exact total lengths. Every byte and a 10,000-byte run checked. Zero, adjacent equal, usize overflow, budget and capacity errors checked. Mutation increments a run count by two; exhaustive_canonical_roundtrips fails.
Domain: finite byte inputs and stated successful-allocation/representability premises. Observation: public call or named internal state. Status: source-derived exact target relation with bounded evidence, not a general proof.
mutation-sensitivity
The compiled intentional production mutation must reach its named assertion and fail; exact production bytes are restored and the positive suite reruns.
Domain: finite byte inputs and stated successful-allocation/representability premises. Observation: public call or named internal state. Status: source-derived exact target relation with bounded evidence, not a general proof.
repeatability
Two serial debug runs and two serial optimized runs must have identical normalized test identities and outcomes. Timing fields are excluded; no speed claim follows.
Domain: finite byte inputs and stated successful-allocation/representability premises. Observation: public call or named internal state. Status: source-derived exact target relation with bounded evidence, not a general proof.
evidence
Evidence, 2026-10-30
Source SHA-256: bf2bebfd9c291d5415f32b8e36bebb56bc5494288b84721ba2947655fc16e066.
Three tests for this algorithm passed twice in debug and twice with rustc -O, serial execution and identical normalized identities. Compiled mutation failed the named assertion; source restored byte exactly and positive suite passed again. Two source-bound partial syntax projections were byte identical.
9,841 ternary words through length 8 checked for roundtrip, transition-count canonicality and exact total lengths. Every byte and a 10,000-byte run checked. Zero, adjacent equal, usize overflow, budget and capacity errors checked. Mutation increments a run count by two; exhaustive_canonical_roundtrips fails.
Logs under $MOVA_DATA/runs/octopus-wave18-strings-2026-10-30:
- run_length_encoding-debug-1.log: 48211eecae569f5c4f0b5b6b05d645b19ff145c359cf1ab3ac80c450f7788887
- run_length_encoding-debug-2.log: 48211eecae569f5c4f0b5b6b05d645b19ff145c359cf1ab3ac80c450f7788887
- run_length_encoding-release-1.log: 86fa04f7f772160ec25c896cff78fb89fd34717424ddca73fac7bb5ce5cc2ca4
- run_length_encoding-release-2.log: 86fa04f7f772160ec25c896cff78fb89fd34717424ddca73fac7bb5ce5cc2ca4
- run_length_encoding-mutant.log: 1e9116050511572e86c1307f5bc7e6c0b1173e236e01e7257f6991911bb18b5b
- run_length_encoding-restored.log: 48211eecae569f5c4f0b5b6b05d645b19ff145c359cf1ab3ac80c450f7788887
- cargo-run_length_encoding-debug-1.log: 95ab64b766d891e271f1620e86f5d57400af36e67d92c54e0b17d14a62f20618
- cargo-run_length_encoding-debug-2.log: ca418df8875f4248ba22455550a81126f70c15e66bb84d53b0a43d155ee0c027
- cargo-run_length_encoding-release-1.log: 47a578747c1a354b9ca9be32f8a1ca72d1e4857174f8d591458489c24f3454f5
- cargo-run_length_encoding-release-2.log: 47a578747c1a354b9ca9be32f8a1ca72d1e4857174f8d591458489c24f3454f5
Cargo focused suites also passed twice in debug and twice in release with matching normalized outcomes. Strict library Clippy passed. Temporary exports restored. Clippy log SHA-256: a5668d2636de8c7e7c3d3a1b6aea1da32174b64bee750b6b6cdfca8afc01a77b.
Partial Rust syntax projection excludes macro expansion and semantic resolution. Finite tests do not prove general correctness or linear cost. No executable approximation profile: outputs are discrete exact objects and no useful certified surrogate metric is proposed.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/algorithms/src/run_length_encoding/tests.rs.groupant/