Elamur Groupantswasi-memory-tests
The groupant beside wasi-host/src/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 |
| composition | partial | composition |
| cost | symbolic source derived | invariant |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | tests |
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 |
fixture_coordinates | fixture_coordinates | partial source derived model | fixture_coordinates |
vfs_join | vfs_join | partial source derived model | vfs_join |
engine_scope | engine_scope | partial source derived model | engine_scope |
fault_witness | fault_witness | partial source derived model | fault_witness |
Parts
Model text
descriptant
wasi-memory-tests
Nine bounded tests exercise private Ctx helpers with synthetic Vfs and byte memory; six legacy tests cover args/open/escape/readdir/time/limits, three wave31 tests add late faults, memory/poll/descriptors and tiny binary Host run. Helpers do not route every WASI linker export.
Epoch 2026-10-31
Prospective review recorded before edits. Source review found late output FAULT effects and weaker-than-capability rights metadata; these are modeled as current behavior rather than silently repaired. Only bounded new test blocks were added; production code remains unchanged. Actual finite results and exact restoration receipts live under $MOVA_DATA/runs/octopus-wave31-wasi-2026-10-31. No full mlab guest, frozen suite, GPU or corpus run. This node retains its scoped observations for future refinement.
approximant
Forward relation
Nine bounded tests exercise private Ctx helpers with synthetic Vfs and byte memory; six legacy tests cover args/open/escape/readdir/time/limits, three wave31 tests add late faults, memory/poll/descriptors and tiny binary Host run. Helpers do not route every WASI linker export.
Scope: wasi-memory-tests. State and transitions follow the authoritative source, including partial effects before errors. No executable approximate replacement is attached: categorical errno/effects and module execution lack a useful validated percentage metric; future numerical profiles may only use1/2/5/10% caps after domain/reference evidence.
invariant
Invariant and cost
Nine bounded tests exercise private Ctx helpers with synthetic Vfs and byte memory; six legacy tests cover args/open/escape/readdir/time/limits, three wave31 tests add late faults, memory/poll/descriptors and tiny binary Host run. Helpers do not route every WASI linker export.
The invariant is conditional on the admitted transition: A passing finite suite excludes the particular failed assertions in its named fixtures, not untested guest or resource behavior.
Cost: Fixed fixtures<=8192 bytes; finite Vfs tiny files, two tiny wasm bodies, no host filesystem/corpus.
No wall-time gain, universal resource bound or atomic rollback is inferred. External Vfs/wasmi/native-mlab work remains separately charged.
composition
Composition
Nine bounded tests exercise private Ctx helpers with synthetic Vfs and byte memory; six legacy tests cover args/open/escape/readdir/time/limits, three wave31 tests add late faults, memory/poll/descriptors and tiny binary Host run. Helpers do not route every WASI linker export.
Immediate fragments partition selected mechanisms; their byte ranges refer to this single source and reuse its syntax projection. Memory helper success is a precondition for ABI transport, not proof that all linker wrappers dispatch correctly. WASI path/read/write helpers call real Vfs; mlab remains an external reference. Remaining top-level definitions and test bodies stay covered only by the parent source model.
models
Typed model catalog
behavior_complement
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: A passing finite suite excludes the particular failed assertions in its named fixtures, not untested guest or resource behavior.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
reverse_reconstruction
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Passing assertions constrain observed fixtures only; many alternate implementations agree on these finite cases. Test names/output cannot reconstruct full state or show complete preview1 compliance.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
fixture_coordinates
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: open helper copies path at1000 and writes fd at900, requiring sufficiently large buffer; helper itself can panic on small memory.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
vfs_join
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: open/read/write tests call production Ctx methods which call real Vfs; read-only, EXCL, holes, append and limits observable.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
engine_scope
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Tiny engine fixture has no imports; verifies run outcome/fuel and unreachable, not generated guest ABI imports.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
fault_witness
Subject: wasi-host/src/tests.rs at SHA-256 74685e5440b3b7df7f40518395e62d6cd68a60e80ff71e87b772f020c80bec8d, scope wasi-memory-tests. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Late faults retain clock, stdout, created file and allocated descriptor; tests explicitly reject transactional overclaims.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
tests
Checks and limits
Named actual-source tests run twice per debug/release; exact commands and numeric statuses retained externally. Test success is finite evidence only.
Exact names: tests::args_and_prestat, tests::clock_is_virtual_and_random_is_seeded, tests::escape_and_absolute_paths_are_not_capable, tests::limits_reach_the_guest_as_errno, tests::open_read_seek_write, tests::readdir_with_small_buffer_and_cookies, tests::wave31_late_faults_keep_prior_effects, tests::wave31_memory_poll_and_descriptor_boundaries, tests::wave31_tiny_engine_outcomes.
Memory tests bypass linker ABI; tiny empty/unreachable guests exercise engine outcomes only. The CLI test uses isolated import/export/journal fixtures.
Five compiled production/helper-source controls: append offset, virtual clock advance, trap status, CLI export gate and newest-mtime max. Each compiles, fails its selected assertion, restores exact original bytes and passes again. These controls cover their target relations, not every node. No assertion-only mutants. See external source-test-map.json, native-commands.json, verify.rs and numeric/raw receipts in $MOVA_DATA/runs/octopus-wave31-wasi-2026-10-31. The example main and frozen mlab paths are never executed.
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