---
title: "wasi-memory-tests — Mova code model"
description: "Mova code model of wasi-host/src/tests.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/wasi-host/src/tests.rs.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

This page as HTML: <https://groupants.elamur.ai/free/en/mova/wasi-host/src/tests.rs.groupant/>

# wasi-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

- **kind:** groupant
- **status:** partial source bound model
- **source:** [`wasi-host/src/tests.rs`](https://github.com/ElamurAI/mova-free/blob/main/wasi-host/src/tests.rs)
- **source SHA-256:** `74685e5440b3b7df…`
- **repository folder:** [`wasi-host/src/tests.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/wasi-host/src/tests.rs.groupant)
- **repository commit:** `48f2e6f74146`

> **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](#approximant) |
| **ast** | partial | `syntax.json` |
| **composition** | partial | [composition](#composition) |
| **cost** | symbolic source derived | [invariant](#invariant) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant](#invariant) |
| **tests** | executed bounded checks | [tests](#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](#behavior-complement) |
| `reverse_reconstruction` | reverse_reconstruction | partial source derived model | [reverse_reconstruction](#reverse-reconstruction) |
| `fixture_coordinates` | fixture_coordinates | partial source derived model | [fixture_coordinates](#fixture-coordinates) |
| `vfs_join` | vfs_join | partial source derived model | [vfs_join](#vfs-join) |
| `engine_scope` | engine_scope | partial source derived model | [engine_scope](#engine-scope) |
| `fault_witness` | fault_witness | partial source derived model | [fault_witness](#fault-witness) |

## Parts

- [wasi-test-fixtures](https://md.groupants.elamur.ai/free/en/mova/wasi-host/src/tests.rs.groupant/wasi-test-fixtures.groupant/)

## 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.