Description
Pair caller image descriptions with decorative/informative contexts and missing-alt controls, retaining presence-check results without judging alternative-text quality.
An interface fixture makes content and state explicit so a consumer can test a rendering or interaction. Literal labels, modeled states, and calculated geometry remain separate from what a browser or assistive technology actually displays or announces.
Pair caller image descriptions with decorative/informative contexts and missing-alt controls, retaining presence-check results without judging alternative-text quality.
When to use this tool
Use this generator to create reproducible image alt context fixture cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.
How to use the tool and how it works
- Supply images, modes, count in the field shapes below. Set seed when you need an explicit replay.
- Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
- Read cases. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.
Draw an image context and baseline or missing-alt mode. Decorative entries use empty alt, other entries use supplied descriptions, and missing mode omits the attribute. Delegate presence checking and return escaped img markup.1
Delegated operations used for this result: img alt presence checker. Their calculation or parsing conventions apply to the corresponding result fields.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| images | Images | Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32. |
| images[].description | Description | Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128. |
| images[].context | Context | Required. Text; one of "decorative", "informative". |
| modes | Modes | Required. Array of Text; one of "contextual", "missing".; minimum items 1; maximum items 2. |
| count | Requested count; the mechanics explain whether one draw expands into several returned records. | Required. Safe integer; minimum 1; maximum 32. |
| seed | Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed. | Optional. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| cases | Cases | Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32. |
| cases[].description | Description | Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128. |
| cases[].context | Context | Required. Text; one of "decorative", "informative". |
| cases[].mode | Mode | Required. Text; one of "contextual", "missing". |
| cases[].alt | Alt | Required. Text; maximum UTF-16 length 256. or Null. |
| cases[].html | Html | Required. Text; maximum UTF-16 length 131072. |
| cases[].presence | Presence | Required. Object; no unknown keys. |
| cases[].presence.present | Present | Required. Boolean. |
| cases[].presence.emptyAlternative | Empty Alternative | Required. Boolean. |
| randomness | Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source. | Required. Object; no unknown keys. |
| randomness.seed | Optional numeric replay seed; normalization and precedence are explained below. | Required. Safe integer. or Null. |
| randomness.source | Source | Required. Text; one of "context", "seed". |
An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.
{
"input": {
"images": [
{
"description": "Campus map",
"context": "informative"
},
{
"description": "Divider",
"context": "decorative"
}
],
"modes": [
"contextual",
"missing"
],
"count": 2,
"seed": 42
},
"output": {
"cases": [
{
"description": "Divider",
"context": "decorative",
"mode": "contextual",
"alt": "",
"html": "<img alt=\"\">",
"presence": {
"present": true,
"emptyAlternative": true
}
},
{
"description": "Divider",
"context": "decorative",
"mode": "missing",
"alt": null,
"html": "<img>",
"presence": {
"present": false,
"emptyAlternative": false
}
}
],
"randomness": {
"seed": 42,
"source": "seed"
}
}
}Limitations and assumptions
- Presence is not quality: supplied descriptions are not evaluated for accuracy or context. Empty decorative alt differs from absent alt. No image is fetched and this is not a complete accessibility audit.
- A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
- The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.
Alternative or Complementary methods
For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.
References
Similar or alternative tools
- Random Heading Hierarchy Mutation Corpus Generator
Mutate caller heading sequences at a constructible interior position to introduce an upward skip, retaining baseline and mutated markup and the existing outline heuristic.
- Random Label Binding Mutation Corpus Generator
Construct supplied form-label markup with missing, wrong and nonlabelable duplicate-ID mutations, retaining lexical parsing and first-ID binding expectations without an accessibility verdict.