Random Drag and Drop Item State Fixture Generator

Description

Generate atomic move attempts across supplied containers, checking capacities and item eligibility and retaining explicit rejected moves and inventory snapshots.

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.

Generate atomic move attempts across supplied containers, checking capacities and item eligibility and retaining explicit rejected moves and inventory snapshots.

When to use this tool

Use this generator to create reproducible drag drop item state 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 items, containers, moveCount 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 initial, events, final. Use the conventions below. Keep answer-bearing fields separate when presenting an exercise.

Validate initial placements against eligible containers and capacities. Sample item/target moves, accepting only a different eligible container with spare capacity, and return explicit same-container, ineligible, capacity, or accepted reasons with snapshots.^[1]

Input field	Meaning and units	Accepted input
items	Items	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
items[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
items[].label	Supplied display label.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128.
items[].containerId	Container Id	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
items[].eligibleContainerIds	Eligible Container Ids	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 1; maximum items 16.
containers	Containers	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
containers[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
containers[].capacity	Capacity	Required. Safe integer; minimum 0; maximum 16.
moveCount	Move Count	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
initial	Initial	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
initial[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
initial[].itemIds	Item Ids	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 0; maximum items 16.
events	Events	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32.
events[].itemId	Item Id	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
events[].label	Supplied display label.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128.
events[].sourceId	Source Id	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
events[].targetId	Target Id	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
events[].accepted	Accepted	Required. Boolean.
events[].reason	Reason	Required. Text; maximum UTF-16 length 256.
events[].containers	Containers	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
events[].containers[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
events[].containers[].itemIds	Item Ids	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 0; maximum items 16.
final	Final	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
final[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
final[].itemIds	Item Ids	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 0; maximum items 16.
randomness	Replay source and normalized 32-bit seed, or null seed for an advancing context source.	Required. Object; no unknown keys.
randomness.seed	Optional safe-integer 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.

json

{
  "input": {
    "items": [
      {
        "id": "a",
        "label": "Alpha",
        "containerId": "left",
        "eligibleContainerIds": [
          "left",
          "right"
        ]
      },
      {
        "id": "b",
        "label": "Beta",
        "containerId": "right",
        "eligibleContainerIds": [
          "left",
          "right"
        ]
      }
    ],
    "containers": [
      {
        "id": "left",
        "capacity": 1
      },
      {
        "id": "right",
        "capacity": 1
      }
    ],
    "moveCount": 2,
    "seed": 42
  },
  "output": {
    "initial": [
      {
        "id": "left",
        "itemIds": [
          "a"
        ]
      },
      {
        "id": "right",
        "itemIds": [
          "b"
        ]
      }
    ],
    "events": [
      {
        "itemId": "b",
        "label": "Beta",
        "sourceId": "right",
        "targetId": "left",
        "accepted": false,
        "reason": "capacity",
        "containers": [
          {
            "id": "left",
            "itemIds": [
              "a"
            ]
          },
          {
            "id": "right",
            "itemIds": [
              "b"
            ]
          }
        ]
      },
      {
        "itemId": "b",
        "label": "Beta",
        "sourceId": "right",
        "targetId": "right",
        "accepted": false,
        "reason": "same-container",
        "containers": [
          {
            "id": "left",
            "itemIds": [
              "a"
            ]
          },
          {
            "id": "right",
            "itemIds": [
              "b"
            ]
          }
        ]
      }
    ],
    "final": [
      {
        "id": "left",
        "itemIds": [
          "a"
        ]
      },
      {
        "id": "right",
        "itemIds": [
          "b"
        ]
      }
    ],
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

Rejected moves leave state unchanged. Snapshots list items in source order, not a user-reordered list. The tool does not implement drag interaction, keyboard alternatives, focus behavior, or persistence.
A replay requires the same complete input and implementation. The stated sampling convention applies within its eligible space. A finite draw does not exhaust all possible outputs; repeats remain possible unless a distinct-selection rule is explicit.
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

Tool behavior and example: Random Drag and Drop Item State Fixture Generator — tool.io

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