FuelLabs/fuels-ts · warning · FuelError

INVALID_INPUT_PARAMETERS

INVALID_INPUT_PARAMETERS

Error message

Number of wallets must be greater than zero.

What it means

Thrown by `WalletsConfig.validate()` (test-utils) when the `count` (wallets) option is an empty array or a number <= 0. The test wallet launcher needs at least one wallet to seed, so it rejects a non-positive count before generating any test fixtures.

Source

Thrown at packages/account/src/test-utils/wallet-config.ts:151

            });
          }
        });
      });

    return coins;
  }

  private static validate({
    count: wallets,
    assets,
    coinsPerAsset,
    amountPerCoin,
  }: WalletsConfigOptions) {
    if (
      (Array.isArray(wallets) && wallets.length === 0) ||
      (typeof wallets === 'number' && wallets <= 0)
    ) {
      throw new FuelError(
        FuelError.CODES.INVALID_INPUT_PARAMETERS,
        'Number of wallets must be greater than zero.'
      );
    }
    if (
      (Array.isArray(assets) && assets.length === 0) ||
      (typeof assets === 'number' && assets <= 0)
    ) {
      throw new FuelError(
        FuelError.CODES.INVALID_INPUT_PARAMETERS,
        'Number of assets per wallet must be greater than zero.'
      );
    }
    if (coinsPerAsset <= 0) {
      throw new FuelError(
        FuelError.CODES.INVALID_INPUT_PARAMETERS,
        'Number of coins per asset must be greater than zero.'
      );

View on GitHub (pinned to b3f37c91ac)

Solutions

  1. Set `wallets` to a positive number or a non-empty array in your WalletsConfig.
  2. Guard the caller to skip setup entirely when the computed count is 0.
  3. Add an assertion in your test bootstrap before launching the node.

Example fix

// before
await launchTestNode({ walletsConfig: { count: 0, coinsPerAsset: 1, amountPerCoin: 100 } });
// after
await launchTestNode({ walletsConfig: { count: 2, coinsPerAsset: 1, amountPerCoin: 100 } });
Defensive patterns

Strategy: validation

Validate before calling

function walletCount(v: number | unknown[]): number { return Array.isArray(v) ? v.length : v; }
if (walletCount(config.count) <= 0) throw new Error('wallets must be > 0');

Type guard

null

Try / catch

null

Prevention

When it happens

Trigger: Calling `launchTestNode` (or directly constructing a `WalletsConfig`) with `wallets: 0`, `wallets: -1`, or `wallets: []`. The validate check at wallet-config.ts:147 fires.

Common situations: Parameterizing a test setup from a config where the wallet count defaulted to 0; refactoring a test suite and forgetting to set the count; dynamically computing wallet count from a list that came back empty.

Related errors

AI-assisted analysis of FuelLabs/fuels-ts@b3f37c91ac (2026-08-12). Data as JSON: /api/errors/68ac9c0b1c562525. Report an issue: GitHub.