Function signPermit

tests/helpers/FiatToken.ts:211–261

({
  client,
  wallet,
  permitAmount,
  spenderAddress,
  nonce,
  deadline = maxUint256,
  tokenAddress = USDC.address,
}: {
  client: PublicClient
  wallet: WalletClient
  permitAmount: bigint
  deadline?: bigint
  spenderAddress: Address
  nonce?: bigint
  tokenAddress?: Address
})

}

export async function signPermit({
  client,
  wallet,
  permitAmount,
  spenderAddress,
  nonce,
  deadline = maxUint256,
  tokenAddress = USDC.address,
}: {
  client: PublicClient
  wallet: WalletClient
  permitAmount: bigint
  deadline?: bigint
  spenderAddress: Address
  nonce?: bigint
  tokenAddress?: Address
}) {
  const token = getContract({
    client,
    address: tokenAddress,
    abi: [...eip2612Abi, ...erc20Abi],
  })

  const signature = await wallet.signTypedData({
    types: {
      Permit: [
        { name: 'owner', type: 'address' },
        { name: 'spender', type: 'address' },
        { name: 'value', type: 'uint256' },
        { name: 'nonce', type: 'uint256' },
        { name: 'deadline', type: 'uint256' },
      ],
    },
    primaryType: 'Permit',
    domain: {
      chainId: client.chain?.id,
      name: await token.read.name(),
      verifyingContract: token.address,
      version: await token.read.version(),
    },
    message: {
      owner: wallet.account.address,
      spender: spenderAddress,
      value: permitAmount,
      nonce: nonce ?? (await token.read.nonces([wallet.account.address])),
      deadline,
    },
  })

  return signature
}