Read and write keypair in jsonfile anchor solana

keypair_utils.ts

import * as fs from 'fs/promises';
import * as path from 'path';

const writeKeypairToFile = async (sk: Uint8Array, fileName: string): Promise<void> => {
  const filePath = path.join('tests/keys', `${fileName}.json`);

  try {
    await fs.writeFile(filePath, JSON.stringify(Array.from(sk)));
    console.log(`Keypair written to file: ${filePath}`);
  } catch (error) {
    console.error(`Error writing keypair to file: ${(error as Error).message}`);
  }
};

const readKeypairToFile = async (fileName: string): Promise<anchor.web3.Keypair | undefined> => {
  const filePath = path.join('tests/keys', `${fileName}.json`);

  try {
    const raw = await fs.readFile(filePath);
    const formattedData = JSON.parse(raw.toString());

    const keypair = anchor.web3.Keypair.fromSecretKey(Uint8Array.from(formattedData));
    console.log(keypair.publicKey.toString());
    return keypair

  } catch (error) {
    console.error(`Error reading keypair from file: ${(error as Error).message}`);
  }
};