solana-program-examples/basics/create-account/poseidon/tests/create_system_account.ts

import * as anchor from '@coral-xyz/anchor';
import { Keypair, SystemProgram } from '@solana/web3.js';
import { assert } from 'chai';
import type { CreateSystemAccountProgram } from '../target/types/create_system_account_program';

describe('Create a system account', () => {
  const provider = anchor.AnchorProvider.env();
  anchor.setProvider(provider);
  const wallet = provider.wallet as anchor.Wallet;
  const connection = provider.connection;
  const program = anchor.workspace.CreateSystemAccountProgram as anchor.Program<CreateSystemAccountProgram>;

  it('Create the account', async () => {
    // Generate the public key from the seed and the programId
    const [accountState, _] = anchor.web3.PublicKey.findProgramAddressSync([anchor.utils.bytes.utf8.encode('account')], program.programId);

    await program.methods
      .createSystemAccount()
      .accounts({
        owner: wallet.publicKey,
      })
      .rpc();

    // Minimum balance for rent exemption for new account
    const lamports = await connection.getMinimumBalanceForRentExemption(0);

    // Check that the account was created
    const accountInfo = await connection.getAccountInfo(accountState);
    assert.isNotNull(accountInfo, 'Account should be created');
    assert(accountInfo.lamports >= lamports, 'Account must have the minimum amount of lamports required for rent');
  });
});