Account data is not persisting for a really simple instruction

Question

I am calling an Anchor instruction (see below) from my tests to extend the lock date for this account.

Here is the Anchor code:

#[derive(Accounts)]
#[instruction(duration: u64)]
pub struct ExtendLock<'info> {
    #[account(mut)]
    pub owner: Signer<'info>,

    #[account(
        seeds = [
          lock.locker.as_ref(),
          owner.key().as_ref(),
          mint.key().as_ref()
        ],
        bump,
        has_one = mint,
        has_one = owner,
    )]
    pub lock: Account<'info, Lock>,

    pub mint: Account<'info, Mint>,

    pub system_program: Program<'info, System>,
}

pub fn extend_lock(ctx: Context<ExtendLock>, duration: u64) -> Result<()> {
    let lock = &mut ctx.accounts.lock;

    lock.unlock_date += duration;

    Ok(())
}

Notice the lock.unlock_date += duration...

Here is how I'm calling the instruction from my tests:

it("should extend a lock", async () => {
      const beforeDate = (
        await program.account.lock.fetch(env.user1Token1LockPDAKey)
      ).unlockDate.toNumber();
      
      console.log("-> ~ it ~ beforeDate:", beforeDate); // 1705041438
      
      const duration = new BN(60 * 60 * 24 * 30);
      const tx = await program.methods
        .extendLock(duration)
        .accounts({
          owner: env.user1.publicKey,
          lock: env.user1Token1LockPDAKey,
          mint: env.mint1Keypair.publicKey,
        })
        .signers([env.user1])
        .rpc();

      await provider.connection.confirmTransaction(tx);

      const afterDate = (
        await program.account.lock.fetch(env.user1Token1LockPDAKey)
      ).unlockDate.toNumber();

      console.log("-> ~ it ~ afterDate:", afterDate); // 1705041438
      
      expect(afterDate).to.equal(beforeDate + duration.toNumber());
    });

All of the accounts are correct and the test runs to completion, but the lock.unlock_date is the same. Code looks pretty straight forward to me, can someone point out what I'm doing wrong?

Answer 1

Add mut to pub lock: Account<'info, Lock>, to mark the account as writable:

    #[account(
        mut, //<--- add this
        seeds = [
          lock.locker.as_ref(),
          owner.key().as_ref(),
          mint.key().as_ref()
        ],
        bump,
        has_one = mint,
        has_one = owner,
    )]
    pub lock: Account<'info, Lock>,