refactor!: add methods() to contract abigen

[hal3e]

closes: #515

• removed the Builder pattern from abigen
• added a new struct that holds the contract methods which is built by the contract instance

Now the workflow looks like this:

    abigen!(
        SimpleContract,
        "packages/fuels/tests/takes_ints_returns_bool-abi.json",
    );

    let wallet = launch_provider_and_get_wallet().await;

    // `SimpleContract` is the name of the contract
    let contract_instance = SimpleContract::new(null_contract_id(), wallet);

    let call_handler = contract_instance.methods().takes_ints_returns_bool(42);

In the tests where we have multiple contract calls, I have saved the methods in a new variable and called the methods directly. For example:

    let contract_methods = SimpleContract::new(null_contract_id(), wallet).methods();

    let call_handler = contract_methods.takes_nested_struct(nested_struct_from_tokens);

[hal3e]

While I was updating the harness tests I figured that I could also update some test that I did not update when I made the setup_test_contract! macro. At that time, I did not update them because they used some custom wallets and/or providers. But then I remembered that if I named the custom wallet shared_wallet and declare it before the macro, I can still use the macro with the None value. But now I do not like the name shared_wallet anymore 😄 (Initially, I put shared_wallet as it would be shared between macros but that is not the only use case). So I decided to rename shared_wallet to just wallet and now we can have custom wallets or providers and still use the macro. Here is an example:

    let config = WalletsConfig::new(Some(2), Some(1), Some(DEFAULT_COIN_AMOUNT));

    let mut wallets = launch_custom_provider_and_get_wallets(config, None).await;
    let wallet = wallets.pop().unwrap();
    let wallet_2 = wallets.pop().unwrap();

    setup_contract_test!(
        contract_instance,
        None,
        "packages/fuels/tests/test_projects/contract_test"
    );

Let me know what you think about this 😄

[Salka1988]

Nice! 👍

[segfault-magnet]

Love it.

[MujkicA]

Why do we need this and with_wallet? I understand that with_wallet returns a new instance, but having them both is confusing. We should at least rename them, although I am more for deleting one unless there is an explicit need for it.

[MujkicA]

Should this have a reference to the instance instead? What should the user expect to happen if they change the wallet of the instance with the above wallet() method.

[hal3e]

They must call methods() again. AFAIK rust will not allow to have a reference to a dropped wallet. As the new one would replace it.

[MujkicA]

This creates a pitfall. It's not evident that if you change the wallet, the methods are affected too.
Can we use a reference to the actual instance or add a warning to the docs?

[hal3e]

(I am writing this without trying it out). wallet() and with_wallet both create a new instance so I think the reference is again a no go. IMO documentation should be enough.
wallet() does not create a new instance. We have two options:

• Try to have a reference inside methods to the instance. (I do not know if this will make problems when wallet moves)
• Remove wallet() and contract_id() (you can always make a new instance)

I am leaning toward the second option. If you use with_wallet you create a new instance and have to call methods again..

For context, I copied the wallet() and contract_id() methods from the old builder.

[hal3e]

I implemented the second option.

[digorithm]

Super clean implementation; goodbye name conflicts! 🎉