Balances: Configurable Number of Genesis Accounts with Specified Balances for Benchmarking

[runcomet]

Derived Dev Accounts

Resolves #6040

Description

Enables an arbitrary number of dev accounts at genesis from a derivation path, feature gated by runtime-benchmarks.

Notes

• In the absence of a derivation path(i.e. dev_accounts: (...., None) at genesis), the system defaults to the path //Sender/{}.

• One dev account is created by default with the derivation path //Sender/{}.

• Developer accounts are excluded from the total issuance of the token supply, ensuring they do not impact the overall balance at genesis.

[cla-bot-2021]

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[runcomet]

Balances of dev_accounts should not be included in the total issuance? @ggwpez

[runcomet]

Hello @michalkucharczyk @ggwpez please review 🤝

[michalkucharczyk]

I would use some default (//Sender/{}) here, if None is given in genesis config.

[runcomet]

this can be placed in a helper function

/// Generate dev account from derivation string.
#[cfg(feature = "runtime-benchmarks")]
pub fn derive_dev_account(
	num_accounts: u32,
	balance: T::Balance,
	derivation: &String,
) {

	// Ensure that the number of accounts is not zero
	assert!(num_accounts > 0, "num_accounts must be greater than zero");

	assert!(
		balance >= <T as Config<I>>::ExistentialDeposit::get(),
		"the balance of any account should always be at least the existential deposit.",
	);

	for index in 0..num_accounts {
		// Replace "{}" in the derivation string with the index.
		let derivation_string = derivation.replace("{}", &index.to_string());

		// Attempt to create the key pair from the derivation string with error handling.
		let pair: SrPair = Pair::from_string(&derivation_string, None)
			.expect(&format!("Failed to parse derivation string: {}", derivation_string));

		// Convert the public key to AccountId.
		let who = T::AccountId::decode(&mut &pair.public().encode()[..])
			.expect(&format!("Failed to decode public key from pair: {}", pair.public()));
				
		frame_system::Pallet::<T>::inc_providers(&who);
		// Insert the account into the store and ensure it succeeds.
		assert!(T::AccountStore::insert(
			&who,
			AccountData { free: balance, ..Default::default() }
		)
			.is_ok());
	}
}

[runcomet]

I should add that there are test environments in other pallets that use .default().build()

using Option<> route with a default //Sender/{} would require the defaults to have at least one dev_account in each occurence.

[runcomet]

Should be ready for another review @michalkucharczyk @ggwpez