test,refactor(wallet): Move bump fee + foreign utxo tests

[ValuedMammal]

These files are added to wallet/tests directory

• add_foreign_utxo.rs
• build_fee_bump.rs
• common.rs

fixes bitcoindevkit/bdk_wallet#21

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• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

[aagbotemi]

Good job working on this PR @ValuedMammal

[tvpeter]

I suppose it will be easier to read if this tuple is named (sent_amount, received_amount)

[ValuedMammal]

I agree

[tvpeter]

I am curious about how the change output was handled. I can't see a test case or the method responsible for that.

[ValuedMammal]

If no change address is given, then the wallet looks for the next unused address from the change keychain

bdk/crates/wallet/src/wallet/mod.rs

Lines 1434 to 1438 in 5817ed0

	// get drain script
	let mut drain_index = Option::<(KeychainKind, u32)>::None;
	let drain_script = match params.drain_to {
	Some(ref drain_recipient) => drain_recipient.clone(),
	None => {

And the result of coin selection determines whether the change output is finally added.

bdk/crates/wallet/src/wallet/mod.rs

Lines 1511 to 1517 in 5817ed0

	// if there's change, create and add a change output
	if let Excess::Change { amount, .. } = excess {
	// create drain output
	let drain_output = TxOut {
	value: *amount,
	script_pubkey: drain_script,
	};

[tvpeter]

Thanks for working on this. I have learned a lot from this PR.

tACK 9ca1529

nit: I have left some comments. Thanks

[ValuedMammal]

@tvpeter thanks for reviewing. I agree with your suggestions, but since this is a refactor/ code move, it would be better in my opinion to not introduce logical changes and instead push those to a follow up PR.

[ValuedMammal]

Reopened bitcoindevkit/bdk_wallet#199