test: add tests for more advanced txbuilder operations

bdk-swift/Tests/BitcoinDevKitTests/LiveTxBuilderTests.swift

@@ -31,4 +31,47 @@ final class LiveTxBuilderTests: XCTestCase {
         print(psbt.serialize())
         XCTAssertTrue(psbt.serialize().hasPrefix("cHNi"), "PSBT should start with cHNI")
     }
+
+    func testComplexTxBuilder() throws {
+        let descriptor = try Descriptor(
+            descriptor: "wpkh(tprv8ZgxMBicQKsPf2qfrEygW6fdYseJDDrVnDv26PH5BHdvSuG6ecCbHqLVof9yZcMoM31z9ur3tTYbSnr1WBqbGX97CbXcmp5H6qeMpyvx35B/84h/1h/0h/0/*)",
+            network: Network.testnet
+        )
+        let changeDescriptor = try Descriptor(
+            descriptor: "wpkh(tprv8ZgxMBicQKsPf2qfrEygW6fdYseJDDrVnDv26PH5BHdvSuG6ecCbHqLVof9yZcMoM31z9ur3tTYbSnr1WBqbGX97CbXcmp5H6qeMpyvx35B/84h/1h/0h/1/*)",
+            network: Network.testnet
+        )
+        let wallet = try Wallet.newNoPersist(
+            descriptor: descriptor,
+            changeDescriptor: changeDescriptor,
+            network: .testnet
+        )
+        let esploraClient = EsploraClient(url: "https://mempool.space/testnet/api")
+        let update = try esploraClient.scan(
+            wallet: wallet,
+            stopGap: 10,
+            parallelRequests: 1
+        )
+        try wallet.applyUpdate(update: update)
+
+        XCTAssertGreaterThan(wallet.getBalance().total, UInt64(0), "Wallet must have positive balance, please add funds")
+
+        let recipient1: Address = try Address(address: "tb1qrnfslnrve9uncz9pzpvf83k3ukz22ljgees989", network: .testnet)
+        let recipient2: Address = try Address(address: "tb1qw2c3lxufxqe2x9s4rdzh65tpf4d7fssjgh8nv6", network: .testnet)
+        let allRecipients: [ScriptAmount] = [
+            ScriptAmount(script: recipient1.scriptPubkey(), amount: 4200),
+            ScriptAmount(script: recipient2.scriptPubkey(), amount: 4200)
+        ]
+
+        let psbt: PartiallySignedTransaction = try TxBuilder()
+            .setRecipients(recipients: allRecipients)
+            .feeRate(satPerVbyte: 4.0)
+            .changePolicy(changePolicy: ChangeSpendPolicy.changeForbidden)
+            .enableRbf()
+            .finish(wallet: wallet)
+
+        try! wallet.sign(psbt: psbt)
+
+        XCTAssertTrue(psbt.serialize().hasPrefix("cHNi"), "PSBT should start with cHNI")
+    }
 }