Merge bitcoin/bitcoin#26699: wallet, gui: bugfix, getAvailableBalance skips selected coins

68eed5df8656bed1be6526b014e58d3123102b03 test,gui: add coverage for PSBT creation on legacy watch-only wallets (furszy)
306aab5bb471904faed325d9f3b38b7e891c7bbb test,gui: decouple widgets and model into a MiniGui struct (furszy)
2f76ac0383904123676f1b4eeba0f772a4c5cb5d test,gui: decouple chain and wallet initialization from test case (furszy)
cd98b717398f7b13ace91ea9efac9ce1e60b4d62 gui: 'getAvailableBalance', include watch only balance (furszy)
74eac3a82fc948467d5a15a5af420b36ce8eb04a test: add coverage for 'useAvailableBalance' functionality (furszy)
dc1cc1c35995dc09085b3d9270c445b7923fdb51 gui: bugfix, getAvailableBalance skips selected coins (furszy)

Pull request description:

  Fixes https://github.com/bitcoin-core/gui/issues/688 and https://github.com/bitcoin/bitcoin/issues/26687.

  First Issue Description (https://github.com/bitcoin-core/gui/issues/688):

  The previous behavior for `getAvailableBalance`, when the coin control had selected coins, was to return the sum of them. Instead, we are currently returning the wallet's available total balance minus the selected coins total amount.

  Reason:
  Missed to update the `GetAvailableBalance` function to include the coin control selected coins on #25685.

  Context:
  Since #25685 we skip the selected coins inside `AvailableCoins`, the reason is that there is no need to waste resources walking through the entire wallet's txes map just to get coins that could have gotten by just doing a simple `mapWallet.find`).

  Places Where This Generates Issues (only when the user manually select coins via coin control):
  1) The GUI balance check prior the transaction creation process.
  2) The GUI "useAvailableBalance" functionality.

  Note 1:
  As the GUI uses a balance cache since https://github.com/bitcoin-core/gui/pull/598, this issue does not affect the regular spending process. Only arises when the user manually select coins.

  Note 2:
  Added test coverage for the `useAvailableBalance` functionality.

  ----------------------------------

  Second Issue Description (https://github.com/bitcoin/bitcoin/issues/26687):

  As we are using a cached balance on `WalletModel::getAvailableBalance`,
  the function needs to include the watch-only available balance for wallets
  with private keys disabled.

ACKs for top commit:
  Sjors:
    tACK 68eed5df8656bed1be6526b014e58d3123102b03
  achow101:
    ACK 68eed5df8656bed1be6526b014e58d3123102b03
  theStack:
    ACK 68eed5df8656bed1be6526b014e58d3123102b03

Tree-SHA512: 674f3e050024dabda2ff4a04b9ed3750cf54a040527204c920e1e38bd3d7f5fd4d096e4fd08a0fea84ee6abb5070f022b5c0d450c58fd30202ef05ebfd7af6d3

9 files changed, 248 insertions, 70 deletions

diff --git a/src/bench/wallet_create_tx.cpp b/src/bench/wallet_create_tx.cpp
index 80d23d1e51..cb31421598 100644
--- a/src/bench/wallet_create_tx.cpp
+++ b/src/bench/wallet_create_tx.cpp
@@ -102,7 +102,7 @@ static void WalletCreateTx(benchmark::Bench& bench, const OutputType output_type
     }
 
     // Check available balance
-    auto bal = wallet::GetAvailableBalance(wallet); // Cache
+    auto bal = WITH_LOCK(wallet.cs_wallet, return wallet::AvailableCoins(wallet).GetTotalAmount()); // Cache
     assert(bal == 50 * COIN * (chain_size - COINBASE_MATURITY));
 
     wallet::CCoinControl coin_control;
@@ -161,7 +161,7 @@ static void AvailableCoins(benchmark::Bench& bench, const std::vector<OutputType
     }
 
     // Check available balance
-    auto bal = wallet::GetAvailableBalance(wallet); // Cache
+    auto bal = WITH_LOCK(wallet.cs_wallet, return wallet::AvailableCoins(wallet).GetTotalAmount()); // Cache
     assert(bal == 50 * COIN * (chain_size - COINBASE_MATURITY));
 
     bench.epochIterations(2).run([&] {
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index e3fa4058a6..48f7fb6ad1 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -403,7 +403,7 @@ void SendCoinsDialog::presentPSBT(PartiallySignedTransaction& psbtx)
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << psbtx;
     GUIUtil::setClipboard(EncodeBase64(ssTx.str()).c_str());
-    QMessageBox msgBox;
+    QMessageBox msgBox(this);
     //: Caption of "PSBT has been copied" messagebox
     msgBox.setText(tr("Unsigned Transaction", "PSBT copied"));
     msgBox.setInformativeText(tr("The PSBT has been copied to the clipboard. You can also save it."));
@@ -791,8 +791,13 @@ void SendCoinsDialog::useAvailableBalance(SendCoinsEntry* entry)
     // Include watch-only for wallets without private key
     m_coin_control->fAllowWatchOnly = model->wallet().privateKeysDisabled() && !model->wallet().hasExternalSigner();
 
+    // Same behavior as send: if we have selected coins, only obtain their available balance.
+    // Copy to avoid modifying the member's data.
+    CCoinControl coin_control = *m_coin_control;
+    coin_control.m_allow_other_inputs = !coin_control.HasSelected();
+
     // Calculate available amount to send.
-    CAmount amount = model->getAvailableBalance(m_coin_control.get());
+    CAmount amount = model->getAvailableBalance(&coin_control);
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry* e = qobject_cast<SendCoinsEntry*>(ui->entries->itemAt(i)->widget());
         if (e && !e->isHidden() && e != entry) {
diff --git a/src/qt/sendcoinsdialog.h b/src/qt/sendcoinsdialog.h
index 2fcdf5b32a..ac05cd98e5 100644
--- a/src/qt/sendcoinsdialog.h
+++ b/src/qt/sendcoinsdialog.h
@@ -49,6 +49,9 @@ public:
     void pasteEntry(const SendCoinsRecipient &rv);
     bool handlePaymentRequest(const SendCoinsRecipient &recipient);
 
+    // Only used for testing-purposes
+    wallet::CCoinControl* getCoinControl() { return m_coin_control.get(); }
+
 public Q_SLOTS:
     void clear();
     void reject() override;
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index be5bcbbd54..eb7bf33a32 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -5,6 +5,7 @@
 #include <qt/test/wallettests.h>
 #include <qt/test/util.h>
 
+#include <wallet/coincontrol.h>
 #include <interfaces/chain.h>
 #include <interfaces/node.h>
 #include <key_io.h>
@@ -34,6 +35,8 @@
 #include <QAction>
 #include <QApplication>
 #include <QCheckBox>
+#include <QClipboard>
+#include <QObject>
 #include <QPushButton>
 #include <QTimer>
 #include <QVBoxLayout>
@@ -46,6 +49,7 @@ using wallet::CWallet;
 using wallet::CreateMockWalletDatabase;
 using wallet::RemoveWallet;
 using wallet::WALLET_FLAG_DESCRIPTORS;
+using wallet::WALLET_FLAG_DISABLE_PRIVATE_KEYS;
 using wallet::WalletContext;
 using wallet::WalletDescriptor;
 using wallet::WalletRescanReserver;
@@ -53,14 +57,14 @@ using wallet::WalletRescanReserver;
 namespace
 {
 //! Press "Yes" or "Cancel" buttons in modal send confirmation dialog.
-void ConfirmSend(QString* text = nullptr, bool cancel = false)
+void ConfirmSend(QString* text = nullptr, QMessageBox::StandardButton confirm_type = QMessageBox::Yes)
 {
-    QTimer::singleShot(0, [text, cancel]() {
+    QTimer::singleShot(0, [text, confirm_type]() {
         for (QWidget* widget : QApplication::topLevelWidgets()) {
             if (widget->inherits("SendConfirmationDialog")) {
                 SendConfirmationDialog* dialog = qobject_cast<SendConfirmationDialog*>(widget);
                 if (text) *text = dialog->text();
-                QAbstractButton* button = dialog->button(cancel ? QMessageBox::Cancel : QMessageBox::Yes);
+                QAbstractButton* button = dialog->button(confirm_type);
                 button->setEnabled(true);
                 button->click();
             }
@@ -69,7 +73,8 @@ void ConfirmSend(QString* text = nullptr, bool cancel = false)
 }
 
 //! Send coins to address and return txid.
-uint256 SendCoins(CWallet& wallet, SendCoinsDialog& sendCoinsDialog, const CTxDestination& address, CAmount amount, bool rbf)
+uint256 SendCoins(CWallet& wallet, SendCoinsDialog& sendCoinsDialog, const CTxDestination& address, CAmount amount, bool rbf,
+                  QMessageBox::StandardButton confirm_type = QMessageBox::Yes)
 {
     QVBoxLayout* entries = sendCoinsDialog.findChild<QVBoxLayout*>("entries");
     SendCoinsEntry* entry = qobject_cast<SendCoinsEntry*>(entries->itemAt(0)->widget());
@@ -83,7 +88,7 @@ uint256 SendCoins(CWallet& wallet, SendCoinsDialog& sendCoinsDialog, const CTxDe
     boost::signals2::scoped_connection c(wallet.NotifyTransactionChanged.connect([&txid](const uint256& hash, ChangeType status) {
         if (status == CT_NEW) txid = hash;
     }));
-    ConfirmSend();
+    ConfirmSend(/*text=*/nullptr, confirm_type);
     bool invoked = QMetaObject::invokeMethod(&sendCoinsDialog, "sendButtonClicked", Q_ARG(bool, false));
     assert(invoked);
     return txid;
@@ -121,7 +126,7 @@ void BumpFee(TransactionView& view, const uint256& txid, bool expectDisabled, st
     action->setEnabled(true);
     QString text;
     if (expectError.empty()) {
-        ConfirmSend(&text, cancel);
+        ConfirmSend(&text, cancel ? QMessageBox::Cancel : QMessageBox::Yes);
     } else {
         ConfirmMessage(&text, 0ms);
     }
@@ -136,6 +141,119 @@ void CompareBalance(WalletModel& walletModel, CAmount expected_balance, QLabel*
     QCOMPARE(balance_label_to_check->text().trimmed(), balanceComparison);
 }
 
+// Verify the 'useAvailableBalance' functionality. With and without manually selected coins.
+// Case 1: No coin control selected coins.
+// 'useAvailableBalance' should fill the amount edit box with the total available balance
+// Case 2: With coin control selected coins.
+// 'useAvailableBalance' should fill the amount edit box with the sum of the selected coins values.
+void VerifyUseAvailableBalance(SendCoinsDialog& sendCoinsDialog, const WalletModel& walletModel)
+{
+    // Verify first entry amount and "useAvailableBalance" button
+    QVBoxLayout* entries = sendCoinsDialog.findChild<QVBoxLayout*>("entries");
+    QVERIFY(entries->count() == 1); // only one entry
+    SendCoinsEntry* send_entry = qobject_cast<SendCoinsEntry*>(entries->itemAt(0)->widget());
+    QVERIFY(send_entry->getValue().amount == 0);
+    // Now click "useAvailableBalance", check updated balance (the entire wallet balance should be set)
+    Q_EMIT send_entry->useAvailableBalance(send_entry);
+    QVERIFY(send_entry->getValue().amount == walletModel.getCachedBalance().balance);
+
+    // Now manually select two coins and click on "useAvailableBalance". Then check updated balance
+    // (only the sum of the selected coins should be set).
+    int COINS_TO_SELECT = 2;
+    auto coins = walletModel.wallet().listCoins();
+    CAmount sum_selected_coins = 0;
+    int selected = 0;
+    QVERIFY(coins.size() == 1); // context check, coins received only on one destination
+    for (const auto& [outpoint, tx_out] : coins.begin()->second) {
+        sendCoinsDialog.getCoinControl()->Select(outpoint);
+        sum_selected_coins += tx_out.txout.nValue;
+        if (++selected == COINS_TO_SELECT) break;
+    }
+    QVERIFY(selected == COINS_TO_SELECT);
+
+    // Now that we have 2 coins selected, "useAvailableBalance" should update the balance label only with
+    // the sum of them.
+    Q_EMIT send_entry->useAvailableBalance(send_entry);
+    QVERIFY(send_entry->getValue().amount == sum_selected_coins);
+}
+
+void SyncUpWallet(const std::shared_ptr<CWallet>& wallet, interfaces::Node& node)
+{
+    WalletRescanReserver reserver(*wallet);
+    reserver.reserve();
+    CWallet::ScanResult result = wallet->ScanForWalletTransactions(Params().GetConsensus().hashGenesisBlock, /*start_height=*/0, /*max_height=*/{}, reserver, /*fUpdate=*/true, /*save_progress=*/false);
+    QCOMPARE(result.status, CWallet::ScanResult::SUCCESS);
+    QCOMPARE(result.last_scanned_block, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));
+    QVERIFY(result.last_failed_block.IsNull());
+}
+
+std::shared_ptr<CWallet> SetupLegacyWatchOnlyWallet(interfaces::Node& node, TestChain100Setup& test)
+{
+    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(node.context()->chain.get(), "", CreateMockWalletDatabase());
+    wallet->LoadWallet();
+    {
+        LOCK(wallet->cs_wallet);
+        wallet->SetWalletFlag(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
+        wallet->SetupLegacyScriptPubKeyMan();
+        // Add watched key
+        CPubKey pubKey = test.coinbaseKey.GetPubKey();
+        bool import_keys = wallet->ImportPubKeys({pubKey.GetID()}, {{pubKey.GetID(), pubKey}} , /*key_origins=*/{}, /*add_keypool=*/false, /*internal=*/false, /*timestamp=*/1);
+        assert(import_keys);
+        wallet->SetLastBlockProcessed(105, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));
+    }
+    SyncUpWallet(wallet, node);
+    return wallet;
+}
+
+std::shared_ptr<CWallet> SetupDescriptorsWallet(interfaces::Node& node, TestChain100Setup& test)
+{
+    std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(node.context()->chain.get(), "", CreateMockWalletDatabase());
+    wallet->LoadWallet();
+    LOCK(wallet->cs_wallet);
+    wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
+    wallet->SetupDescriptorScriptPubKeyMans();
+
+    // Add the coinbase key
+    FlatSigningProvider provider;
+    std::string error;
+    std::unique_ptr<Descriptor> desc = Parse("combo(" + EncodeSecret(test.coinbaseKey) + ")", provider, error, /* require_checksum=*/ false);
+    assert(desc);
+    WalletDescriptor w_desc(std::move(desc), 0, 0, 1, 1);
+    if (!wallet->AddWalletDescriptor(w_desc, provider, "", false)) assert(false);
+    CTxDestination dest = GetDestinationForKey(test.coinbaseKey.GetPubKey(), wallet->m_default_address_type);
+    wallet->SetAddressBook(dest, "", "receive");
+    wallet->SetLastBlockProcessed(105, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));
+    SyncUpWallet(wallet, node);
+    wallet->SetBroadcastTransactions(true);
+    return wallet;
+}
+
+struct MiniGUI {
+public:
+    SendCoinsDialog sendCoinsDialog;
+    TransactionView transactionView;
+    OptionsModel optionsModel;
+    std::unique_ptr<ClientModel> clientModel;
+    std::unique_ptr<WalletModel> walletModel;
+
+    MiniGUI(interfaces::Node& node, const PlatformStyle* platformStyle) : sendCoinsDialog(platformStyle), transactionView(platformStyle), optionsModel(node) {
+        bilingual_str error;
+        QVERIFY(optionsModel.Init(error));
+        clientModel = std::make_unique<ClientModel>(node, &optionsModel);
+    }
+
+    void initModelForWallet(interfaces::Node& node, const std::shared_ptr<CWallet>& wallet, const PlatformStyle* platformStyle)
+    {
+        WalletContext& context = *node.walletLoader().context();
+        AddWallet(context, wallet);
+        walletModel = std::make_unique<WalletModel>(interfaces::MakeWallet(context, wallet), *clientModel, platformStyle);
+        RemoveWallet(context, wallet, /* load_on_start= */ std::nullopt);
+        sendCoinsDialog.setModel(walletModel.get());
+        transactionView.setModel(walletModel.get());
+    }
+
+};
+
 //! Simple qt wallet tests.
 //
 // Test widgets can be debugged interactively calling show() on them and
@@ -149,64 +267,24 @@ void CompareBalance(WalletModel& walletModel, CAmount expected_balance, QLabel*
 //     QT_QPA_PLATFORM=xcb     src/qt/test/test_bitcoin-qt  # Linux
 //     QT_QPA_PLATFORM=windows src/qt/test/test_bitcoin-qt  # Windows
 //     QT_QPA_PLATFORM=cocoa   src/qt/test/test_bitcoin-qt  # macOS
-void TestGUI(interfaces::Node& node)
+void TestGUI(interfaces::Node& node, const std::shared_ptr<CWallet>& wallet)
 {
-    // Set up wallet and chain with 105 blocks (5 mature blocks for spending).
-    TestChain100Setup test;
-    for (int i = 0; i < 5; ++i) {
-        test.CreateAndProcessBlock({}, GetScriptForRawPubKey(test.coinbaseKey.GetPubKey()));
-    }
-    auto wallet_loader = interfaces::MakeWalletLoader(*test.m_node.chain, *Assert(test.m_node.args));
-    test.m_node.wallet_loader = wallet_loader.get();
-    node.setContext(&test.m_node);
-    const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(node.context()->chain.get(), "", CreateMockWalletDatabase());
-    wallet->LoadWallet();
-    wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
-    {
-        LOCK(wallet->cs_wallet);
-        wallet->SetupDescriptorScriptPubKeyMans();
-
-        // Add the coinbase key
-        FlatSigningProvider provider;
-        std::string error;
-        std::unique_ptr<Descriptor> desc = Parse("combo(" + EncodeSecret(test.coinbaseKey) + ")", provider, error, /* require_checksum=*/ false);
-        assert(desc);
-        WalletDescriptor w_desc(std::move(desc), 0, 0, 1, 1);
-        if (!wallet->AddWalletDescriptor(w_desc, provider, "", false)) assert(false);
-        CTxDestination dest = GetDestinationForKey(test.coinbaseKey.GetPubKey(), wallet->m_default_address_type);
-        wallet->SetAddressBook(dest, "", "receive");
-        wallet->SetLastBlockProcessed(105, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));
-    }
-    {
-        WalletRescanReserver reserver(*wallet);
-        reserver.reserve();
-        CWallet::ScanResult result = wallet->ScanForWalletTransactions(Params().GetConsensus().hashGenesisBlock, /*start_height=*/0, /*max_height=*/{}, reserver, /*fUpdate=*/true, /*save_progress=*/false);
-        QCOMPARE(result.status, CWallet::ScanResult::SUCCESS);
-        QCOMPARE(result.last_scanned_block, WITH_LOCK(node.context()->chainman->GetMutex(), return node.context()->chainman->ActiveChain().Tip()->GetBlockHash()));
-        QVERIFY(result.last_failed_block.IsNull());
-    }
-    wallet->SetBroadcastTransactions(true);
-
     // Create widgets for sending coins and listing transactions.
     std::unique_ptr<const PlatformStyle> platformStyle(PlatformStyle::instantiate("other"));
-    SendCoinsDialog sendCoinsDialog(platformStyle.get());
-    TransactionView transactionView(platformStyle.get());
-    OptionsModel optionsModel(node);
-    bilingual_str error;
-    QVERIFY(optionsModel.Init(error));
-    ClientModel clientModel(node, &optionsModel);
-    WalletContext& context = *node.walletLoader().context();
-    AddWallet(context, wallet);
-    WalletModel walletModel(interfaces::MakeWallet(context, wallet), clientModel, platformStyle.get());
-    RemoveWallet(context, wallet, /* load_on_start= */ std::nullopt);
-    sendCoinsDialog.setModel(&walletModel);
-    transactionView.setModel(&walletModel);
+    MiniGUI mini_gui(node, platformStyle.get());
+    mini_gui.initModelForWallet(node, wallet, platformStyle.get());
+    WalletModel& walletModel = *mini_gui.walletModel;
+    SendCoinsDialog& sendCoinsDialog = mini_gui.sendCoinsDialog;
+    TransactionView& transactionView = mini_gui.transactionView;
 
     // Update walletModel cached balance which will trigger an update for the 'labelBalance' QLabel.
     walletModel.pollBalanceChanged();
     // Check balance in send dialog
     CompareBalance(walletModel, walletModel.wallet().getBalance(), sendCoinsDialog.findChild<QLabel*>("labelBalance"));
 
+    // Check 'UseAvailableBalance' functionality
+    VerifyUseAvailableBalance(sendCoinsDialog, walletModel);
+
     // Send two transactions, and verify they are added to transaction list.
     TransactionTableModel* transactionTableModel = walletModel.getTransactionTableModel();
     QCOMPARE(transactionTableModel->rowCount({}), 105);
@@ -313,6 +391,76 @@ void TestGUI(interfaces::Node& node)
     QCOMPARE(walletModel.wallet().getAddressReceiveRequests().size(), size_t{0});
 }
 
+void TestGUIWatchOnly(interfaces::Node& node, TestChain100Setup& test)
+{
+    const std::shared_ptr<CWallet>& wallet = SetupLegacyWatchOnlyWallet(node, test);
+
+    // Create widgets and init models
+    std::unique_ptr<const PlatformStyle> platformStyle(PlatformStyle::instantiate("other"));
+    MiniGUI mini_gui(node, platformStyle.get());
+    mini_gui.initModelForWallet(node, wallet, platformStyle.get());
+    WalletModel& walletModel = *mini_gui.walletModel;
+    SendCoinsDialog& sendCoinsDialog = mini_gui.sendCoinsDialog;
+
+    // Update walletModel cached balance which will trigger an update for the 'labelBalance' QLabel.
+    walletModel.pollBalanceChanged();
+    // Check balance in send dialog
+    CompareBalance(walletModel, walletModel.wallet().getBalances().watch_only_balance,
+                   sendCoinsDialog.findChild<QLabel*>("labelBalance"));
+
+    // Set change address
+    sendCoinsDialog.getCoinControl()->destChange = GetDestinationForKey(test.coinbaseKey.GetPubKey(), OutputType::LEGACY);
+
+    // Time to reject "save" PSBT dialog ('SendCoins' locks the main thread until the dialog receives the event).
+    QTimer timer;
+    timer.setInterval(500);
+    QObject::connect(&timer, &QTimer::timeout, [&](){
+        for (QWidget* widget : QApplication::topLevelWidgets()) {
+            if (widget->inherits("QMessageBox")) {
+                QMessageBox* dialog = qobject_cast<QMessageBox*>(widget);
+                QAbstractButton* button = dialog->button(QMessageBox::Discard);
+                button->setEnabled(true);
+                button->click();
+                timer.stop();
+                break;
+            }
+        }
+    });
+    timer.start(500);
+
+    // Send tx and verify PSBT copied to the clipboard.
+    SendCoins(*wallet.get(), sendCoinsDialog, PKHash(), 5 * COIN, /*rbf=*/false, QMessageBox::Save);
+    const std::string& psbt_string = QApplication::clipboard()->text().toStdString();
+    QVERIFY(!psbt_string.empty());
+
+    // Decode psbt
+    std::optional<std::vector<unsigned char>> decoded_psbt = DecodeBase64(psbt_string);
+    QVERIFY(decoded_psbt);
+    PartiallySignedTransaction psbt;
+    std::string err;
+    QVERIFY(DecodeRawPSBT(psbt, MakeByteSpan(*decoded_psbt), err));
+}
+
+void TestGUI(interfaces::Node& node)
+{
+    // Set up wallet and chain with 105 blocks (5 mature blocks for spending).
+    TestChain100Setup test;
+    for (int i = 0; i < 5; ++i) {
+        test.CreateAndProcessBlock({}, GetScriptForRawPubKey(test.coinbaseKey.GetPubKey()));
+    }
+    auto wallet_loader = interfaces::MakeWalletLoader(*test.m_node.chain, *Assert(test.m_node.args));
+    test.m_node.wallet_loader = wallet_loader.get();
+    node.setContext(&test.m_node);
+
+    // "Full" GUI tests, use descriptor wallet
+    const std::shared_ptr<CWallet>& desc_wallet = SetupDescriptorsWallet(node, test);
+    TestGUI(node, desc_wallet);
+
+    // Legacy watch-only wallet test
+    // Verify PSBT creation.
+    TestGUIWatchOnly(node, test);
+}
+
 } // namespace
 
 void WalletTests::walletTests()
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index 61172d1625..565b732bf0 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -613,5 +613,17 @@ uint256 WalletModel::getLastBlockProcessed() const
 
 CAmount WalletModel::getAvailableBalance(const CCoinControl* control)
 {
-    return control && control->HasSelected() ? wallet().getAvailableBalance(*control) : getCachedBalance().balance;
+    // No selected coins, return the cached balance
+    if (!control || !control->HasSelected()) {
+        const interfaces::WalletBalances& balances = getCachedBalance();
+        CAmount available_balance = balances.balance;
+        // if wallet private keys are disabled, this is a watch-only wallet
+        // so, let's include the watch-only balance.
+        if (balances.have_watch_only && m_wallet->privateKeysDisabled()) {
+            available_balance += balances.watch_only_balance;
+        }
+        return available_balance;
+    }
+    // Fetch balance from the wallet, taking into account the selected coins
+    return wallet().getAvailableBalance(*control);
 }
diff --git a/src/wallet/interfaces.cpp b/src/wallet/interfaces.cpp
index 1a76e46c54..df1eb19a33 100644
--- a/src/wallet/interfaces.cpp
+++ b/src/wallet/interfaces.cpp
@@ -18,6 +18,7 @@
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/ui_change_type.h>
+#include <wallet/coincontrol.h>
 #include <wallet/context.h>
 #include <wallet/feebumper.h>
 #include <wallet/fees.h>
@@ -403,7 +404,24 @@ public:
     CAmount getBalance() override { return GetBalance(*m_wallet).m_mine_trusted; }
     CAmount getAvailableBalance(const CCoinControl& coin_control) override
     {
-        return GetAvailableBalance(*m_wallet, &coin_control);
+        LOCK(m_wallet->cs_wallet);
+        CAmount total_amount = 0;
+        // Fetch selected coins total amount
+        if (coin_control.HasSelected()) {
+            FastRandomContext rng{};
+            CoinSelectionParams params(rng);
+            // Note: for now, swallow any error.
+            if (auto res = FetchSelectedInputs(*m_wallet, coin_control, params)) {
+                total_amount += res->total_amount;
+            }
+        }
+
+        // And fetch the wallet available coins
+        if (coin_control.m_allow_other_inputs) {
+            total_amount += AvailableCoins(*m_wallet, &coin_control).GetTotalAmount();
+        }
+
+        return total_amount;
     }
     isminetype txinIsMine(const CTxIn& txin) override
     {
diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index 4548d5f813..57f3785a3a 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -356,12 +356,6 @@ CoinsResult AvailableCoinsListUnspent(const CWallet& wallet, const CCoinControl*
     return AvailableCoins(wallet, coinControl, /*feerate=*/ std::nullopt, params);
 }
 
-CAmount GetAvailableBalance(const CWallet& wallet, const CCoinControl* coinControl)
-{
-    LOCK(wallet.cs_wallet);
-    return AvailableCoins(wallet, coinControl).GetTotalAmount();
-}
-
 const CTxOut& FindNonChangeParentOutput(const CWallet& wallet, const COutPoint& outpoint)
 {
     AssertLockHeld(wallet.cs_wallet);
diff --git a/src/wallet/spend.h b/src/wallet/spend.h
index 78c2c5f22b..cc9ccf3011 100644
--- a/src/wallet/spend.h
+++ b/src/wallet/spend.h
@@ -94,8 +94,6 @@ CoinsResult AvailableCoins(const CWallet& wallet,
  */
 CoinsResult AvailableCoinsListUnspent(const CWallet& wallet, const CCoinControl* coinControl = nullptr, CoinFilterParams params = {}) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet);
 
-CAmount GetAvailableBalance(const CWallet& wallet, const CCoinControl* coinControl = nullptr);
-
 /**
  * Find non-change parent output.
  */
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 2e95a14807..edcfaa24e5 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -581,7 +581,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoinsTest, ListCoinsTestingSetup)
     BOOST_CHECK_EQUAL(list.begin()->second.size(), 1U);
 
     // Check initial balance from one mature coinbase transaction.
-    BOOST_CHECK_EQUAL(50 * COIN, GetAvailableBalance(*wallet));
+    BOOST_CHECK_EQUAL(50 * COIN, WITH_LOCK(wallet->cs_wallet, return AvailableCoins(*wallet).GetTotalAmount()));
 
     // Add a transaction creating a change address, and confirm ListCoins still
     // returns the coin associated with the change address underneath the