Merge #17587: gui: show watch-only balance in send screen

4a96e459d733f1b6427221aaa1874ea00f79988a [gui] send: show watch-only balance in send screen (Sjors Provoost)
2689c8fd7159f47248c5fc365463be8b0e8b039c [test] qt: add send screen balance test (Sjors Provoost)

Pull request description:

  Now that we can create a PSBT from a watch-only wallet (#16944), we should also display the watch-only balance on the send screen.

  Before:
  <img width="1008" alt="before" src="https://user-images.githubusercontent.com/10217/69533384-030e9180-0f78-11ea-9748-c32c957e822e.png">

  After:
  <img width="1009" alt="Schermafbeelding 2019-11-26 om 11 44 17" src="https://user-images.githubusercontent.com/10217/69622879-19811f80-1042-11ea-8279-091012f39b38.png">

  I added a test to check the balance on the send screen, but it only covers regular wallets. A better would add a watch-only only wallet.

ACKs for top commit:
  meshcollider:
    utACK 4a96e459d733f1b6427221aaa1874ea00f79988a
  jb55:
    utACK 4a96e459d733f1b6427221aaa1874ea00f79988a
  promag:
    reACK 4a96e45, rebased and label change since last review.
  instagibbs:
    code review and light test ACK https://github.com/bitcoin/bitcoin/pull/17587/commits/4a96e459d733f1b6427221aaa1874ea00f79988a

Tree-SHA512: 4213549888bd309f72bdbba1453218f4a2b07e809100d786a3791897c75468f9092b06fe4b971942b1c228aa75ee7c04971f262ca9a478b42756e056eb534620

3 files changed, 17 insertions, 2 deletions

diff --git a/src/qt/forms/sendcoinsdialog.ui b/src/qt/forms/sendcoinsdialog.ui
index 7190d59240..cfd4bf33d4 100644
--- a/src/qt/forms/sendcoinsdialog.ui
+++ b/src/qt/forms/sendcoinsdialog.ui
@@ -1190,7 +1190,7 @@ Note:  Since the fee is calculated on a per-byte basis, a fee of "100 satoshis p
         <number>3</number>
        </property>
        <item>
-        <widget class="QLabel" name="label">
+        <widget class="QLabel" name="labelBalanceName">
          <property name="sizePolicy">
           <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
            <horstretch>0</horstretch>
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index 9c4c9dbb17..f1ea3e23e5 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -562,7 +562,12 @@ void SendCoinsDialog::setBalance(const interfaces::WalletBalances& balances)
 {
     if(model && model->getOptionsModel())
     {
-        ui->labelBalance->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), balances.balance));
+        CAmount balance = balances.balance;
+        if (model->privateKeysDisabled()) {
+            balance = balances.watch_only_balance;
+            ui->labelBalanceName->setText(tr("Watch-only balance:"));
+        }
+        ui->labelBalance->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), balance));
     }
 }
 
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index 980de711db..dfd56511ea 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -170,6 +170,16 @@ void TestGUI(interfaces::Node& node)
     sendCoinsDialog.setModel(&walletModel);
     transactionView.setModel(&walletModel);
 
+    {
+        // Check balance in send dialog
+        QLabel* balanceLabel = sendCoinsDialog.findChild<QLabel*>("labelBalance");
+        QString balanceText = balanceLabel->text();
+        int unit = walletModel.getOptionsModel()->getDisplayUnit();
+        CAmount balance = walletModel.wallet().getBalance();
+        QString balanceComparison = BitcoinUnits::formatWithUnit(unit, balance, false, BitcoinUnits::separatorAlways);
+        QCOMPARE(balanceText, balanceComparison);
+    }
+
     // Send two transactions, and verify they are added to transaction list.
     TransactionTableModel* transactionTableModel = walletModel.getTransactionTableModel();
     QCOMPARE(transactionTableModel->rowCount({}), 105);