test: GUI WalletTests, trigger walletModel balance changed manually.

So the model updates its internal state and can be used by the widgets.

Plus unify balance check code in the test.

src/qt/test/wallettests.cpp

@@ -129,6 +129,13 @@ void BumpFee(TransactionView& view, const uint256& txid, bool expectDisabled, st
     QVERIFY(text.indexOf(QString::fromStdString(expectError)) != -1);
 }
 
+void CompareBalance(WalletModel& walletModel, CAmount expected_balance, QLabel* balance_label_to_check)
+{
+    BitcoinUnit unit = walletModel.getOptionsModel()->getDisplayUnit();
+    QString balanceComparison = BitcoinUnits::formatWithUnit(unit, expected_balance, false, BitcoinUnits::SeparatorStyle::ALWAYS);
+    QCOMPARE(balance_label_to_check->text().trimmed(), balanceComparison);
+}
+
 //! Simple qt wallet tests.
 //
 // Test widgets can be debugged interactively calling show() on them and
@@ -193,15 +200,10 @@ 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();
-        BitcoinUnit unit = walletModel.getOptionsModel()->getDisplayUnit();
-        CAmount balance = walletModel.wallet().getBalance();
-        QString balanceComparison = BitcoinUnits::formatWithUnit(unit, balance, false, BitcoinUnits::SeparatorStyle::ALWAYS);
-        QCOMPARE(balanceText, balanceComparison);
-    }
+    // 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"));
 
     // Send two transactions, and verify they are added to transaction list.
     TransactionTableModel* transactionTableModel = walletModel.getTransactionTableModel();
@@ -221,12 +223,8 @@ void TestGUI(interfaces::Node& node)
     // Check current balance on OverviewPage
     OverviewPage overviewPage(platformStyle.get());
     overviewPage.setWalletModel(&walletModel);
-    QLabel* balanceLabel = overviewPage.findChild<QLabel*>("labelBalance");
-    QString balanceText = balanceLabel->text().trimmed();
-    BitcoinUnit unit = walletModel.getOptionsModel()->getDisplayUnit();
-    CAmount balance = walletModel.wallet().getBalance();
-    QString balanceComparison = BitcoinUnits::formatWithUnit(unit, balance, false, BitcoinUnits::SeparatorStyle::ALWAYS);
-    QCOMPARE(balanceText, balanceComparison);
+    walletModel.pollBalanceChanged(); // Manual balance polling update
+    CompareBalance(walletModel, walletModel.wallet().getBalance(), overviewPage.findChild<QLabel*>("labelBalance"));
 
     // Check Request Payment button
     ReceiveCoinsDialog receiveCoinsDialog(platformStyle.get());