GUI: use cached balance in overviewpage and sendcoinsdialog

Plus, calculate the cached balance right when the wallet model, so the wallet widgets don't need to redo the same balance calculation multiple times when they are waiting for the model balance polling timer.

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

test wise: `WalletTests` now need to trigger the walletModel balance changed manually. So the model updates its internal state and can be used by the widgets.

This is because the test does not start the balance polling timer, in the same way as does not initialize several parts of the GUI workflow. All the objects (wallet, models, views, etc) that are used on this test are manually created instead of using the `WalletController` class flow.

Rationale is that this unit test is focused on verifying the GUI widgets/views behavior only: update the presented information, etc. when they receive different signals and/or function calls from outside (in other words, focus is on the signal slots/receiver side). It's not about whether the wallet balance polling timer is functioning as expected or not (which we definitely create a new test case for it in a follow-up work).

1 files changed, 3 insertions, 4 deletions

diff --git a/src/qt/overviewpage.cpp b/src/qt/overviewpage.cpp
index 820bcbf3cd..900985a108 100644
--- a/src/qt/overviewpage.cpp
+++ b/src/qt/overviewpage.cpp
@@ -277,14 +277,13 @@ void OverviewPage::setWalletModel(WalletModel *model)
         ui->listTransactions->setModelColumn(TransactionTableModel::ToAddress);
 
         // Keep up to date with wallet
-        interfaces::Wallet& wallet = model->wallet();
-        interfaces::WalletBalances balances = wallet.getBalances();
-        setBalance(balances);
+        setBalance(model->getCachedBalance());
         connect(model, &WalletModel::balanceChanged, this, &OverviewPage::setBalance);
 
         connect(model->getOptionsModel(), &OptionsModel::displayUnitChanged, this, &OverviewPage::updateDisplayUnit);
 
-        updateWatchOnlyLabels(wallet.haveWatchOnly() && !model->wallet().privateKeysDisabled());
+        interfaces::Wallet& wallet = model->wallet();
+        updateWatchOnlyLabels(wallet.haveWatchOnly() && !wallet.privateKeysDisabled());
         connect(model, &WalletModel::notifyWatchonlyChanged, [this](bool showWatchOnly) {
             updateWatchOnlyLabels(showWatchOnly && !walletModel->wallet().privateKeysDisabled());
         });