Fix double refresh issue with RefreshView

[adrianknight89]

Description of Change

If you refresh a RefreshView and add a time delay beforehand (through Task.Delay or network latency), then previously we ended up calling the refresh command twice. This PR fixes the issue. Also added a UI test.

Issues Resolved

• related to [Bug] RefreshView pull to refresh command firing twice on a single pull #7803

Testing Procedure

Pull to refresh and make sure that the count shows 20 instead of 30.

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[jsuarezruiz]

LGTM.

[PureWeen]

Looking good!

What are your thoughts on moving the CanExecute up to the top and setting the value with it?

if(value && RefreshView?.Command != null)
	value = RefreshView.Command.CanExecute(RefreshView?.CommandParameter);

// Allow RefreshView.IsRefreshing to sync up with Refreshing
if (RefreshView != null && RefreshView.IsRefreshing != value)
{
	RefreshView.SetValueFromRenderer(RefreshView.IsRefreshingProperty, value);
	return;
}

_refreshing = value;

base.Refreshing = _refreshing;

if (base.Refreshing && RefreshView != null && RefreshView.Command != null)
	RefreshView.Command.Execute(RefreshView?.CommandParameter);

On a side note there is also a bug with RefreshView where the Command bound to it isn't correctly propagating to IsEnabled when the control is created (I'm creating a PR for this now)

So in theory IsRefresh should never be set to true if in fact the Commands can execute is false but it still feels odd to let the Refresh trigger if CanExecute is false.

[PureWeen]

Suggested change

	refreshView.IsRefreshing = value;
	refreshView.SetValueFromRenderer(RefreshView.IsRefreshingProperty, value);

[PureWeen]

Suggested change

	RefreshView.IsRefreshing = value;
	RefreshView.SetValueFromRenderer(RefreshView.IsRefreshingProperty, value);

[adrianknight89]

@PureWeen Can you review again? I made some changes to the property setter since it was bloated with several lines of code.

So in theory IsRefresh should never be set to true if in fact the Commands can execute is false but it still feels odd to let the Refresh trigger if CanExecute is false.

I'd agree with you, but the user can manually set IsRefreshing to true when the command is not executable. So why not allow this to be the same? I don't see any validation on IsRefreshingProperty based on the command:

public static readonly BindableProperty IsRefreshingProperty =
BindableProperty.Create(nameof(IsRefreshing), typeof(bool), typeof(RefreshView), false, BindingMode.TwoWay);