nunit UITest xamarin.forms: how to scroll a picker? - unit-testing

Question

I am trying to create UITest for Xamarin.Forms project. Do testing on Android.
I have tryed using some inf available on Xamarin forum but had no luck with it.
Country list for the Picker:
List<country> countryList = new List<country>({id="GB", name="United Kingdom"}, {id="US", name="United States"}.... etc);
Code for Picker:
var countryPicker = new Picker();
countryPicker.SetBinding(Picker.SelectedIndexProperty, "myIndex");
countryPicker.BindingContext = getCountry;
countryPicker.BackgroundColor = Color.White;
countryPicker.AutomationId = "countryPicker";
countryPicker.SelectedIndexChanged += ((s, e) =>
{
foreach (var element in countryList)
{
if (element.name.Equals(countryPicker.Items[countryPicker.SelectedIndex]))
{
getCountry.myCountry = element.id;
}
}
});
//adding all the countries to the list
foreach (var item in countryList)
{
countryPicker.Items.Add(item.name);
}
nunit code:
app.Query(c=>c.Marked("countryPicker").Invoke("selectValue", "United States"));
Answer: Query for Marked("countryPicker").Invoke("selectValue", "United States") gave 1 results.
But nothing is happening - selection is not done!
I've tryed to select value to "US" - same, no result.
Am I missing something?

Answer 1

Open Xamarin.Form Picker, Select, & Test result (Android only):
// Open up the picker
app.Tap(x => x.Marked("countryPicker"));
// Try to scroll and find the text item only 5 times
for (int i = 0; i< 5; i++)
{
if (app.Query(m => m.Text("United States")).Length == 0)
app.ScrollDown(x => x.Id("select_dialog_listview"));
else
{
app.Tap(x => x.Text("United States"));
break;
}
}
Assert.IsTrue(app.Query("countryPicker")[0].Text == "United States");
Open Xamarin.Form Picker, Select, & Test result (iOS only):
/// Open up the picker
app.Tap(x => x.Marked("countryPicker"));
// Assuming a single column picker
var picker = app.Query(x => x.Class(pickerClass).Index(0));
// Try to scroll and find the text item only 5 times
for (int i = 0; i < 5; i++)
{
if (app.Query(m => m.Text("United States")).Length == 0)
app.ScrollDown(x => x.Class("UIPickerTableView").Index(0));
else
{
app.Tap(x => x.Text("United States"));
break;
}
}
app.Tap(x => x.Class("UIToolbarTextButton"));
Assert.IsTrue(app.Query("countryPicker")[0].Text == "United States");

Answer 2

The following solutions are also now available and won't break when your picker has a value outside of the 5 scroll limit set above. I'm using a NumberPicker in this example but the same approaches should work with a CountryPicker:
if (platform == Platform.iOS) {
app.Query(x => x.Class("UIPickerView").Invoke("selectRow", 3, "inComponent", 0, "animated", true));
// This is a hack to move the item so that Xamarin Forms will generate the event to update the UI
var rect = app.Query(x => x.Class("UIPickerTableView").Index(0).Child()).First().Rect;
app.DragCoordinates(rect.CenterX, rect.CenterY, rect.CenterX, rect.CenterY + 20);
app.Tap(c => c.Text("Done"));
}
else {
//NOTE: On Android the values appear to be out by one - setting 4 selects the 3rd value.
var results = app.Query(c => c.Class("numberPicker").Invoke("setValue", 4));
var text = app.Query("PickerControl")[0].Text;
app.Tap(c => c.Text(text));
//You can also do it like this on Android:
// app.ScrollDownTo(m => m.Text("White"), x => x.Id("select_dialog_listview"));
// app.Tap(x => x.Text("White"));
// Assert.IsTrue(app.Query("PickerControl")[0].Text == "White");
}
You can use these solutions after opening the picker.
Of particular note is the small "nudge" on iOS - if you select the picker value using selectRow the UI doesn't flag as updated. This hack causes the necessary events to fire and the UI gets updated.