Time Picker behaves erractically when min and max is set

[Nicholas Skaggs]

Using this example qml,

import QtQuick 2.0
import Ubuntu.Components 1.1
import Ubuntu.Components.Pickers 1.0

MainView {
    width: units.gu(48)
    height: units.gu(60)

    Column {
        DatePicker {
            id: datePicker
            objectName: 'datePicker'
            mode: 'Years|Months|Days'
            maximum: {
                var d = new Date()
                d.setFullYear('2030')
                return d
            }
            minimum: {
                var d = new Date()
                d.setFullYear('1990')
                return d
            }
            date: {
                var d = new Date()
                d.setFullYear('2010')
                d.setMonth('5')
                d.setDate('15')
                return d
            }
        }
        DatePicker {
            id: timePicker
            objectName: 'timePicker'
            mode: 'Hours|Minutes|Seconds'
            maximum: {
                var d = new Date()
                d.setFullYear('2030')
                return d
            }
            minimum: {
                var d = new Date()
                d.setFullYear('1990')
                return d
            }
            date: {
                var d = new Date()
                d.setHours(12)
                d.setMinutes('30')
                d.setSeconds('30')
                return d
            }
        }
    }
}

The timepicker behaves erractically. When selecting a minute, the hour picker. When selecting things with the second picker, both the hour and minute pickers advance forward as well.

It's interesting the min and max dates are being set (this was discovered trying to workaround bug https://bugs.launchpad.net/ubuntu-calendar-app/+bug/1328600) as a timepicker likely doesn't make sense to have a year, but since they can be set the pickers likely should behave properly when done so.

[Nicholas Skaggs (nskaggs)]

Let's please expand the pickers testcases to include a regression test for this so we don't regress on it in the future. It would be trivial to add.

[Zsombor Egri (zsombi)]

Ok, I guess I got the point. The logic adjusting the time is erroneous depending on the change. If the time component is set forward to the previous value (i.e. seconds), the major time component is also adjusted (i.e. minutes). This is due to a binding loop inside the DatePicker:
"modules/Ubuntu/Components/Pickers/DatePicker.qml:400, unknown) - file:///home/zsombor/projects/datepicker-fix-1346669/modules/Ubuntu/Components/Pickers/DatePicker.qml:400:5: QML MinutesModel: Binding loop detected for property "date""

And I cannot find a pattern to reproduce. So me times the failure happens immediately I run the app, sometimes it only happens on hour, sometimes happens only if at least two tumblers are spanned same time. And sometimes the binding loop does not appear but the failure is there... This is hard to create a test to.