fix(passwordbox): Don't fail on setting null on PasswordBox.Password

Author: jeromelaban

src/Uno.UI.Tests/Windows_UI_XAML_Controls/PasswordBoxTests/Given_PasswordBox.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Data;
+
+namespace Uno.UI.Tests.PasswordBoxTests
+{
+	[TestClass]
+	public class Given_PasswordBox
+	{
+		[TestMethod]
+		public void When_Binding_Set_Null()
+		{
+			var passwordBox = new PasswordBox();
+			var source = new MySource() { SourceText = "Spinach" };
+
+			passwordBox.DataContext = source;
+			passwordBox.SetBinding(PasswordBox.PasswordProperty, new Binding() { Path = new PropertyPath("SourceText") });
+
+			Assert.AreEqual("Spinach", passwordBox.Password);
+
+			source.SourceText = null;
+
+			Assert.AreEqual("", passwordBox.Password);
+		}
+
+		[TestMethod]
+		public void When_Set_DP_Null()
+		{
+			var passwordBox = new PasswordBox();
+
+			passwordBox.SetValue(PasswordBox.PasswordProperty, "Spinach");
+			Assert.AreEqual("Spinach", passwordBox.Password);
+			passwordBox.SetValue(PasswordBox.PasswordProperty, null);
+			Assert.AreEqual("", passwordBox.Password);
+		}
+
+		[TestMethod]
+		public void When_Binding_Set_Non_String()
+		{
+			var passwordBox = new PasswordBox();
+			var source = new MySource() { SourceInt = 12 };
+
+			passwordBox.DataContext = source;
+			passwordBox.SetBinding(PasswordBox.PasswordProperty, new Binding() { Path = new PropertyPath("SourceInt") });
+
+			Assert.AreEqual("12", passwordBox.Password);
+
+			source.SourceInt = 19;
+
+			Assert.AreEqual("19", passwordBox.Password);
+		}
+
+		public class MySource : System.ComponentModel.INotifyPropertyChanged
+		{
+			private string _sourceText;
+
+			public string SourceText
+			{
+				get => _sourceText;
+				set
+				{
+					if (_sourceText != value)
+					{
+						_sourceText = value;
+						OnPropertyChanged(); 
+					}
+				}
+			}
+
+			private int _sourceInt;
+
+			public int SourceInt
+			{
+				get => _sourceInt;
+				set
+				{
+					if (_sourceInt != value)
+					{
+						_sourceInt = value;
+						OnPropertyChanged();
+					}
+				}
+			}
+
+			public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
+
+			protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+				=> PropertyChanged?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
+		}
+	}
+}

src/Uno.UI/UI/Xaml/Controls/PasswordBox/PasswordBox.cs

@@ -103,7 +103,7 @@ public string Password
 
 		private void OnPasswordChanged(DependencyPropertyChangedEventArgs e)
 		{
-			Text = (string)e.NewValue;
+			SetValue(TextProperty, (string)e.NewValue);
 
 			PasswordChanged?.Invoke(this, new RoutedEventArgs(this));
 
@@ -124,7 +124,7 @@ protected override void OnTextChanged(DependencyPropertyChangedEventArgs e)
 		{
 			base.OnTextChanged(e);
 
-			Password = (string)e.NewValue;
+			SetValue(PasswordProperty, (string)e.NewValue);
 		}
 
 		protected override AutomationPeer OnCreateAutomationPeer()