Added failing tests for #3545.

`PropertyChanged` is not being fired when binding is disposed. Also change some other unit tests to ensure that priority passed in event args is correct.

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Binding.cs

@@ -132,6 +132,111 @@ namespace Avalonia.Base.UnitTests
             Assert.Equal("foo", target.GetValue(property));
         }
 
+        [Fact]
+        public void Completing_LocalValue_Binding_Raises_PropertyChanged()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<BindingValue<string>>("foo");
+            var property = Class1.FooProperty;
+            var raised = 0;
+
+            target.Bind(property, source);
+            Assert.Equal("foo", target.GetValue(property));
+
+            target.PropertyChanged += (s, e) =>
+            {
+                Assert.Equal(BindingPriority.Unset, e.Priority);
+                Assert.Equal(property, e.Property);
+                Assert.Equal("foo", e.OldValue as string);
+                Assert.Equal("foodefault", e.NewValue as string);
+                ++raised;
+            };
+
+            source.OnCompleted();
+
+            Assert.Equal("foodefault", target.GetValue(property));
+            Assert.Equal(1, raised);
+        }
+
+        [Fact]
+        public void Completing_Style_Binding_Raises_PropertyChanged()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<BindingValue<string>>("foo");
+            var property = Class1.FooProperty;
+            var raised = 0;
+
+            target.Bind(property, source, BindingPriority.Style);
+            Assert.Equal("foo", target.GetValue(property));
+
+            target.PropertyChanged += (s, e) =>
+            {
+                Assert.Equal(BindingPriority.Unset, e.Priority);
+                Assert.Equal(property, e.Property);
+                Assert.Equal("foo", e.OldValue as string);
+                Assert.Equal("foodefault", e.NewValue as string);
+                ++raised;
+            };
+
+            source.OnCompleted();
+
+            Assert.Equal("foodefault", target.GetValue(property));
+            Assert.Equal(1, raised);
+        }
+
+        [Fact]
+        public void Completing_LocalValue_Binding_With_Style_Binding_Raises_PropertyChanged()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<BindingValue<string>>("foo");
+            var property = Class1.FooProperty;
+            var raised = 0;
+
+            target.Bind(property, new BehaviorSubject<string>("bar"), BindingPriority.Style);
+            target.Bind(property, source);
+            Assert.Equal("foo", target.GetValue(property));
+
+            target.PropertyChanged += (s, e) =>
+            {
+                Assert.Equal(BindingPriority.Style, e.Priority);
+                Assert.Equal(property, e.Property);
+                Assert.Equal("foo", e.OldValue as string);
+                Assert.Equal("bar", e.NewValue as string);
+                ++raised;
+            };
+
+            source.OnCompleted();
+
+            Assert.Equal("bar", target.GetValue(property));
+            Assert.Equal(1, raised);
+        }
+
+        [Fact]
+        public void Disposing_LocalValue_Binding_Raises_PropertyChanged()
+        {
+            var target = new Class1();
+            var source = new BehaviorSubject<BindingValue<string>>("foo");
+            var property = Class1.FooProperty;
+            var raised = 0;
+
+            var sub = target.Bind(property, source);
+            Assert.Equal("foo", target.GetValue(property));
+
+            target.PropertyChanged += (s, e) =>
+            {
+                Assert.Equal(BindingPriority.Unset, e.Priority);
+                Assert.Equal(property, e.Property);
+                Assert.Equal("foo", e.OldValue as string);
+                Assert.Equal("foodefault", e.NewValue as string);
+                ++raised;
+            };
+
+            sub.Dispose();
+
+            Assert.Equal("foodefault", target.GetValue(property));
+            Assert.Equal(1, raised);
+        }
+
         [Fact]
         public void Setting_Style_Value_Overrides_Binding_Permanently()
         {

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs

@@ -188,6 +188,7 @@ namespace Avalonia.Base.UnitTests
             target.PropertyChanged += (s, e) =>
             {
                 Assert.Same(target, s);
+                Assert.Equal(BindingPriority.LocalValue, e.Priority);
                 Assert.Equal(Class1.FooProperty, e.Property);
                 Assert.Equal("newvalue", (string)e.OldValue);
                 Assert.Equal("unset", (string)e.NewValue);

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_SetValue.cs

@@ -30,6 +30,7 @@ namespace Avalonia.Base.UnitTests
             target.PropertyChanged += (s, e) =>
             {
                 Assert.Same(target, s);
+                Assert.Equal(BindingPriority.Unset, e.Priority);
                 Assert.Equal(Class1.FooProperty, e.Property);
                 Assert.Equal("newvalue", (string)e.OldValue);
                 Assert.Equal("foodefault", (string)e.NewValue);