Add overload for Set<T>() with custom IEqualityComparer (#113)

klemmchr · Jun 11, 2022 · 7115907 · 7115907
1 parent cd143b5
commit 7115907
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Showing 2 changed files with 46 additions and 3 deletions.
diff --git a/src/MvvmBlazor.Core/ViewModel/ViewModelBase.cs b/src/MvvmBlazor.Core/ViewModel/ViewModelBase.cs
@@ -1,4 +1,4 @@
-namespace MvvmBlazor.ViewModel;
+namespace MvvmBlazor.ViewModel;
 
 public abstract class ViewModelBase : INotifyPropertyChanged
 {
@@ -10,7 +10,13 @@ public abstract class ViewModelBase : INotifyPropertyChanged
 
     protected bool Set<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
     {
-        if (!EqualityComparer<T>.Default.Equals(field, value))
+        return Set(ref field, value, EqualityComparer<T>.Default, propertyName);
+    }
+
+    protected bool Set<T>(ref T field, T value, IEqualityComparer<T> equalityComparer, [CallerMemberName] string? propertyName = null)
+    {
+        ArgumentNullException.ThrowIfNull(equalityComparer);
+        if (!equalityComparer.Equals(field, value))
         {
             field = value;
             OnPropertyChanged(propertyName!);

diff --git a/src/MvvmBlazor.Tests/ViewModel/ViewModelBaseTests.cs b/src/MvvmBlazor.Tests/ViewModel/ViewModelBaseTests.cs
@@ -1,4 +1,4 @@
-namespace MvvmBlazor.Tests.ViewModel;
+namespace MvvmBlazor.Tests.ViewModel;
 
 public class ViewModelBaseTests
 {
@@ -76,11 +76,48 @@ void TestField<T>(ref T field, T value)
         TestField(ref double1, 2.3);
     }
 
+    [Fact]
+    public void Set_returns_False_with_custom_equality_comparer()
+    {
+        var mockEq= new StrictMock<IEqualityComparer<int>>();
+        mockEq.Setup(x => x.Equals(It.IsAny<int>(), It.IsAny<int>()))
+            .Returns(true)
+            .Verifiable();
+
+        var vm = new TestViewModel();
+        var int1 = 1;
+        var res = vm.SetProperty(ref int1, 2, mockEq.Object, "Foo");
+
+        res.ShouldBe(false);
+        mockEq.Verify();
+    }
+
+    [Fact]
+    public void Set_returns_true_with_custom_equality_comparer()
+    {
+        var mockEq= new StrictMock<IEqualityComparer<int>>();
+        mockEq.Setup(x => x.Equals(It.IsAny<int>(), It.IsAny<int>()))
+            .Returns(false)
+            .Verifiable();
+
+        var vm = new TestViewModel();
+        var int1 = 1;
+        var res = vm.SetProperty(ref int1, 1, mockEq.Object, "Foo");
+
+        res.ShouldBe(true);
+        mockEq.Verify();
+    }
+
     private class TestViewModel : ViewModelBase
     {
         public bool SetProperty<T>(ref T field, T value, string? propertyName = null)
         {
             return Set(ref field, value, propertyName);
         }
+
+        public bool SetProperty<T>(ref T field, T value, IEqualityComparer<T> equalityComparer, string? propertyName = null)
+        {
+            return Set(ref field, value, equalityComparer, propertyName);
+        }
     }
 }