Add support for "On" prefix for command methods

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/Input/ICommandGenerator.Execute.cs

@@ -350,6 +350,17 @@ public static (string FieldName, string PropertyName) GetGeneratedFieldAndProper
         {
             string propertyName = methodSymbol.Name;
 
+            // Strip the "On" prefix, if present. Only do this if the name is longer than 2 characters,
+            // and if the 3rd character is not a lowercase letter. This is needed to avoid accidentally
+            // stripping fales positives for "On" prefixes in names such as "Onboard".
+            if (propertyName.Length > 2 &&
+                propertyName.StartsWith("On") &&
+                !char.IsLower(propertyName[2]))
+            {
+                propertyName = propertyName.Substring(2);
+            }
+
+            // Strip the "Async" suffix for methods returning a Task type
             if (methodSymbol.Name.EndsWith("Async") &&
                 (methodSymbol.ReturnType.HasFullyQualifiedName("global::System.Threading.Tasks.Task") ||
                  methodSymbol.ReturnType.InheritsFromFullyQualifiedName("global::System.Threading.Tasks.Task")))

tests/CommunityToolkit.Mvvm.UnitTests/Test_ICommandAttribute.cs

@@ -472,6 +472,34 @@ public void Test_ICommandAttribute_CultureAwareCommandName()
         model.InitializeCommand.Execute(null);
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/162
+    [TestMethod]
+    public async Task Test_ICommandAttribute_WithOnPrefixes()
+    {
+        ModelWithCommandMethodsWithOnPrefixes model = new();
+
+        Assert.IsFalse(model.HasOnCommandRun);
+        Assert.IsFalse(model.HasOnboardCommandRun);
+        Assert.IsFalse(model.HasSubmitCommandRun);
+        Assert.IsFalse(model.HasDownloadCommandRun);
+
+        model.OnCommand.Execute(null);
+
+        Assert.IsTrue(model.HasOnCommandRun);
+
+        model.OnboardCommand.Execute(null);
+
+        Assert.IsTrue(model.HasOnboardCommandRun);
+
+        model.SubmitCommand.Execute(null);
+
+        Assert.IsTrue(model.HasSubmitCommandRun);
+
+        await model.DownloadCommand.ExecuteAsync(null);
+
+        Assert.IsTrue(model.HasDownloadCommandRun);
+    }
+
     #region Region
     public class Region
     {
@@ -806,4 +834,41 @@ private void Initialize()
         {
         }
     }
+
+    partial class ModelWithCommandMethodsWithOnPrefixes
+    {
+        public bool HasOnCommandRun { get; private set; }
+
+        public bool HasOnboardCommandRun { get; private set; }
+
+        public bool HasSubmitCommandRun { get; private set; }
+
+        public bool HasDownloadCommandRun { get; private set; }
+
+        [ICommand]
+        private void On()
+        {
+            HasOnCommandRun = true;
+        }
+
+        [ICommand]
+        private void Onboard()
+        {
+            HasOnboardCommandRun = true;
+        }
+
+        [ICommand]
+        private void OnSubmit()
+        {
+            HasSubmitCommandRun = true;
+        }
+
+        [ICommand]
+        private async Task OnDownloadAsync()
+        {
+            await Task.Delay(100);
+
+            HasDownloadCommandRun = true;
+        }
+    }
 }