Merge pull request #131 from CommunityToolkit/dev/remove-can-execute-checks

Remove CanExecute checks from Execute logic

Author: Sergio0694

CommunityToolkit.Mvvm/Input/AsyncRelayCommand.cs

@@ -280,36 +280,31 @@ public void Execute(object? parameter)
     /// <inheritdoc/>
     public Task ExecuteAsync(object? parameter)
     {
-        if (CanExecute(parameter))
-        {
-            Task executionTask;
+        Task executionTask;
 
-            if (this.execute is not null)
-            {
-                // Non cancelable command delegate
-                executionTask = ExecutionTask = this.execute();
-            }
-            else
-            {
-                // Cancel the previous operation, if one is pending
-                this.cancellationTokenSource?.Cancel();
-
-                CancellationTokenSource cancellationTokenSource = this.cancellationTokenSource = new();
+        if (this.execute is not null)
+        {
+            // Non cancelable command delegate
+            executionTask = ExecutionTask = this.execute();
+        }
+        else
+        {
+            // Cancel the previous operation, if one is pending
+            this.cancellationTokenSource?.Cancel();
 
-                // Invoke the cancelable command delegate with a new linked token
-                executionTask = ExecutionTask = this.cancelableExecute!(cancellationTokenSource.Token);
-            }
+            CancellationTokenSource cancellationTokenSource = this.cancellationTokenSource = new();
 
-            // If concurrent executions are disabled, notify the can execute change as well
-            if (!this.allowConcurrentExecutions)
-            {
-                CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-            }
+            // Invoke the cancelable command delegate with a new linked token
+            executionTask = ExecutionTask = this.cancelableExecute!(cancellationTokenSource.Token);
+        }
 
-            return executionTask;
+        // If concurrent executions are disabled, notify the can execute change as well
+        if (!this.allowConcurrentExecutions)
+        {
+            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
         }
 
-        return Task.CompletedTask;
+        return executionTask;
     }
 
     /// <inheritdoc/>

CommunityToolkit.Mvvm/Input/AsyncRelayCommand{T}.cs

@@ -282,37 +282,31 @@ public void Execute(object? parameter)
     /// <inheritdoc/>
     public Task ExecuteAsync(T? parameter)
     {
-        if (CanExecute(parameter))
-        {
-            Task executionTask;
+        Task executionTask;
 
-            
-            if (this.execute is not null)
-            {
-                // Non cancelable command delegate
-                executionTask = ExecutionTask = this.execute(parameter);
-            }
-            else
-            {
-                // Cancel the previous operation, if one is pending
-                this.cancellationTokenSource?.Cancel();
-
-                CancellationTokenSource cancellationTokenSource = this.cancellationTokenSource = new();
+        if (this.execute is not null)
+        {
+            // Non cancelable command delegate
+            executionTask = ExecutionTask = this.execute(parameter);
+        }
+        else
+        {
+            // Cancel the previous operation, if one is pending
+            this.cancellationTokenSource?.Cancel();
 
-                // Invoke the cancelable command delegate with a new linked token
-                executionTask = ExecutionTask = this.cancelableExecute!(parameter, cancellationTokenSource.Token);
-            }
+            CancellationTokenSource cancellationTokenSource = this.cancellationTokenSource = new();
 
-            // If concurrent executions are disabled, notify the can execute change as well
-            if (!this.allowConcurrentExecutions)
-            {
-                CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-            }
+            // Invoke the cancelable command delegate with a new linked token
+            executionTask = ExecutionTask = this.cancelableExecute!(parameter, cancellationTokenSource.Token);
+        }
 
-            return executionTask;
+        // If concurrent executions are disabled, notify the can execute change as well
+        if (!this.allowConcurrentExecutions)
+        {
+            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
         }
 
-        return Task.CompletedTask;
+        return executionTask;
     }
 
     /// <inheritdoc/>

CommunityToolkit.Mvvm/Input/RelayCommand.cs

@@ -74,9 +74,6 @@ public bool CanExecute(object? parameter)
     /// <inheritdoc/>
     public void Execute(object? parameter)
     {
-        if (CanExecute(parameter))
-        {
-            this.execute();
-        }
+        this.execute();
     }
 }

CommunityToolkit.Mvvm/Input/RelayCommand{T}.cs

@@ -94,10 +94,7 @@ public bool CanExecute(object? parameter)
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void Execute(T? parameter)
     {
-        if (CanExecute(parameter))
-        {
-            this.execute(parameter);
-        }
+        this.execute(parameter);
     }
 
     /// <inheritdoc/>

tests/CommunityToolkit.Mvvm.UnitTests/Test_AsyncRelayCommand.cs

@@ -112,11 +112,13 @@ public void Test_AsyncRelayCommand_WithCanExecuteFunctionFalse()
 
         command.Execute(null);
 
-        Assert.AreEqual(ticks, 0);
+        // It is the caller's responsibility to ensure that CanExecute is true
+        // before calling Execute. This check verifies the logic is still called.
+        Assert.AreEqual(ticks, 1);
 
         command.Execute(new object());
 
-        Assert.AreEqual(ticks, 0);
+        Assert.AreEqual(ticks, 2);
     }
 
     [TestMethod]
@@ -289,11 +291,6 @@ private static async Task Test_AsyncRelayCommand_AllowConcurrentExecutions_TestL
         Assert.IsFalse(command.CanBeCanceled);
         Assert.IsFalse(command.IsCancellationRequested);
 
-        Task newTask = command.ExecuteAsync(null);
-
-        // Execution failed, so a completed task was returned
-        Assert.AreSame(newTask, Task.CompletedTask);
-
         tcs.SetResult(null);
 
         await task;

tests/CommunityToolkit.Mvvm.UnitTests/Test_AsyncRelayCommand{T}.cs

@@ -105,11 +105,12 @@ public void Test_AsyncRelayCommandOfT_WithCanExecuteFunctionFalse()
 
         command.Execute("2");
 
-        Assert.AreEqual(ticks, 0);
+        // Like in the RelayCommand test, ensure Execute is unconditionally invoked
+        Assert.AreEqual(ticks, 2);
 
         command.Execute("42");
 
-        Assert.AreEqual(ticks, 0);
+        Assert.AreEqual(ticks, 42);
     }
 
     [TestMethod]
@@ -231,11 +232,6 @@ private static async Task Test_AsyncRelayCommandOfT_AllowConcurrentExecutions_Te
         Assert.IsFalse(command.CanBeCanceled);
         Assert.IsFalse(command.IsCancellationRequested);
 
-        Task newTask = command.ExecuteAsync(null);
-
-        // Execution failed, so a completed task was returned
-        Assert.AreSame(newTask, Task.CompletedTask);
-
         tcs.SetResult(null);
 
         await task;