Enable invoking a `ViewComponent` without arguments inside of a controller.

- Also updated doc comments to properly reflect `ViewComponent` `arguments` parameter.

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Controller.cs

@@ -209,6 +209,32 @@ namespace Microsoft.AspNetCore.Mvc
             };
         }
 
+        /// <summary>
+        /// Creates a <see cref="ViewComponentResult"/> by specifying the name of a view component to render.
+        /// </summary>
+        /// <param name="componentName">
+        /// The view component name. Can be a view component
+        /// <see cref="ViewComponents.ViewComponentDescriptor.ShortName"/> or
+        /// <see cref="ViewComponents.ViewComponentDescriptor.FullName"/>.</param>
+        /// <returns>The created <see cref="ViewComponentResult"/> object for the response.</returns>
+        [NonAction]
+        public virtual ViewComponentResult ViewComponent(string componentName)
+        {
+            return ViewComponent(componentName, arguments: null);
+        }
+
+        /// <summary>
+        /// Creates a <see cref="ViewComponentResult"/> by specifying the <see cref="Type"/> of a view component to
+        /// render.
+        /// </summary>
+        /// <param name="componentType">The view component <see cref="Type"/>.</param>
+        /// <returns>The created <see cref="ViewComponentResult"/> object for the response.</returns>
+        [NonAction]
+        public virtual ViewComponentResult ViewComponent(Type componentType)
+        {
+            return ViewComponent(componentType, arguments: null);
+        }
+
         /// <summary>
         /// Creates a <see cref="ViewComponentResult"/> by specifying the name of a view component to render.
         /// </summary>
@@ -217,9 +243,9 @@ namespace Microsoft.AspNetCore.Mvc
         /// <see cref="ViewComponents.ViewComponentDescriptor.ShortName"/> or
         /// <see cref="ViewComponents.ViewComponentDescriptor.FullName"/>.</param>
         /// <param name="arguments">
-        /// An anonymous <see cref="object"/> containing arguments to be passed to the invoked view component method.
+        /// An <see cref="object"/> with properties representing arguments to be passed to the invoked view component
-        /// Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing
+        /// method. Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance
-        /// the invocation arguments.
+        /// containing the invocation arguments.
         /// </param>
         /// <returns>The created <see cref="ViewComponentResult"/> object for the response.</returns>
         [NonAction]
@@ -240,9 +266,9 @@ namespace Microsoft.AspNetCore.Mvc
         /// </summary>
         /// <param name="componentType">The view component <see cref="Type"/>.</param>
         /// <param name="arguments">
-        /// An anonymous <see cref="object"/> containing arguments to be passed to the invoked view component method.
+        /// An <see cref="object"/> with properties representing arguments to be passed to the invoked view component
-        /// Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing
+        /// method. Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance
-        /// the invocation arguments.
+        /// containing the invocation arguments.
         /// </param>
         /// <returns>The created <see cref="ViewComponentResult"/> object for the response.</returns>
         [NonAction]

src/Microsoft.AspNetCore.Mvc.ViewFeatures/IViewComponentHelper.cs

@@ -17,9 +17,9 @@ namespace Microsoft.AspNetCore.Mvc
         /// </summary>
         /// <param name="name">The name of the view component.</param>
         /// <param name="arguments">
-        /// An anonymous <see cref="object"/> containing arguments to be passed to the invoked view component method.
+        /// An <see cref="object"/> with properties representing arguments to be passed to the invoked view component
-        /// Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing
+        /// method. Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance
-        /// the invocation arguments.
+        /// containing the invocation arguments.
         /// </param>
         /// <returns>A <see cref="Task"/> that on completion returns the rendered <see cref="IHtmlContent" />.
         /// </returns>
@@ -30,9 +30,9 @@ namespace Microsoft.AspNetCore.Mvc
         /// </summary>
         /// <param name="componentType">The view component <see cref="Type"/>.</param>
         /// <param name="arguments">
-        /// An anonymous <see cref="object"/> containing arguments to be passed to the invoked view component method.
+        /// An <see cref="object"/> with properties representing arguments to be passed to the invoked view component
-        /// Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance containing
+        /// method. Alternatively, an <see cref="System.Collections.Generic.IDictionary{string, object}"/> instance
-        /// the invocation arguments.
+        /// containing the invocation arguments.
         /// </param>
         /// <returns>A <see cref="Task"/> that on completion returns the rendered <see cref="IHtmlContent" />.
         /// </returns>

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/ControllerUnitTestabilityTests.cs

@@ -560,7 +560,7 @@ namespace Microsoft.AspNetCore.Mvc
             var controller = new TestabilityController();
 
             // Act
-            var result = controller.ViewComponent("TagCloud", arguments: null);
+            var result = controller.ViewComponent("TagCloud");
 
             // Assert
             Assert.NotNull(result);
@@ -575,7 +575,7 @@ namespace Microsoft.AspNetCore.Mvc
             var controller = new TestabilityController();
 
             // Act
-            var result = controller.ViewComponent(typeof(TagCloudViewComponent), arguments: null);
+            var result = controller.ViewComponent(typeof(TagCloudViewComponent));
 
             // Assert
             Assert.NotNull(result);