In RazorCompiler, support expressions with non-string or null values

src/Microsoft.Blazor/RenderTree/RenderTreeBuilder.cs

@@ -59,6 +59,13 @@ namespace Microsoft.Blazor.RenderTree
         public void AddText(string textContent)
             => Append(RenderTreeNode.Text(textContent));
 
+        /// <summary>
+        /// Appends a node representing text content.
+        /// </summary>
+        /// <param name="textContent">Content for the new text node.</param>
+        public void AddText(object textContent)
+            => AddText(textContent?.ToString());
+
         /// <summary>
         /// Appends a node representing a string-valued attribute.
         /// The attribute is associated with the most recently added element.

src/Microsoft.Blazor/RenderTree/RenderTreeNode.cs

@@ -77,7 +77,7 @@ namespace Microsoft.Blazor.RenderTree
         internal static RenderTreeNode Text(string textContent) => new RenderTreeNode
         {
             NodeType = RenderTreeNodeType.Text,
-            TextContent = textContent,
+            TextContent = textContent ?? string.Empty,
         };
 
         internal static RenderTreeNode Attribute(string name, string value) => new RenderTreeNode

test/Microsoft.Blazor.Build.Test/RazorCompilerTest.cs

@@ -100,6 +100,25 @@ namespace Microsoft.Blazor.Build.Test
                 node => AssertNode.Text(node, "Some plain text"));
         }
 
+        [Fact]
+        public void SupportsCSharpExpressions()
+        {
+            // Arrange/Act
+            var component = CompileToComponent(@"
+                @(""Hello"")
+                @((object)null)
+                @(123)
+                @(new object())
+            ");
+
+            // Assert
+            var nodes = GetRenderTree(component).Where(NotWhitespace);
+            Assert.Collection(nodes,
+                node => AssertNode.Text(node, "Hello"),
+                node => AssertNode.Text(node, "123"),
+                node => AssertNode.Text(node, new object().ToString()));
+        }
+
         [Fact]
         public void SupportsCSharpFunctionsBlock()
         {

test/Microsoft.Blazor.Test/RenderTreeBuilderTest.cs

@@ -40,9 +40,11 @@ namespace Microsoft.Blazor.Test
         {
             // Arrange
             var builder = new RenderTreeBuilder(new TestRenderer());
+            var nullString = (string)null;
 
             // Act
             builder.AddText("First item");
+            builder.AddText(nullString);
             builder.AddText("Second item");
 
             // Assert
@@ -50,9 +52,29 @@ namespace Microsoft.Blazor.Test
             Assert.Equal(0, nodes.Offset);
             Assert.Collection(nodes,
                 node => AssertNode.Text(node, "First item"),
+                node => AssertNode.Text(node, string.Empty),
                 node => AssertNode.Text(node, "Second item"));
         }
 
+        [Fact]
+        public void CanAddNonStringValueAsText()
+        {
+            // Arrange
+            var builder = new RenderTreeBuilder(new TestRenderer());
+            var nullObject = (object)null;
+
+            // Act
+            builder.AddText(1234);
+            builder.AddText(nullObject);
+
+            // Assert
+            var nodes = builder.GetNodes();
+            Assert.Equal(0, nodes.Offset);
+            Assert.Collection(nodes,
+                node => AssertNode.Text(node, "1234"),
+                node => AssertNode.Text(node, string.Empty));
+        }
+
         [Fact]
         public void UnclosedElementsHaveNoEndDescendantIndex()
         {

test/testapps/BasicTestApp/CounterComponent.cshtml

@@ -1,5 +1,5 @@
 <h1>Counter</h1>
-<p>Current count: @currentCount.ToString()</p>
+<p>Current count: @currentCount</p>
 <button onclick=@OnButtonClicked>Click me</button>
 
 @functions {