Fix handling nonvoid elements in markup blocks (#1190)

* Fix empty nonvoid elements in markup blocks. Fixes #1186

* Also update another test

Author: SteveSandersonMS

src/Microsoft.AspNetCore.Blazor.Razor.Extensions/HtmlBlockPass.cs

@@ -200,7 +200,7 @@ public void VisitExtension(HtmlElementIntermediateNode node)
                 }
 
                 // If for some reason a void element contains body, then treat it as a
-                // start/end tag. Treat non-void elements without body content as self-closing.
+                // start/end tag.
                 if (!hasBodyContent && isVoid)
                 {
                     // void
@@ -209,8 +209,11 @@ public void VisitExtension(HtmlElementIntermediateNode node)
                 }
                 else if (!hasBodyContent)
                 {
-                    // self-closing
-                    Builder.Append("/>");
+                    // In HTML5, we can't have self-closing non-void elements, so explicitly
+                    // add a close tag
+                    Builder.Append("></");
+                    Builder.Append(node.TagName);
+                    Builder.Append(">");
                     return;
                 }
 

test/Microsoft.AspNetCore.Blazor.Build.Test/RenderingRazorIntegrationTest.cs

@@ -147,12 +147,12 @@ public void SupportsSelfClosingElementsWithDynamicContent()
         public void SupportsSelfClosingElementsAsStaticBlock()
         {
             // Arrange/Act
-            var component = CompileToComponent("Some text so elem isn't at position 0 <myelem />");
+            var component = CompileToComponent("Some text so elem isn't at position 0 <input attr='123' />");
 
             // Assert
             Assert.Collection(GetRenderTree(component),
                 frame => AssertFrame.Text(frame, "Some text so elem isn't at position 0 ", 0),
-                frame => AssertFrame.Markup(frame, "<myelem/>", 1));
+                frame => AssertFrame.Markup(frame, "<input attr=\"123\">", 1));
         }
 
         [Fact]

test/Microsoft.AspNetCore.Blazor.Razor.Extensions.Test/HtmlBlockPassTest.cs

@@ -109,12 +109,12 @@ public void Execute_RewritesHtml_CSharpInBody()
         }
 
         [Fact]
-        public void Execute_RewritesHtml_SelfClosing()
+        public void Execute_RewritesHtml_EmptyNonvoid()
         {
             // Arrange
             var document = CreateDocument(@"<a href=""...""></a>");
 
-            var expected = NormalizeContent(@"<a href=""...""/>");
+            var expected = NormalizeContent(@"<a href=""...""></a>");
 
             var documentNode = Lower(document);