Wrapper xml parsing in try/catch to provide better error message to unit test runner

Author: egil

src/Egil.RazorComponents.Testing.Library.csproj

@@ -14,7 +14,7 @@
     <RepositoryUrl>https://github.com/egil/razor-components-testing-library</RepositoryUrl>
     <PackageProjectUrl>https://github.com/egil/razor-components-testing-library</PackageProjectUrl>
     <PackageTags>razor-components unit-testing testing blazor blazor-server-side blazor-client-side</PackageTags>
-    <Version>0.1.0-preview7-19365-7-2</Version>
+    <Version>0.1.0-preview7-19365-7-3</Version>
     <Authors>Egil Hansen</Authors>
     <Company>Egil Hansen</Company>
     <Product>Razor Component Testing Library</Product>

src/RazerComponentTestRenderer.cs

@@ -13,6 +13,8 @@ namespace Egil.RazorComponents.Testing
 {
     public class RazerComponentTestRenderer : IDisposable
     {
+        private const string RenderResultsElement = "RenderResults";
+
         private readonly IDispatcher _dispatcher = Renderer.CreateDefaultDispatcher();
         private readonly Func<string, string> _encoder = (t) => HtmlEncoder.Default.Encode(t);
 
@@ -39,7 +41,7 @@ private IReadOnlyList<TestRenderResult> GetTestResults(HtmlRenderer htmlRenderer
         {
             var renderTask = _dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<RenderFragmentWrapper>(parameterCollection));
             var renderResult = GetResult(renderTask);
-            return ParseRawXml(string.Concat(renderResult.Tokens));
+            return ProcessRenderResult(string.Concat(renderResult.Tokens));
         }
 
         private static ComponentRenderedText GetResult(Task<ComponentRenderedText> task)
@@ -57,15 +59,12 @@ private static ComponentRenderedText GetResult(Task<ComponentRenderedText> task)
             }
         }
 
-        private static IReadOnlyList<TestRenderResult> ParseRawXml(string renderResults)
+        private static IReadOnlyList<TestRenderResult> ProcessRenderResult(string renderResults)
         {
-            const string renderResultsElement = "RenderResults";
-
-            var xml = new XmlDocument();
-            xml.LoadXml($"<{renderResultsElement}>{renderResults}</{renderResultsElement}>");
+            var xml = LoadRenderResult(renderResults);
 
             var result = new List<TestRenderResult>();
-            foreach (XmlNode? node in xml.SelectNodes($"{renderResultsElement}/{Fact.ElementName}"))
+            foreach (XmlNode? node in xml.SelectNodes($"{RenderResultsElement}/{Fact.ElementName}"))
             {
                 if (node is null) continue;
 
@@ -80,5 +79,21 @@ private static IReadOnlyList<TestRenderResult> ParseRawXml(string renderResults)
 
             return result.AsReadOnly();
         }
+
+        private static XmlDocument LoadRenderResult(string renderResults)
+        {
+            var renderResultXml = $"<{RenderResultsElement}>{renderResults}</{RenderResultsElement}>";
+            var xml = new XmlDocument();
+            try
+            {
+                xml.LoadXml(renderResultXml);
+                return xml;
+            }
+            catch (XmlException ex)
+            {
+                throw new RazorComponentRenderResultParseException($"An error occurred while trying to parse the " +
+                    $"render result of the test. Result XML: {Environment.NewLine}{renderResultXml}", ex);
+            }
+        }
     }
 }

src/RazorComponentRenderResultParseException.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Runtime.Serialization;
+using Xunit.Sdk;
+
+namespace Egil.RazorComponents.Testing
+{
+    public class RazorComponentRenderResultParseException : XunitException
+    {
+        public RazorComponentRenderResultParseException(string userMessage, Exception innerException) : base(userMessage, innerException)
+        {
+        }
+    }
+}