Replace code snippet with link to analyzer template and instructions

src/Microsoft.CodeAnalysis.Testing/README.md

@@ -198,76 +198,7 @@ verifier and test types. For example, [Microsoft/vs-threading](https://github.co
 Additional Files and metadata references in most of its tests, so it uses custom verifier and test types to allow the
 use of "basic use cases" for test scenarios that would otherwise be considered advanced.
 
-```csharp
-public static class CSharpAnalyzerVerifier<TAnalyzer>
-    where TAnalyzer : DiagnosticAnalyzer, new()
-{
-    public static DiagnosticResult Diagnostic()
-        => CSharpAnalyzerVerifier<TAnalyzer, DefaultVerifier>.Diagnostic();
-
-    public static DiagnosticResult Diagnostic(string diagnosticId)
-        => CSharpAnalyzerVerifier<TAnalyzer, DefaultVerifier>.Diagnostic(diagnosticId);
-
-    public static DiagnosticResult Diagnostic(DiagnosticDescriptor descriptor)
-        => new DiagnosticResult(descriptor);
-
-    public static Task VerifyAnalyzerAsync(string source, params DiagnosticResult[] expected)
-    {
-        var test = new Test { TestCode = source };
-        test.ExpectedDiagnostics.AddRange(expected);
-        return test.RunAsync();
-    }
-
-    // Code fix tests support both analyzer and code fix testing. This test class is derived from the code fix test
-    // to avoid the need to maintain duplicate copies of the customization work.
-    public class Test : CSharpCodeFixVerifier<TAnalyzer, EmptyCodeFixProvider>.Test
-    {
-    }
-}
-
-public static class CSharpCodeFixVerifier<TAnalyzer, TCodeFix>
-    where TAnalyzer : DiagnosticAnalyzer, new()
-    where TCodeFix : CodeFixProvider, new()
-{
-    public static DiagnosticResult Diagnostic(string diagnosticId)
-        => CSharpCodeFixVerifier<TAnalyzer, TCodeFix, DefaultVerifier>.Diagnostic(diagnosticId);
-
-    public static DiagnosticResult Diagnostic(DiagnosticDescriptor descriptor)
-        => new DiagnosticResult(descriptor);
-
-    public static Task VerifyAnalyzerAsync(string source, params DiagnosticResult[] expected)
-    {
-        var test = new CSharpAnalyzerVerifier<TAnalyzer>.Test { TestCode = source };
-        test.ExpectedDiagnostics.AddRange(expected);
-        return test.RunAsync();
-    }
-
-    public static Task VerifyCodeFixAsync(string source, string fixedSource)
-        => VerifyCodeFixAsync(source, DiagnosticResult.EmptyDiagnosticResults, fixedSource);
-
-    public static Task VerifyCodeFixAsync(string source, DiagnosticResult expected, string fixedSource)
-        => VerifyCodeFixAsync(source, new[] { expected }, fixedSource);
-
-    public static Task VerifyCodeFixAsync(string source, DiagnosticResult[] expected, string fixedSource)
-    {
-        var test = new Test
-        {
-            TestCode = source,
-            FixedCode = fixedSource,
-        };
-
-        test.ExpectedDiagnostics.AddRange(expected);
-        return test.RunAsync();
-    }
-
-    public class Test : CSharpCodeFixTest<TAnalyzer, TCodeFix, DefaultVerifier>
-    {
-        public Test()
-        {
-            // Custom initialization logic here
-        }
-
-        // Custom analyzers and/or code fix properties here
-    }
-}
-```
+To create a custom verifier, add your test setup or configuration to the corresponding `Test` class provided by the
+[analyzer template](../VisualStudio.Roslyn.SDK/Roslyn.SDK/ProjectTemplates/CSharp/Diagnostic/Test/Verifiers). See
+https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/tutorials/how-to-write-csharp-analyzer-code-fix for
+instructions on using the analyzer template.