Support "Fix One" analyzer test scenarios

eng/Versions.props

@@ -28,7 +28,7 @@
     <!-- Versions used by several individual references below -->
     <RoslynDiagnosticsNugetPackageVersion>3.0.0-beta2.20059.3+77df2220</RoslynDiagnosticsNugetPackageVersion>
     <CodeStyleLayerCodeAnalysisVersion>3.3.1</CodeStyleLayerCodeAnalysisVersion>
-    <MicrosoftCodeAnalysisTestingVersion>1.0.1-beta1.20118.1</MicrosoftCodeAnalysisTestingVersion>
+    <MicrosoftCodeAnalysisTestingVersion>1.0.1-beta1.20126.2</MicrosoftCodeAnalysisTestingVersion>
     <CodeStyleAnalyzerVersion>3.5.0-beta3-20078-04</CodeStyleAnalyzerVersion>
     <VisualStudioEditorPackagesVersion>16.4.248</VisualStudioEditorPackagesVersion>
     <ILToolsPackageVersion>5.0.0-alpha1.19409.1</ILToolsPackageVersion>

src/EditorFeatures/TestUtilities/CodeActions/CSharpCodeFixVerifier`2+Test.cs

@@ -82,10 +82,18 @@ public Test()
             /// </summary>
             public OptionsCollection Options { get; } = new OptionsCollection(LanguageNames.CSharp);
 
+            public Func<ImmutableArray<Diagnostic>, Diagnostic?>? DiagnosticSelector { get; set; }
+
             protected override AnalyzerOptions GetAnalyzerOptions(Project project)
             {
                 return new WorkspaceAnalyzerOptions(base.GetAnalyzerOptions(project), project.Solution);
             }
+
+            protected override Diagnostic? TrySelectDiagnosticToFix(ImmutableArray<Diagnostic> fixableDiagnostics)
+            {
+                return DiagnosticSelector?.Invoke(fixableDiagnostics)
+                    ?? base.TrySelectDiagnosticToFix(fixableDiagnostics);
+            }
         }
     }
 }

src/EditorFeatures/TestUtilities/CodeActions/VisualBasicCodeFixVerifier`2+Test.cs

@@ -4,6 +4,8 @@
 
 #nullable enable
 
+using System;
+using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Shared.Extensions;
@@ -53,10 +55,18 @@ public Test()
             /// </summary>
             public OptionsCollection Options { get; } = new OptionsCollection(LanguageNames.VisualBasic);
 
+            public Func<ImmutableArray<Diagnostic>, Diagnostic?>? DiagnosticSelector { get; set; }
+
             protected override AnalyzerOptions GetAnalyzerOptions(Project project)
             {
                 return new WorkspaceAnalyzerOptions(base.GetAnalyzerOptions(project), project.Solution);
             }
+
+            protected override Diagnostic? TrySelectDiagnosticToFix(ImmutableArray<Diagnostic> fixableDiagnostics)
+            {
+                return DiagnosticSelector?.Invoke(fixableDiagnostics)
+                    ?? base.TrySelectDiagnosticToFix(fixableDiagnostics);
+            }
         }
     }
 }