Fix the ability to expand the list of analyzers in a reference

src/EditorFeatures/TestUtilities/Diagnostics/TestAnalyzerReferenceByLanguage.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
@@ -14,10 +12,13 @@ internal class TestAnalyzerReferenceByLanguage : AnalyzerReference
     {
         private readonly IReadOnlyDictionary<string, ImmutableArray<DiagnosticAnalyzer>> _analyzersMap;
 
-        public TestAnalyzerReferenceByLanguage(IReadOnlyDictionary<string, ImmutableArray<DiagnosticAnalyzer>> analyzersMap)
-            => _analyzersMap = analyzersMap;
+        public TestAnalyzerReferenceByLanguage(IReadOnlyDictionary<string, ImmutableArray<DiagnosticAnalyzer>> analyzersMap, string? fullPath = null)
+        {
+            _analyzersMap = analyzersMap;
+            FullPath = fullPath;
+        }
 
-        public override string FullPath => null;
+        public override string? FullPath { get; }
         public override string Display => nameof(TestAnalyzerReferenceByLanguage);
         public override object Id => Display;
 

src/VisualStudio/Core/Impl/SolutionExplorer/DiagnosticItem/BaseDiagnosticItemSource.cs

@@ -83,8 +83,7 @@ public IEnumerable Items
                     _specificDiagnosticOptions = project.CompilationOptions!.SpecificDiagnosticOptions;
                     _analyzerConfigOptions = project.GetAnalyzerConfigOptions();
 
-                    _diagnosticItems = new BulkObservableCollection<BaseDiagnosticItem>();
-                    _diagnosticItems.AddRange(GetDiagnosticItems(project.Language, project.CompilationOptions, _analyzerConfigOptions));
+                    _diagnosticItems = CreateDiagnosticItems(project.Language, project.CompilationOptions, _analyzerConfigOptions);
 
                     Workspace.WorkspaceChanged += OnWorkspaceChangedLookForOptionsChanges;
                 }
@@ -97,7 +96,7 @@ public IEnumerable Items
             }
         }
 
-        private IEnumerable<BaseDiagnosticItem> GetDiagnosticItems(string language, CompilationOptions options, AnalyzerConfigOptionsResult? analyzerConfigOptions)
+        private BulkObservableCollection<BaseDiagnosticItem> CreateDiagnosticItems(string language, CompilationOptions options, AnalyzerConfigOptionsResult? analyzerConfigOptions)
         {
             // Within an analyzer assembly, an individual analyzer may report multiple different diagnostics
             // with the same ID. Or, multiple analyzers may report diagnostics with the same ID. Or a
@@ -110,7 +109,9 @@ private IEnumerable<BaseDiagnosticItem> GetDiagnosticItems(string language, Comp
 
             Contract.ThrowIfFalse(HasItems);
 
-            return AnalyzerReference.GetAnalyzers(language)
+            var collection = new BulkObservableCollection<BaseDiagnosticItem>();
+            collection.AddRange(
+                AnalyzerReference.GetAnalyzers(language)
                 .SelectMany(a => _diagnosticAnalyzerService.AnalyzerInfoCache.GetDiagnosticDescriptors(a))
                 .GroupBy(d => d.Id)
                 .OrderBy(g => g.Key, StringComparer.CurrentCulture)
@@ -119,7 +120,9 @@ private IEnumerable<BaseDiagnosticItem> GetDiagnosticItems(string language, Comp
                     var selectedDiagnostic = g.OrderBy(d => d, s_comparer).First();
                     var effectiveSeverity = selectedDiagnostic.GetEffectiveSeverity(options, analyzerConfigOptions);
                     return CreateItem(selectedDiagnostic, effectiveSeverity, language);
-                });
+                }));
+
+            return collection;
         }
 
         private void OnWorkspaceChangedLookForOptionsChanges(object sender, WorkspaceChangeEventArgs e)

src/VisualStudio/Core/Test/SolutionExplorer/CpsDiagnosticItemSourceTests.vb

@@ -0,0 +1,51 @@
+' Licensed to the .NET Foundation under one or more agreements.
+' The .NET Foundation licenses this file to you under the MIT license.
+' See the LICENSE file in the project root for more information.
+
+Imports System.Collections.Immutable
+Imports Microsoft.CodeAnalysis
+Imports Microsoft.CodeAnalysis.Diagnostics
+Imports Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces
+Imports Microsoft.CodeAnalysis.Test.Utilities
+Imports Microsoft.Internal.VisualStudio.PlatformUI
+Imports Microsoft.VisualStudio.LanguageServices.Implementation.SolutionExplorer
+Imports Microsoft.VisualStudio.LanguageServices.UnitTests.ProjectSystemShim.Framework
+Imports Microsoft.VisualStudio.Shell
+
+Namespace Microsoft.VisualStudio.LanguageServices.UnitTests.SolutionExplorer
+    <UseExportProvider>
+    Public Class CpsDiagnosticItemSourceTests
+        <Fact, Trait(Traits.Feature, Traits.Features.Diagnostics)>
+        Public Sub AnalyzerHasDiagnostics()
+            Dim workspaceXml =
+                <Workspace>
+                    <Project Language="Visual Basic" CommonReferences="true">
+                    </Project>
+                </Workspace>
+
+            Using workspace = TestWorkspace.Create(workspaceXml)
+                Dim project = workspace.Projects.Single()
+
+                Dim analyzers = New Dictionary(Of String, ImmutableArray(Of DiagnosticAnalyzer))
+
+                ' The choice here of this analyzer to test with is arbitray -- there's nothing special about this
+                ' analyzer versus any other one.
+                analyzers.Add(LanguageNames.VisualBasic, ImmutableArray.Create(Of DiagnosticAnalyzer)(New Microsoft.CodeAnalysis.VisualBasic.UseAutoProperty.VisualBasicUseAutoPropertyAnalyzer()))
+
+                Const analyzerPath = "C:\Analyzer.dll"
+                workspace.OnAnalyzerReferenceAdded(project.Id, New TestAnalyzerReferenceByLanguage(analyzers, analyzerPath))
+
+                Dim source As IAttachedCollectionSource = New CpsDiagnosticItemSource(
+                    workspace,
+                    project.FilePath,
+                    project.Id,
+                    New MockHierarchyItem() With {.CanonicalName = "\net472\analyzerdependency\" + analyzerPath},
+                    New FakeAnalyzersCommandHandler, workspace.GetService(Of IDiagnosticAnalyzerService))
+
+                Assert.True(source.HasItems)
+                Dim diagnostic = Assert.IsAssignableFrom(Of ITreeDisplayItem)(Assert.Single(source.Items))
+                Assert.Contains(IDEDiagnosticIds.UseAutoPropertyDiagnosticId, diagnostic.Text)
+            End Using
+        End Sub
+    End Class
+End Namespace