diff --git a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerManager.cs b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerManager.cs
index 3598e818cb9be3f52ff5d2f1b768361ff7dd28d9..9bdeda8dd3a84f132fe74a43b8b0d7b0b69c7e2e 100644
--- a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerManager.cs
+++ b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerManager.cs
@@ -19,8 +19,6 @@ namespace Microsoft.CodeAnalysis.Diagnostics
     /// </summary>
     internal partial class AnalyzerManager
     {
-        private readonly object _gate = new object();
-
         // This cache stores the analyzer execution context per-analyzer (i.e. registered actions, supported descriptors, etc.).
         private readonly ImmutableDictionary<DiagnosticAnalyzer, AnalyzerExecutionContext> _analyzerExecutionContextMap;
 
diff --git a/src/EditorFeatures/TestUtilities/Diagnostics/AbstractDiagnosticProviderBasedUserDiagnosticTest.cs b/src/EditorFeatures/TestUtilities/Diagnostics/AbstractDiagnosticProviderBasedUserDiagnosticTest.cs
index 74f29be47c8332367e7356a9fe1bf2a0178e0597..961478d6b0f7b243db72ef8baf5db42fce92937c 100644
--- a/src/EditorFeatures/TestUtilities/Diagnostics/AbstractDiagnosticProviderBasedUserDiagnosticTest.cs
+++ b/src/EditorFeatures/TestUtilities/Diagnostics/AbstractDiagnosticProviderBasedUserDiagnosticTest.cs
@@ -60,17 +60,15 @@ internal virtual (DiagnosticAnalyzer, CodeFixProvider) CreateDiagnosticProviderA
                 document = GetDocumentAndAnnotatedSpan(workspace, out annotation, out span);
             }
 
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, provider))
-            {
-                var diagnostics = await testDriver.GetAllDiagnosticsAsync(provider, document, span);
-                AssertNoAnalyzerExceptionDiagnostics(diagnostics);
+            var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, provider);
+            var diagnostics = await testDriver.GetAllDiagnosticsAsync(provider, document, span);
+            AssertNoAnalyzerExceptionDiagnostics(diagnostics);
 
-                var fixer = providerAndFixer.Item2;
-                var ids = new HashSet<string>(fixer.FixableDiagnosticIds);
-                var dxs = diagnostics.Where(d => ids.Contains(d.Id)).ToList();
-                return await GetDiagnosticAndFixesAsync(
-                    dxs, provider, fixer, testDriver, document, span, annotation, parameters.fixAllActionEquivalenceKey);
-            }
+            var fixer = providerAndFixer.Item2;
+            var ids = new HashSet<string>(fixer.FixableDiagnosticIds);
+            var dxs = diagnostics.Where(d => ids.Contains(d.Id)).ToList();
+            return await GetDiagnosticAndFixesAsync(
+                dxs, provider, fixer, testDriver, document, span, annotation, parameters.fixAllActionEquivalenceKey);
         }
 
         protected async Task TestDiagnosticSeverityAndCountAsync(
diff --git a/src/EditorFeatures/TestUtilities/Diagnostics/AbstractSuppressionDiagnosticTest.cs b/src/EditorFeatures/TestUtilities/Diagnostics/AbstractSuppressionDiagnosticTest.cs
index 3e1afb916f9914b43e74742e7fa73803d562c4cf..65004e640b645c3395a28b4b2e830376583907d7 100644
--- a/src/EditorFeatures/TestUtilities/Diagnostics/AbstractSuppressionDiagnosticTest.cs
+++ b/src/EditorFeatures/TestUtilities/Diagnostics/AbstractSuppressionDiagnosticTest.cs
@@ -71,18 +71,16 @@ private ImmutableArray<Diagnostic> FilterDiagnostics(IEnumerable<Diagnostic> dia
                 document = GetDocumentAndAnnotatedSpan(workspace, out annotation, out span);
             }
 
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, provider, includeSuppressedDiagnostics: IncludeSuppressedDiagnostics))
-            {
-                var fixer = providerAndFixer.Item2;
-                var diagnostics = (await testDriver.GetAllDiagnosticsAsync(provider, document, span))
-                    .Where(d => fixer.CanBeSuppressedOrUnsuppressed(d));
+            var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, provider, includeSuppressedDiagnostics: IncludeSuppressedDiagnostics);
+            var fixer = providerAndFixer.Item2;
+            var diagnostics = (await testDriver.GetAllDiagnosticsAsync(provider, document, span))
+                .Where(d => fixer.CanBeSuppressedOrUnsuppressed(d));
 
-                var filteredDiagnostics = FilterDiagnostics(diagnostics);
+            var filteredDiagnostics = FilterDiagnostics(diagnostics);
 
-                var wrapperCodeFixer = new WrapperCodeFixProvider(fixer, filteredDiagnostics.Select(d => d.Id));
-                return await GetDiagnosticAndFixesAsync(
-                    filteredDiagnostics, provider, wrapperCodeFixer, testDriver, document, span, annotation, parameters.fixAllActionEquivalenceKey);
-            }
+            var wrapperCodeFixer = new WrapperCodeFixProvider(fixer, filteredDiagnostics.Select(d => d.Id));
+            return await GetDiagnosticAndFixesAsync(
+                filteredDiagnostics, provider, wrapperCodeFixer, testDriver, document, span, annotation, parameters.fixAllActionEquivalenceKey);
         }
     }
 }
diff --git a/src/EditorFeatures/TestUtilities/Diagnostics/DiagnosticProviderTestUtilities.cs b/src/EditorFeatures/TestUtilities/Diagnostics/DiagnosticProviderTestUtilities.cs
index 8623b43312781c2766f2a26a286737a21f3e77e8..7f385fca2dd18db48a1e2bef6e4f97ef76c8dbd2 100644
--- a/src/EditorFeatures/TestUtilities/Diagnostics/DiagnosticProviderTestUtilities.cs
+++ b/src/EditorFeatures/TestUtilities/Diagnostics/DiagnosticProviderTestUtilities.cs
@@ -12,18 +12,14 @@ public static class DiagnosticProviderTestUtilities
     {
         public static async Task<IEnumerable<Diagnostic>> GetAllDiagnosticsAsync(DiagnosticAnalyzer workspaceAnalyzerOpt, Document document, TextSpan span, Action<Exception, DiagnosticAnalyzer, Diagnostic> onAnalyzerException = null, bool logAnalyzerExceptionAsDiagnostics = false, bool includeSuppressedDiagnostics = false)
         {
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics))
-            {
-                return await testDriver.GetAllDiagnosticsAsync(workspaceAnalyzerOpt, document, span);
-            }
+            var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics);
+            return await testDriver.GetAllDiagnosticsAsync(workspaceAnalyzerOpt, document, span);
         }
 
         public static async Task<IEnumerable<Diagnostic>> GetAllDiagnosticsAsync(DiagnosticAnalyzer workspaceAnalyzerOpt, Project project, Action<Exception, DiagnosticAnalyzer, Diagnostic> onAnalyzerException = null, bool logAnalyzerExceptionAsDiagnostics = false, bool includeSuppressedDiagnostics = false)
         {
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics))
-            {
-                return await testDriver.GetAllDiagnosticsAsync(workspaceAnalyzerOpt, project);
-            }
+            var testDriver = new TestDiagnosticAnalyzerDriver(project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics);
+            return await testDriver.GetAllDiagnosticsAsync(workspaceAnalyzerOpt, project);
         }
 
         public static async Task<IEnumerable<Diagnostic>> GetAllDiagnosticsAsync(DiagnosticAnalyzer workspaceAnalyzerOpt, Solution solution, Action<Exception, DiagnosticAnalyzer, Diagnostic> onAnalyzerException = null, bool logAnalyzerExceptionAsDiagnostics = false, bool includeSuppressedDiagnostics = false)
@@ -40,18 +36,14 @@ public static async Task<IEnumerable<Diagnostic>> GetAllDiagnosticsAsync(Diagnos
 
         public static async Task<IEnumerable<Diagnostic>> GetDocumentDiagnosticsAsync(DiagnosticAnalyzer workspaceAnalyzerOpt, Document document, TextSpan span, Action<Exception, DiagnosticAnalyzer, Diagnostic> onAnalyzerException = null, bool logAnalyzerExceptionAsDiagnostics = false, bool includeSuppressedDiagnostics = false)
         {
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics))
-            {
-                return await testDriver.GetDocumentDiagnosticsAsync(workspaceAnalyzerOpt, document, span);
-            }
+            var testDriver = new TestDiagnosticAnalyzerDriver(document.Project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics);
+            return await testDriver.GetDocumentDiagnosticsAsync(workspaceAnalyzerOpt, document, span);
         }
 
         public static async Task<IEnumerable<Diagnostic>> GetProjectDiagnosticsAsync(DiagnosticAnalyzer workspaceAnalyzerOpt, Project project, Action<Exception, DiagnosticAnalyzer, Diagnostic> onAnalyzerException = null, bool logAnalyzerExceptionAsDiagnostics = false, bool includeSuppressedDiagnostics = false)
         {
-            using (var testDriver = new TestDiagnosticAnalyzerDriver(project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics))
-            {
-                return await testDriver.GetProjectDiagnosticsAsync(workspaceAnalyzerOpt, project);
-            }
+            var testDriver = new TestDiagnosticAnalyzerDriver(project, workspaceAnalyzerOpt, onAnalyzerException, logAnalyzerExceptionAsDiagnostics, includeSuppressedDiagnostics);
+            return await testDriver.GetProjectDiagnosticsAsync(workspaceAnalyzerOpt, project);
         }
     }
 }
diff --git a/src/EditorFeatures/TestUtilities/Diagnostics/TestDiagnosticAnalyzerDriver.cs b/src/EditorFeatures/TestUtilities/Diagnostics/TestDiagnosticAnalyzerDriver.cs
index 476d6babe94abb04767d1e1d472277a1e02af16a..b04337867dbd4ccab8a6314f0bc07574a9f22b8b 100644
--- a/src/EditorFeatures/TestUtilities/Diagnostics/TestDiagnosticAnalyzerDriver.cs
+++ b/src/EditorFeatures/TestUtilities/Diagnostics/TestDiagnosticAnalyzerDriver.cs
@@ -14,7 +14,7 @@
 
 namespace Microsoft.CodeAnalysis.UnitTests.Diagnostics
 {
-    public class TestDiagnosticAnalyzerDriver : IDisposable
+    public class TestDiagnosticAnalyzerDriver
     {
         private readonly ImmutableArray<DiagnosticAnalyzer> _workspaceAnalyzers;
         private readonly TestDiagnosticAnalyzerService _diagnosticAnalyzerService;
@@ -113,9 +113,5 @@ public Task<IEnumerable<Diagnostic>> GetProjectDiagnosticsAsync(DiagnosticAnalyz
         {
             return GetDiagnosticsAsync(workspaceAnalyzerOpt, null, default(TextSpan), project, getDocumentDiagnostics: false, getProjectDiagnostics: true);
         }
-
-        public void Dispose()
-        {
-        }
     }
 }