Filter out null values.

src/EditorFeatures/CSharpTest/Structure/CommentStructureTests.cs

@@ -16,7 +16,7 @@ public class CommentTests : AbstractSyntaxStructureProviderTests
     {
         protected override string LanguageName => LanguageNames.CSharp;
 
-        internal override async Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position)
+        internal override async Task<ImmutableArray<BlockSpan>> GetBlockSpansWorkerAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync();
             var trivia = root.FindTrivia(position, findInsideTrivia: true);

src/EditorFeatures/CSharpTest/Structure/MetadataAsSource/InvalidIdentifierStructureTests.cs

@@ -21,7 +21,7 @@ public class InvalidIdentifierStructureTests : AbstractSyntaxStructureProviderTe
         protected override string LanguageName => LanguageNames.CSharp;
         protected override string WorkspaceKind => CodeAnalysis.WorkspaceKind.MetadataAsSource;
 
-        internal override async Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position)
+        internal override async Task<ImmutableArray<BlockSpan>> GetBlockSpansWorkerAsync(Document document, int position)
         {
             var outliningService = document.Project.LanguageServices.GetService<BlockStructureService>();
 

src/EditorFeatures/Test/Structure/AbstractSyntaxNodeStructureProviderTests.cs

@@ -13,7 +13,7 @@ public abstract class AbstractSyntaxNodeStructureProviderTests<TSyntaxNode> : Ab
     {
         internal abstract AbstractSyntaxStructureProvider CreateProvider();
 
-        internal sealed override async Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position)
+        internal sealed override async Task<ImmutableArray<BlockSpan>> GetBlockSpansWorkerAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync(CancellationToken.None);
             var token = root.FindToken(position, findInsideTrivia: true);

src/EditorFeatures/Test/Structure/AbstractSyntaxStructureProviderTests.cs

@@ -2,13 +2,14 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
 using Microsoft.CodeAnalysis.Structure;
 using Microsoft.CodeAnalysis.Text;
+using Roslyn.Utilities;
 using Xunit;
-using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.Editor.UnitTests.Structure
 {
@@ -18,7 +19,13 @@ public abstract class AbstractSyntaxStructureProviderTests
 
         protected virtual string WorkspaceKind => TestWorkspace.WorkspaceName;
 
-        internal abstract Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position);
+        private async Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position)
+        {
+            var spans = await GetBlockSpansWorkerAsync(document, position);
+            return spans.WhereNotNull().ToImmutableArray();
+        }
+
+        internal abstract Task<ImmutableArray<BlockSpan>> GetBlockSpansWorkerAsync(Document document, int position);
 
         protected async Task VerifyBlockSpansAsync(string markupCode, params Tuple<string, string, string, bool, bool>[] expectedRegionData)
         {

src/EditorFeatures/Test/Structure/AbstractSyntaxTriviaStructureProviderTests.cs

@@ -11,7 +11,7 @@ public abstract class AbstractSyntaxTriviaStructureProviderTests : AbstractSynta
     {
         internal abstract AbstractSyntaxStructureProvider CreateProvider();
 
-        internal sealed override async Task<ImmutableArray<BlockSpan>> GetBlockSpansAsync(Document document, int position)
+        internal sealed override async Task<ImmutableArray<BlockSpan>> GetBlockSpansWorkerAsync(Document document, int position)
         {
             var root = await document.GetSyntaxRootAsync();
             var trivia = root.FindTrivia(position, findInsideTrivia: true);

src/EditorFeatures/VisualBasicTest/Structure/CommentStructureTests.vb

@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
             End Get
         End Property
 
-        Friend Overrides Async Function GetBlockSpansAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
+        Friend Overrides Async Function GetBlockSpansWorkerAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
             Dim root = Await document.GetSyntaxRootAsync()
             Dim trivia = root.FindTrivia(position, findInsideTrivia:=True)
 

src/EditorFeatures/VisualBasicTest/Structure/MetadataAsSource/InvalidIdentifierStructureTests.vb

@@ -25,7 +25,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining.Metadata
             End Get
         End Property
 
-        Friend Overrides Async Function GetBlockSpansAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
+        Friend Overrides Async Function GetBlockSpansWorkerAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
             Dim outliningService = document.Project.LanguageServices.GetService(Of BlockStructureService)()
 
             Return (Await outliningService.GetBlockStructureAsync(document, CancellationToken.None)).Spans

src/EditorFeatures/VisualBasicTest/Structure/OverallStructureTests.vb

@@ -15,7 +15,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Outlining
             End Get
         End Property
 
-        Friend Overrides Async Function GetBlockSpansAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
+        Friend Overrides Async Function GetBlockSpansWorkerAsync(document As Document, position As Integer) As Task(Of ImmutableArray(Of BlockSpan))
             Dim outliningService = document.Project.LanguageServices.GetService(Of BlockStructureService)()
 
             Return (Await outliningService.GetBlockStructureAsync(document, CancellationToken.None)).Spans