Fix exception when the list only contains a suggestion mode item

dotnet · Mar 1, 2023 · 1e2ab52 · 1e2ab52
1 parent 894751f
commit 1e2ab52
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Showing 2 changed files with 33 additions and 2 deletions.
diff --git a/src/Features/LanguageServer/Protocol/Handler/Completion/CompletionHandler.cs b/src/Features/LanguageServer/Protocol/Handler/Completion/CompletionHandler.cs
@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Composition;
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Text;
@@ -90,12 +91,15 @@ public CompletionHandler(
                 return null;
 
             var (list, isIncomplete, resultId) = completionListResult.Value;
-            if (list.IsEmpty)
+
+            if (list.ItemsList.Count == 0)
             {
                 return new LSP.VSInternalCompletionList
                 {
                     Items = Array.Empty<LSP.CompletionItem>(),
-                    SuggestionMode = list.SuggestionModeItem != null,
+                    // If we have a suggestion mode item, we just need to keep the list in suggestion mode.
+                    // We don't need to return the suggestion mode item.
+                    SuggestionMode = list.SuggestionModeItem is not null,
                     IsIncomplete = isIncomplete,
                 };
             }

diff --git a/src/Features/LanguageServer/ProtocolUnitTests/Completion/CompletionTests.cs b/src/Features/LanguageServer/ProtocolUnitTests/Completion/CompletionTests.cs
@@ -1361,6 +1361,33 @@ void M()
             Assert.Empty(results.Items);
         }
 
+        [Fact, WorkItem(1755138, "https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1755138")]
+        public async Task TestOnlyHasSuggestionModeItemAsync()
+        {
+            var markup =
+@"using System.Threading.Tasks;
+class A
+{
+    void M()
+    {
+        Task.Run(abcdefg{|caret:|}
+    }
+}";
+            await using var testLspServer = await CreateTestLspServerAsync(markup, s_vsCompletionCapabilities);
+            var completionParams = CreateCompletionParams(
+                testLspServer.GetLocations("caret").Single(),
+                invokeKind: LSP.VSInternalCompletionInvokeKind.Typing,
+                triggerCharacter: "g",
+                triggerKind: LSP.CompletionTriggerKind.TriggerForIncompleteCompletions);
+
+            var document = testLspServer.GetCurrentSolution().Projects.First().Documents.First();
+
+            var results = await RunGetCompletionsAsync(testLspServer, completionParams).ConfigureAwait(false);
+            var list = (LSP.VSInternalCompletionList)results;
+            Assert.Empty(list.Items);
+            Assert.True(list.SuggestionMode);
+        }
+
         internal static Task<LSP.CompletionList> RunGetCompletionsAsync(TestLspServer testLspServer, LSP.CompletionParams completionParams)
         {
             return testLspServer.ExecuteRequestAsync<LSP.CompletionParams, LSP.CompletionList>(LSP.Methods.TextDocumentCompletionName,