Address comments.

extensions/ql-vscode/src/common/commands.ts

@@ -367,6 +367,7 @@ export type AllExtensionCommands = BaseCommands &
   QueryEditorCommands &
   ResultsViewCommands &
   QueryHistoryCommands &
+  LanguageSelectionCommands &
   LocalDatabasesCommands &
   DebuggerCommands &
   VariantAnalysisCommands &

extensions/ql-vscode/src/language-context-store.ts

@@ -43,11 +43,15 @@ export class LanguageContextStore extends DisposableObject {
     );
   }
 
+  // shouldInclude should return true if the given language should be included.
+  // That means that either the given language is selected or the "All" option is selected.
   public shouldInclude(language: QueryLanguage | undefined): boolean {
     return this.languageFilter === "All" || this.languageFilter === language;
   }
 
-  public selectedLanguage(language: QueryLanguage | undefined): boolean {
+  // isSelectedLanguage returns true if the given language is selected. If no language
+  // is given then it returns true if the "All" option is selected.
+  public isSelectedLanguage(language: QueryLanguage | undefined): boolean {
     return (
       (this.languageFilter === "All" && language === undefined) ||
       this.languageFilter === language

extensions/ql-vscode/src/language-selection-panel/language-selection-data-provider.ts

@@ -51,12 +51,12 @@ export class LanguageSelectionTreeDataProvider
   public constructor(private readonly languageContext: LanguageContextStore) {
     super();
 
-    this.treeItems = this.createTree(languageContext);
+    this.treeItems = this.createTree();
 
     // If the language context changes, we need to update the tree.
     this.push(
       this.languageContext.onLanguageContextChanged(() => {
-        this.treeItems = this.createTree(languageContext);
+        this.treeItems = this.createTree();
         this.onDidChangeTreeDataEmitter.fire();
       }),
     );
@@ -80,13 +80,11 @@ export class LanguageSelectionTreeDataProvider
     }
   }
 
-  private createTree(
-    languageContext: LanguageContextStore,
-  ): LanguageSelectionTreeViewItem[] {
+  private createTree(): LanguageSelectionTreeViewItem[] {
     return ALL_LANGUAGE_SELECTION_OPTIONS.map((language) => {
       return new LanguageSelectionTreeViewItem(
         language,
-        languageContext.selectedLanguage(language),
+        this.languageContext.isSelectedLanguage(language),
       );
     });
   }

extensions/ql-vscode/src/language-selection-panel/language-selection-panel.ts

@@ -14,6 +14,7 @@ export class LanguageSelectionPanel extends DisposableObject {
     super();
 
     const dataProvider = new LanguageSelectionTreeDataProvider(languageContext);
+    this.push(dataProvider);
 
     const treeView = window.createTreeView("codeQLLanguageSelection", {
       treeDataProvider: dataProvider,

extensions/ql-vscode/test/vscode-tests/no-workspace/language-selection-panel/language-selection-data-provider.test.ts

@@ -40,16 +40,13 @@ describe("LanguageSelectionTreeDataProvider", () => {
           return getLanguageDisplayName(language);
         }),
       ];
-      // Note that the internal order of C# and C / C++ is different from what is shown in the UI.
-      [expectedLanguageNames[1], expectedLanguageNames[2]] = [
-        expectedLanguageNames[2],
-        expectedLanguageNames[1],
-      ];
       const actualLanguagesNames = dataProvider.getChildren().map((item) => {
         return item.label;
       });
 
-      expect(actualLanguagesNames).toEqual(expectedLanguageNames);
+      // Note that the internal order of C# and C / C++ is different from what is shown in the UI.
+      // So we sort to make sure we can compare the two lists.
+      expect(actualLanguagesNames.sort()).toEqual(expectedLanguageNames.sort());
     });
 
     it("default selection is All languages", async () => {