fix: clear stale R code chunk decorations

src/rmarkdown/index.ts

@@ -36,7 +36,10 @@ export class RMarkdownCodeLensProvider implements vscode.CodeLensProvider {
     private readonly currentCellBottom: vscode.TextEditorDecorationType;
     private onDidChangeTextEditorSelectionHandler: vscode.Disposable | undefined;
 
-    constructor() {
+    constructor(
+        private readonly getVisibleTextEditors: () => readonly vscode.TextEditor[] = () =>
+            vscode.window.visibleTextEditors,
+    ) {
         this.decoration = vscode.window.createTextEditorDecorationType({
             isWholeLine: true,
             backgroundColor: config().get('rmarkdown.chunkBackgroundColor'),
@@ -76,7 +79,7 @@ export class RMarkdownCodeLensProvider implements vscode.CodeLensProvider {
     }
 
     private highlightCurrentChunk(chunks: RMarkdownChunk[], document: vscode.TextDocument) {
-        for (const editor of vscode.window.visibleTextEditors) {
+        for (const editor of this.getVisibleTextEditors()) {
             if (editor.document.uri.toString() === document.uri.toString()) {
                 const lines = document.getText().split(/\r?\n/);
                 const currentLine = editor.selection.active.line;
@@ -102,14 +105,17 @@ export class RMarkdownCodeLensProvider implements vscode.CodeLensProvider {
                         ),
                     );
                     editor.setDecorations(this.currentCellBottom, [currentChunkEnd]);
+                } else {
+                    editor.setDecorations(this.currentCellTop, []);
+                    editor.setDecorations(this.currentCellBottom, []);
                 }
             }
         }
     }
 
     private highlightChunks(chunks: RMarkdownChunk[], document: vscode.TextDocument) {
         const chunkRanges = chunks.map((chunk) => chunk.chunkRange);
-        for (const editor of vscode.window.visibleTextEditors) {
+        for (const editor of this.getVisibleTextEditors()) {
             if (editor.document.uri.toString() === document.uri.toString()) {
                 editor.setDecorations(this.decoration, chunkRanges);
             }

src/test/suite/rmarkdownDecoration.test.ts

@@ -0,0 +1,31 @@
+import * as assert from 'assert';
+import * as vscode from 'vscode';
+
+import { RMarkdownCodeLensProvider } from '../../rmarkdown';
+
+suite('R Markdown chunk decorations', () => {
+    test('clears current chunk borders when the document has no chunks', async () => {
+        const document = {
+            languageId: 'r',
+            uri: vscode.Uri.parse('untitled:rmarkdown-decoration-test'),
+            getText: () => 'x <- 1',
+        } as vscode.TextDocument;
+
+        const decorationCalls: Array<readonly vscode.Range[]> = [];
+        const editor = {
+            document,
+            selection: new vscode.Selection(0, 0, 0, 0),
+            setDecorations: (
+                _decorationType: vscode.TextEditorDecorationType,
+                ranges: readonly vscode.Range[],
+            ) => decorationCalls.push(ranges),
+        } as unknown as vscode.TextEditor;
+        const provider = new RMarkdownCodeLensProvider(() => [editor]);
+        try {
+            provider.provideCodeLenses(document, new vscode.CancellationTokenSource().token);
+            assert.deepStrictEqual(decorationCalls, [[], []]);
+        } finally {
+            provider.dispose();
+        }
+    });
+});