Handle a multi-line desc in R test explorer (on Windows)

extensions/positron-r/resources/testing/r.pkg.test.explorer.fixture/tests/testthat/test-multi-line-desc.R

@@ -0,0 +1,4 @@
+test_that("test_that with a
+multi-line description passes", {
+  expect_equal(2 * 2, 4)
+})

extensions/positron-r/src/test/util-testing.unit.test.ts

@@ -0,0 +1,24 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (C) 2026 Posit Software, PBC. All rights reserved.
+ *  Licensed under the Elastic License 2.0. See LICENSE.txt for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as assert from 'assert';
+import { escapeLabelForRDesc } from '../testing/util-testing';
+
+suite('escapeLabelForRDesc', () => {
+	// Labels arrive LF-normalized from the parser; the escaper turns a multi-line
+	// description's newline into the `\n` escape so the R command stays one line (#10133).
+	const cases: Record<string, [input: string, expected: string]> = {
+		'leaves a plain label untouched': ['plain label', 'plain label'],
+		'escapes single quotes': ['it\'s fine', 'it\\\'s fine'],
+		'escapes double quotes and backticks': ['a "b" `c`', 'a \\"b\\" \\`c\\`'],
+		'escapes a LF newline': ['multi\nline', 'multi\\nline'],
+	};
+
+	for (const [name, [input, expected]] of Object.entries(cases)) {
+		test(name, () => {
+			assert.strictEqual(escapeLabelForRDesc(input), expected);
+		});
+	}
+});

extensions/positron-r/src/testing/parser.ts

@@ -220,8 +220,11 @@ function processCapture(
 ): Match {
 	return {
 		functionName: captureFunction.node.text,
-		// we start at 1 and end at (length - 1) because we don't want the surrounding quotes
-		desc: captureDesc.node.text.substring(1, captureDesc.node.text.length - 1),
+		// We start at 1 and end at (length - 1) because we don't want the surrounding
+		// quotes. We normalize CRLF/CR to LF so a multi-line description matches the desc
+		// testthat reports: it reads test files via brio::read_lines, which strips the CR.
+		// This keeps our test-item IDs and single-test `desc=` runs in sync on Windows (#10133).
+		desc: captureDesc.node.text.substring(1, captureDesc.node.text.length - 1).replace(/\r\n?/g, '\n'),
 		startPos: toVSCodePosition(captureCall.node.startPosition),
 		endPos: toVSCodePosition(captureCall.node.endPosition),
 		topLevel: captureCall.node.parent && captureCall.node.parent.type === 'program'

extensions/positron-r/src/testing/runner-testthat.ts

@@ -10,7 +10,7 @@ import split2 from 'split2';
 import { LOGGER } from '../extension';
 import { checkInstalled, getLocale } from '../session';
 import { EXTENSION_ROOT_DIR } from '../constants';
-import { ItemType, TestingTools, encodeNodeId } from './util-testing';
+import { ItemType, TestingTools, encodeNodeId, escapeLabelForRDesc } from './util-testing';
 import { TestResult } from './reporter';
 import { parseTestsFromFile } from './parser';
 import { RSessionManager } from '../session-manager';
@@ -93,7 +93,7 @@ export async function runThatTest(
 	testPath = testPath.replace(/\\/g, '/');
 
 	const devtoolsMethod = testType === ItemType.Directory ? 'test' : 'test_active_file';
-	const escapedLabel = test?.label.replace(/(['"`])/g, '\\$1');
+	const escapedLabel = test?.label === undefined ? undefined : escapeLabelForRDesc(test.label);
 	const descInsert = isSingleTest ? ` desc = '${escapedLabel || '<all tests>'}', ` : '';
 	const devtoolsCall =
 		`devtools::load_all('${testReporterPath}');` +

extensions/positron-r/src/testing/util-testing.ts

@@ -33,6 +33,21 @@ export function encodeNodeId(
 			: testFile;
 }
 
+/**
+ * Escape a test label for use as the `desc` argument when running a single test
+ * via R. The label is embedded in an R single-quoted string literal, which is
+ * itself inside a double-quoted shell `-e` argument, so embedded quotes and
+ * backticks must be escaped. A multi-line description's newline is escaped to
+ * `\n` so the shell command stays on one line and R reconstructs the newline. The
+ * label is already LF-normalized when parsed (see parser.ts), matching what R
+ * stores; a raw newline would otherwise truncate the command on Windows (#10133).
+ */
+export function escapeLabelForRDesc(label: string): string {
+	return label
+		.replace(/(['"`])/g, '\\$1')
+		.replace(/\n/g, '\\n');
+}
+
 export interface TestParser {
 	(testingTools: TestingTools, file: vscode.TestItem): Promise<void>;
 }

test/e2e/infra/workbench.ts

@@ -142,7 +142,7 @@ export class Workbench {
 		this.terminal = new Terminal(code, this.quickaccess);
 		this.viewer = new Viewer(code, this.contextMenu);
 		this.editor = new Editor(code);
-		this.testExplorer = new TestExplorer(code);
+		this.testExplorer = new TestExplorer(code, this.quickaccess);
 		this.outline = new Outline(code, this.quickaccess);
 		this.extensions = new Extensions(code, this.quickaccess);
 		this.settings = new UserSettings(code, this.hotKeys);

test/e2e/pages/testExplorer.ts

@@ -4,6 +4,8 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { expect } from '@playwright/test';
+import { Code } from '../infra/code';
+import { QuickAccess } from './quickaccess';
 import { Explorer } from './explorer';
 
 const TEST_EXPLORER_ICON = '.composite-bar .codicon-test-view-icon';
@@ -13,11 +15,23 @@ const TEST_EXPLORER_ICON = '.composite-bar .codicon-test-view-icon';
  */
 export class TestExplorer extends Explorer {
 
+	constructor(code: Code, private quickaccess: QuickAccess) {
+		super(code);
+	}
+
 	async openTestExplorer(): Promise<void> {
-		const locator = this.code.driver.currentPage.locator(TEST_EXPLORER_ICON);
-		await locator.waitFor({ state: 'attached' });
-		await locator.waitFor({ state: 'visible' });
-		await locator.click();
+		// The view container's activity-bar icon appears once test discovery has
+		// populated it; wait for that before focusing, or the command no-ops.
+		await this.code.driver.currentPage.locator(TEST_EXPLORER_ICON).waitFor({ state: 'visible' });
+		await this.quickaccess.runCommand('workbench.view.testing.focus');
+	}
+
+	async collapseAllTests(): Promise<void> {
+		await this.quickaccess.runCommand('testing.collapseAll');
+	}
+
+	async clearAllTestResults(): Promise<void> {
+		await this.quickaccess.runCommand('testing.clearTestResults');
 	}
 
 	async expectTestItems(labels: string[]): Promise<void> {
@@ -31,6 +45,13 @@ export class TestExplorer extends Explorer {
 		await this.code.driver.currentPage.locator('.composite.title').getByLabel('Run Tests', { exact: true }).click();
 	}
 
+	async runTest(label: string): Promise<void> {
+		const tree = this.code.driver.currentPage.locator('.test-explorer');
+		const row = tree.locator('.monaco-list-row', { hasText: label });
+		await row.hover();
+		await row.getByLabel('Run Test', { exact: true }).click();
+	}
+
 	async expandAllTests(): Promise<void> {
 		const tree = this.code.driver.currentPage.locator('.test-explorer');
 		const collapsed = tree.locator('.monaco-list-row[aria-expanded="false"]');

test/e2e/tests/test-explorer/test-explorer.test.ts

@@ -23,15 +23,19 @@ test.describe('R Test Explorer', { tag: [tags.TEST_EXPLORER, tags.R_PKG_DEVELOPM
 		copyFixtureFolder(source, destination);
 	});
 
-	test('Basic R Test Explorer Functionality', async function ({ app, openFolder }) {
+	test.beforeEach(async function ({ app, openFolder }) {
 		const { testExplorer, sessions } = app.workbench;
-
-		// Open the test fixture folder
 		await openFolder(FIXTURE_NAME);
-
-		// Open the test explorer, start R session, and run tests
 		await testExplorer.openTestExplorer();
+		// Tests share one app instance; reset to a known state.
+		await testExplorer.collapseAllTests();
+		await testExplorer.clearAllTestResults();
 		await sessions.start('r');
+	});
+
+	test('Basic R Test Explorer Functionality', async function ({ app }) {
+		const { testExplorer } = app.workbench;
+
 		await testExplorer.expectTestItems(['test-test-that.R', 'test-describe-it.R']);
 		await testExplorer.runAllTests();
 
@@ -53,4 +57,16 @@ test.describe('R Test Explorer', { tag: [tags.TEST_EXPLORER, tags.R_PKG_DEVELOPM
 		await testExplorer.expectTestStatus('test_that number 1 passes', 'Passed');
 		await testExplorer.expectTestStatus('test_that number 2 fails', 'Failed');
 	});
+
+	// https://github.com/posit-dev/positron/issues/10133
+	test('Test with multi-line description can be run by itself', async function ({ app }) {
+		const { testExplorer } = app.workbench;
+		const MULTI_LINE_LABEL = 'test_that with a multi-line description passes';
+
+		await testExplorer.expectTestItems(['test-multi-line-desc.R']);
+		await testExplorer.expandAllTests();
+
+		await testExplorer.runTest(MULTI_LINE_LABEL);
+		await testExplorer.expectTestStatus(MULTI_LINE_LABEL, 'Passed', 60000);
+	});
 });