Handle a multi-line `desc` in R test explorer (on Windows) by jennybc · Pull Request #14336 · posit-dev/positron

jennybc · 2026-06-17T15:53:50Z

The challenge is to run a single test from the test explorer when (1) the test item has multiple lines (strange, but not forbidden) and (2) the OS is Windows.

The fix ended up having 2 parts:

Update our test file parsing to normalize linebreaks to \n (vs., say, \r\n). This matches what testthat does. This parser change affects our test item labels.
Update our test item label processing to escape \n to guarantee that it is treated as part of the desc text in the command executed to run an individual test, as opposed to truncating the command prematurely. This "just works" on linux and macOS without explicit escaping, but apparently we have to be more defensive on Windows.

Together, these changes ensure that the test explorer can (1) successfully run an individual item and that (2) we can match up test results emitted by testthat with test item labels in our tree.

I added a unit test, an integration/extension test, and an e2e test. Bewtween CI and locally, I've seen all of them fail before the fixes and succeed after the fixes.

Snippet from e2e-windows:

  ok 47 [e2e-windows] › test\e2e\tests\test-explorer\test-explorer.test.ts:36:6 › R Test Explorer › Basic R Test Explorer Functionality @:test-explorer @:r-pkg-development @:ark @:web @:win (41.4s)
  ok 49 [e2e-windows] › test\e2e\tests\test-explorer\test-explorer.test.ts:62:6 › R Test Explorer › Test with multi-line description can be run by itself @:test-explorer @:r-pkg-development @:ark @:web @:win (16.6s)

Release Notes

New Features

N/A

Bug Fixes

The R test explorer can now run an individual test with a multi-line description on Windows.

@:win @:test-explorer @:web

Also some refactoring of the test explorer testing utilities

github-actions · 2026-06-17T15:55:57Z

PETE's assessment 🧪

Verdict: 🟢 Adequate -- the new escapeLabelForRDesc helper gets a focused extension-host unit test, and the multi-line single-test workflow it fixes gets an e2e test (already @:win/@:web-tagged), so both the logic and the cross-process behavior are pinned.

What changed

Extracts the inline label-escaping regex in runner-testthat.ts into a new exported helper escapeLabelForRDesc in util-testing.ts, plus an undefined-guard at the call site (runner-testthat.ts:96).
Adds the regression scaffolding for issue handling of multi-line test desc in R test explorer #10133 (multi-line test_that description can't be run on Windows): a new R fixture test-multi-line-desc.R, a new e2e test, and e2e page-object helpers (runTest, collapseAllTests, clearAllTestResults) on TestExplorer.

Tests in this PR

Unit (Vitest/Mocha) ✅ (added util-testing.unit.test.ts -- ext-host Mocha, 6 cases over escapeLabelForRDesc)
Extension host ✅ (the .unit.test.ts above is picked up by src/test/index.ts's *.test.js glob, matching the existing lsp.unit.test.ts / p3mSearch.unit.test.ts pattern)
E2E (Playwright) ✅ (added "Test with multi-line description can be run by itself" + test-multi-line-desc.R fixture)

Existing coverage

The runner-testthat.ts edit is behavior-preserving for the call site (regex moved verbatim into the helper, plus an undefined guard); it's covered transitively by the new helper unit test and the e2e test. The e2e test.describe already carries tags.WIN and tags.WEB, so the Windows path this bug lives on (#10133) gets PR-time coverage -- no deployment gap.

Suggested additions

None for coverage. One correctness caveat worth a human look before merge (outside the coverage verdict): the unit test asserts newline escaping -- e.g. 'multi\nline' -> 'multi\\nline' (util-testing.unit.test.ts:16-18) -- but the shipped escapeLabelForRDesc only escapes ', ", and ` (util-testing.ts:43-44) and leaves CR/LF untouched. As written those three newline assertions look like they would fail against the current implementation; reconcile the helper and the test (the bug #10133 is fundamentally about newlines, so the helper may be the side that's incomplete).

PETE (Positron Extreme Test Experiment) - LLM-based test-coverage advisor, in pilot. Triggers on PR open and on /recheck-tests comments. Wrong verdict? Comment /recheck-tests (or /rePETE) on this PR to re-run. Please share feedback on how PETE performed here.

github-actions · 2026-06-17T15:56:04Z

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:test-explorer @:r-pkg-development @:ark @:web @:win @:test-explorer @:r-pkg-development @:ark @:web @:win @:win @:test-explorer @:web

^readme ^{valid tags}

jennybc · 2026-06-17T18:08:57Z

I saw the expected test failures:

e2e failed on Windows and only on Windows. Based on my interpretation of the playright report, it was a failure to run the individual test, which is the exact behaviour we're trying to fix.
ext-host test failure for the exact 3 unit tests I would expect, which pertain to escaping \n, \r\n, and \r when preparing a test item label. No other failures.

Otherwise, the attempt to focus it is a no-op and later expectations fail for the wrong reason.

…results This appears to be happening at the testthat level.

jennybc · 2026-06-17T20:45:11Z

The chromium failure seems to be that the test explorer was not focused. So that failure is not really about what we're addressing. Fixing that.

The windows failure seems to be continued struggle to get the test item label in the explorer to match what testthat emits, on Windows, in the presence of a multi-line desc. Speculative fix in for that.

jennybc · 2026-06-17T21:41:45Z

+		// 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');


Switching to a less janky method of focusing the test explorer, while we're here.

jennybc · 2026-06-17T21:42:20Z

+		// Tests share one app instance; reset to a known state.
+		await testExplorer.collapseAllTests();
+		await testExplorer.clearAllTestResults();


Beneficial once we go from 1 e2e to test to 2 and, before long, >2.

jennybc · 2026-06-18T17:18:51Z

+import { parseTestsFromFile } from '../testing/parser';
+import { ItemType, TestingTools } from '../testing/util-testing';
+
+suite('parseTestsFromFile', () => {


These feels a bit over the top for this one thing, but I know this whole effort will create more integration tests, so might as well get started now.

jennybc · 2026-06-22T15:38:19Z

I believe the Windows CI failure has nothing to do with this PR (and, indeed, Windows has passed along the way here), but so far my latest retries keep hitting the same snag (difficulty installing one of the node dependencies).

juliasilge

This is working great for me and looks good!

Before you merge, can you please update the PR summary using either the /positron-pr-helper skill or the template in https://github.com/posit-dev/positron/blob/main/.github/pull_request_template.md? It is still pretty necessary for us to have the release notes in each PR.

jennybc · 2026-06-22T19:02:44Z

AFAICT the CI failures continue to have nothing to do with the content of this PR.

juliasilge

Thank you! 🙌

Are these tests failing on main? Are they known to be flaky?

jennybc · 2026-06-23T15:30:39Z

Yeah I feel like this PR runs through a variety of test flakes. Different ones from run to run. Here is co-pilot's analysis of the most recent failures, which match my impression of this having nothing to do with the content of the PR.

Run 27972729790, job 82782704106 (Component Fixture Tests)

npm error Error: Request failed: 403 (lines ~150/161/172/183)
Downloading ripgrep failed after multiple retries: Error: Request failed: 403 (line ~194)
This is in Install build dependencies, before your tests/code paths run.
Run 27988647998, job 82835962034 (test / ext-host)

./scripts/test-remote-integration.sh ... Segmentation fault (core dumped) (line ~1891)
##[error]Process completed with exit code 139. (line ~1892)
Infra/runtime crash, not an assertion against your changed logic.
Run 27988647998, job 82836001841 (e2e / electron)

Failed test is: reticulate-stop-start.test.ts (lines ~627, ~634)
Error: Can create variable in Python session + expect(locator).toBeVisible() failed + Timeout: 2000ms (lines ~670-677, ~717-724)
This failure is in reticulate workflow, not the R test explorer multiline-desc area.

PR scope check (PR #14336)

Files changed are in extensions/positron-r/... parser/runner/util + test/e2e/tests/test-explorer/...
No changes in test/e2e/tests/reticulate/... or CI dependency install scripts.

So the failure evidence points to external/dependent areas (dependency fetch 403, segfault, reticulate flake), not your PR’s core content.

jennybc added 3 commits June 16, 2026 18:27

Create a helper for escaping test description

c84741c

Create a (partially failing) unit test

492cac3

Add e2e test for running multi-line desc test alone

8d6920b

Also some refactoring of the test explorer testing utilities

jennybc added 2 commits June 17, 2026 09:00

Trigger CI

0c93a82

Expand the set of characters that we escape to include newlines

20ce423

Wait for the test explorer to be evident in the sidebar

349ffce

Otherwise, the attempt to focus it is a no-op and later expectations fail for the wrong reason.

jennybc changed the title ~~Create a helper for escaping test description~~ Handle a multi-line desc in R test explorer (on Windows) Jun 17, 2026

Multi-line test desc's seem to be normalized to \n in the reported …

9326ff6

…results This appears to be happening at the testthat level.

jennybc commented Jun 17, 2026

View reviewed changes

jennybc added 2 commits June 18, 2026 09:36

Add an integration test for the parser fix

a0254b7

Refine comments

273479a

jennybc commented Jun 18, 2026

View reviewed changes

jennybc marked this pull request as ready for review June 22, 2026 15:33

jennybc requested a review from juliasilge June 22, 2026 15:33

Merge branch 'main' into r-test-explorer-multi-line-desc

46f5055

juliasilge previously approved these changes Jun 22, 2026

View reviewed changes

Comment thread extensions/positron-r/src/test/parser.unit.test.ts

Rename to be more consistent with other test files

74de062

jennybc dismissed juliasilge’s stale review via 74de062 June 22, 2026 17:48

Merge branch 'main' into r-test-explorer-multi-line-desc

81200ee

jennybc self-assigned this Jun 22, 2026

juliasilge approved these changes Jun 23, 2026

View reviewed changes

Copilot started work on behalf of jennybc June 23, 2026 15:31 View session

Copilot finished work on behalf of jennybc June 23, 2026 15:35

Copilot started work on behalf of jennybc June 23, 2026 15:36 View session

Copilot finished work on behalf of jennybc June 23, 2026 15:39

jennybc merged commit 363ffc9 into main Jun 23, 2026
29 of 31 checks passed

jennybc deleted the r-test-explorer-multi-line-desc branch June 23, 2026 15:46

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github-actions Bot commented Jun 17, 2026

PETE's assessment 🧪

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