RFC: Migrate from tape to vitest by chrisgervang · Pull Request #9966 · visgl/deck.gl

chrisgervang · 2026-01-27T17:01:59Z

Background

This RFC proposes modernizing deck.gl's test infrastructure by replacing tape (assertion framework) + ocular-test (runner) with vitest. The migration would consolidate tooling, improve developer experience, and maintain CLI compatibility.

I'd like to learn about features/workflows maintainers used that I can test against vitest. I primarily used CI tests, which includes node, browser, and render tests.

Change List

Add RFC document at dev-docs/RFCs/proposals/vitest-migration-rfc.md
Proposes phased migration of ~185 test files
Details assertion mapping from tape to vitest
Covers @deck.gl/test-utils updates needed

Note

Low Risk
Low risk because this PR only adds documentation (an RFC) and does not change runtime code, build outputs, or CI behavior.

Overview
Adds a new draft RFC (dev-docs/RFCs/proposals/vitest-migration-rfc.md) proposing a phased migration from tape + ocular-test to vitest, including a Vitest workspace setup (node smoke tests + headless/headed browser runs) and a new/updated yarn command matrix.

The RFC also outlines planned API changes for test files (tape assertions → expect()), a Playwright-based replacement for Puppeteer/BrowserTestDriver in browser/render/interaction tests, and a proposed @deck.gl/test-utils update to use an injectable createSpy with a deprecation timeline for the implicit probe.gl fallback.

^{Written by Cursor Bugbot for commit dc15d7c. This will update automatically on new commits. Configure here.}

coveralls · 2026-01-27T17:11:20Z

coverage: 91.006%. remained the same
when pulling dc15d7c on chr/tape-to-vitest
into 1ecaec5 on master.

felixpalmer

I'm in favour of this migration, not having an easy way to do TDD has long been a pain point.

My worry is that there will be a long tail of specific patterns that we have developed over the years to work with tape which will take time to port to vitest. On the other hand, this sort of migration seems the perfect task for an AI agent to tackle, so it's certainly worth trying.

felixpalmer · 2026-01-28T13:55:38Z

+
+## Open Questions
+
+1. Should we convert test file structure to use `describe`/`it` blocks, or keep flat `test()` calls?


This will already be a huge PR, I would keep the test() calls for now

Agreed. My approach is to vibe code a code mod and that would keep the structure the same, just convert syntax.

felixpalmer · 2026-01-28T13:58:37Z

+## Verification
+
+1. `yarn test-node` - runs unit tests in Node (fast feedback)
+2. `yarn test-browser` - runs ALL tests in Chromium (unit + render + interaction)


When testing I use yarn test browser as I can be more confident that it'll match what CI does. My biggest irritation is how the render tests open a browser window and steals focus. My preference for a fast feedback loop would be to run in the browser, but skipping render tests. Generally I disable render tests for initial testing and then run them when I'm mostly done with a feature

Yeah, that's annoying. Let's have the goal be to make the primary command headless and match between local and CI

Proposal: going forward "yarn test-browser" will always open a browser with a vitest runner UI, and perform all tests including render tests.

To just run the test suite in a headless browser without any browser opening and stealing focus, it'll be yarn test-headless

cursor

Cursor Bugbot has reviewed your changes and found 5 potential issues.

cursor · 2026-01-28T18:55:36Z

+
+**1.1 Install dependencies:**
+```bash
+yarn add -D @vitest/browser @vitest/browser-playwright playwright


Missing core vitest package in installation dependencies

High Severity

Phase 1 installation command only adds browser-specific packages (@vitest/browser, @vitest/browser-playwright, playwright) but omits the core vitest package itself. Since this RFC proposes migrating FROM tape TO vitest, the core vitest package doesn't exist yet and must be included in the installation. Without it, none of the vitest commands in the RFC will work.

chrisgervang · 2026-01-28T18:55:47Z

My worry is that there will be a long tail of specific patterns that we have developed over the years to work with tape which will take time to port to vitest. On the other hand, this sort of migration seems the perfect task for an AI agent to tackle, so it's certainly worth trying.

Ha, exactly! After a few false starts I pointed Conductor and Claude Code to make a idempotent conversion script that fed git show master:... in and output the ported test file. The trick seems to be giving the agent a safe way to iterate forward.. otherwise it gets stuck in a loop of breaking things and uses tonnnns of tokens

chrisgervang · 2026-01-29T09:03:53Z

+**Decision point after discovery:**
+- **Few failures (~10-20%)** → Keep hybrid, rename failures to `.browser.spec.ts`
+- **Many failures (~50%+)** → Fall back to browser-only approach


Trying to run all of the tests in the node environment resulted in a lot of failures (which is not a surprise), so I'm going to instead implement the same test config for node that we have on master - use node for a smoke-test, and browser for all tests.

chrisgervang · 2026-01-29T09:07:39Z

+|---------|-------------|
+| `*.spec.ts` | Default - runs in both environments |
+| `*.browser.spec.ts` | Browser-only (WebGL, real DOM, etc.) |


There are so few node tests that I'm actually going to flip the pattern. Default runs in browser, *.node.spec.ts runs in both.

chrisgervang · 2026-01-29T09:20:28Z

+## Verification
+
+1. `yarn test-node` - runs unit tests in Node (fast feedback)
+2. `yarn test-browser` - runs ALL tests in Chromium (unit + render + interaction)


Proposal: going forward "yarn test-browser" will always open a browser with a vitest runner UI, and perform all tests including render tests.

To just run the test suite in a headless browser without any browser opening and stealing focus, it'll be yarn test-headless

felixpalmer · 2026-02-06T08:46:15Z

Proposal: going forward "yarn test-browser" will always open a browser with a vitest runner UI, and perform all tests including render tests.

To just run the test suite in a headless browser without any browser opening and stealing focus, it'll be yarn test-headless
@chrisgervang will the render tests also work in headless mode?

chrisgervang · 2026-02-06T21:19:38Z

@felixpalmer yup, the headless environment run it all in playwright without stealing focus or opening a browser

Proposes replacing tape (assertions) + ocular-test (runner) with vitest. See dev-docs/RFCs/proposals/vitest-migration-rfc.md for full details. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add vitest workspace configuration (node/browser/headless projects) - Clarify entry points: browser as source of truth, node as smoke test - Add Playwright rationale (required by vitest browser mode) - Expand Phase 4 with discovery mechanism for browser-only tests - Add detailed Phase 5 for snapshot/interaction test migration - Add Verification section with test commands - Update risks table with new considerations Co-Authored-By: Claude <noreply@anthropic.com>

- Add 3-phase deprecation plan (9.3.x → 9.4.x → 10.0.0) - Include migration guide for external consumers - Resolve open question #3 about tape deprecation timeline Co-Authored-By: Claude <noreply@anthropic.com>

- Flip file naming: *.node.spec.ts (node) vs *.spec.ts (browser) - Change to vitest.workspace.ts with defineWorkspace - Add CLI command mapping and matrix tables - Document Phase 4 outcome: ~95% tests need browser - List node smoke tests (2 files) and excluded tests Co-Authored-By: Claude <noreply@anthropic.com>

- Add injectable spy API for framework-agnostic test-utils - Document backward compatibility with lazy probe.gl fallback - Add Phase 5 outcome: browser commands, test runners migrated - Document interaction tests passing, render tests need work - Add Phase 7: future benchmark and size test migration - Update Phase 6 cleanup with specific .ocularrc.js items Co-Authored-By: Claude <noreply@anthropic.com>

- @probe.gl/test-utils is now required (static import in tape.ts) - vitest ^4.0.18 added as optional peer dependency - Note: vitest-only users don't need probe.gl but it's required for 9.x compat Co-Authored-By: Claude <noreply@anthropic.com>

chrisgervang requested review from Pessimistress, felixpalmer and ibgreen January 27, 2026 17:03

felixpalmer approved these changes Jan 28, 2026

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cursor Bot reviewed Jan 28, 2026

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chrisgervang commented Jan 29, 2026

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chrisgervang force-pushed the chr/tape-to-vitest branch from e7c63c4 to 7750fed Compare February 2, 2026 17:00

chrisgervang added this to the v9.2 patch releases milestone Feb 2, 2026

chrisgervang force-pushed the chr/tape-to-vitest branch from a014c9e to bb7a6a5 Compare February 4, 2026 23:07

chrisgervang force-pushed the chr/tape-to-vitest branch from bb7a6a5 to 7119e0f Compare February 7, 2026 00:14

chrisgervang force-pushed the chr/tape-to-vitest branch 2 times, most recently from ed2dece to d2c9f78 Compare February 27, 2026 19:07

chrisgervang and others added 6 commits March 4, 2026 14:30

RFC: Migrate from tape to vitest

767f59e

Proposes replacing tape (assertions) + ocular-test (runner) with vitest. See dev-docs/RFCs/proposals/vitest-migration-rfc.md for full details. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

RFC: Add @deck.gl/test-utils deprecation timeline

bd21cb4

- Add 3-phase deprecation plan (9.3.x → 9.4.x → 10.0.0) - Include migration guide for external consumers - Resolve open question #3 about tape deprecation timeline Co-Authored-By: Claude <noreply@anthropic.com>

chrisgervang force-pushed the chr/tape-to-vitest branch from b213ff8 to dc15d7c Compare March 4, 2026 22:30

chrisgervang merged commit 2edcc0d into master Mar 4, 2026
6 checks passed

chrisgervang deleted the chr/tape-to-vitest branch March 4, 2026 22:51


		## Open Questions

		1. Should we convert test file structure to use `describe`/`it` blocks, or keep flat `test()` calls?

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Missing core vitest package in installation dependencies

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chrisgervang commented Jan 28, 2026

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felixpalmer commented Feb 6, 2026

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chrisgervang commented Jan 27, 2026 •

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