walkontable-testing - SKILL.md Agent Skill

name: walkontable-testing path: handsontable/src/3rdparty/walkontable/** description: Use when writing tests for the Walkontable rendering engine - has its own separate test pipeline, runner, and configuration distinct from main Handsontable E2E tests

Testing the Walkontable Rendering Engine

Separate Test Pipeline

Walkontable has its own dedicated test runner. Do NOT run Walkontable tests through the main test:e2e or test:unit commands -- they will not be picked up.

Run command: npm run test:walkontable --prefix handsontable
Test location: src/3rdparty/walkontable/test/

The directory contains two sub-pipelines:

test/spec/ -- E2E-style specs (Jasmine + Puppeteer, same as main E2E but with a separate Rspack config and bootstrap)
test/unit/ -- Unit-style specs for calculators, filters, renderers, and utilities

Writing Tests

The same async/await rules that apply to main E2E tests apply here. All it() callbacks that call rendering APIs must be async, and those API calls must be await-ed.

Tests are organized by subsystem: overlay/, scroll/, selection/, renderer/, table/, viewport.spec.js, etc. Place new tests in the directory that matches the subsystem you are modifying.

What to Cover

Frozen rows and columns: The overlay system (6 overlay types) is the most fragile part of Walkontable. Always include tests with frozen rows/columns to catch overlay positioning and synchronization regressions.
Viewport calculations: Test with various container sizes (small containers that clip content, containers larger than the data, and containers that resize dynamically).
Scroll synchronization: Verify that scrolling the main table keeps frozen overlays aligned. Test both horizontal and vertical scroll.
Large datasets: Include performance-oriented tests with 10k+ rows. Use forEach loops to populate data arrays -- never arr.push(...largeArray).

Common Mistakes

Running Walkontable tests via test:e2e -- they have their own command and will not execute.
Skipping frozen row/column scenarios -- this misses the overlay edge cases where most regressions occur.
Testing only small datasets -- Walkontable bugs often surface at scale.
Modifying Walkontable test bootstrap/Rspack config without verifying that both spec/ and unit/ sub-pipelines still pass.