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walkontable-testing

Testing & Quality
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Use when writing tests for the Walkontable rendering engine - has its own separate test pipeline, runner, and configuration distinct from main Handsontable E2E tests

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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.
  • Turning on the uniform-size flags (rowHeightsUniform/columnWidthsUniform) in a bare Walkontable spec and then asserting scrollbar-dependent row/column counts: the bare harness overflows content without rendering a real scrollbar, while the single-pass layout snapshot predicts one — so predicted and measured diverge there. Assert the snapshot booleans directly, or use a fixture that renders a real scrollbar; don't compare snapshot-predicted scrollbars/counts against the bare DOM.