# Testing & Quality

SvGrid ships with a comprehensive automated test suite. This page is the honest accounting of what we test, what we don't, and where coverage stands today.

Headline numbers (v1.0)

92.2% line coverage on the testable surface (pnpm --filter sv-grid-community test:lib)

Run the suite locally:

pnpm test            # alias for: pnpm --filter sv-grid-community test:lib
pnpm test:types      # svelte-check on every package

The full coverage report lands in packages/sv-grid-community/coverage/index.html.

What's measured

The testable surface is the headless engine, helpers, and pure logic functions:

• core.ts (createSvGrid, row models, sortFns, filterFns) - ≥ 89% lines
• a11y.ts (ARIA prop builders) - 100% lines
• keyboard.ts (intent + next-cell math) - 100% lines
• cell-formatting.ts (locale / currency / percent / date helpers) - 100% lines
• editors/cell-editors.ts (parseEditorValue for every editor type) - 100% lines
• filtering/excel-filters.ts (every Excel-style operator + edge cases) - 100% lines
• render-component.ts (renderSnippet / renderComponent factories) - 100% lines
• subscribe.ts (store subscription + shallow-compare) - 100% lines
• virtualization/* - ≥ 86% lines

What's measured separately

Two files are tested via behavioral mount tests rather than line coverage because their branches depend on real browser layout (offsetWidth, scroll dimensions, ResizeObserver fires) that jsdom returns as zero:

• SvGrid.svelte - the 4000-line render component. Covered by 60+ behavioral mount tests across svgrid.behavior.test.ts, svgrid.interaction.test.ts, and svgrid.api.test.ts. Each test mounts the real <SvGrid /> in jsdom and exercises a specific feature: sort, filter, pagination, inline editing, cell selection, grouping, row selection, column add/remove, keyboard navigation, etc.
• sv-grid-scrollbar.ts - a custom element that paints scrollbar glyphs from layout measurements. Its paint loop runs in a real browser; jsdom can't exercise it.

What's excluded

The coverage report excludes:

• SvGrid.svelte (covered behaviorally - see above)
• FlexRender.svelte (covered by flex-render.test.ts + every SvGrid mount)
• sv-grid-scrollbar.ts (custom element)
• static-functions.ts (pure re-exports)
• createGridState.svelte.ts (downstream-adapter thin layer)
• test-fixtures/**, test-setup.ts, **/*.test.ts, **/*.d.ts

The exclusion list is part of packages/sv-grid-community/vite.config.ts and is documented inline with the reasoning for each entry.

Test files

Total: 168 tests across 14 test files.

Quality controls beyond unit tests

• TypeScript strict mode across both packages. pnpm test:types must pass on every PR (currently 0 errors / 0 warnings).
• ESLint at pnpm lint, with the Svelte plugin.
• Publint at pnpm --filter sv-grid-community test:build checks the published exports map.
• CSP-strict runtime: no eval, no new Function, no inline scripts. Demo 16-csp-compliant includes a runtime self-check.
• SSR snapshot: demo 19-ssr proves the grid renders meaningful HTML before hydration.
• Accessibility contracts: a11y.contract.test.ts asserts that root, row, header, and cell prop builders produce a consistent ARIA tree.
• Mount-based behavioral tests mount the real <SvGrid /> in jsdom with polyfilled ResizeObserver / IntersectionObserver / scrollIntoView and exercise the imperative API end-to-end.

How to contribute a test

1. Pick a behavior you want to lock down. Bias toward "user does X, grid does Y" over "function Z returns W".
2. If the behavior involves the rendered DOM, mount the component using the pattern in svgrid.api.test.ts:

   import { mount, unmount } from 'svelte'
   import SvGrid from './SvGrid.svelte'
   
   const target = document.createElement('div')
   document.body.appendChild(target)
   const app = mount(SvGrid, {
     target,
     props: { data, columns, features, onApiReady: (a) => { api = a } },
   })
   // exercise + assert
   unmount(app)
   

3. If the behavior is pure (a row model, a sort comparator, an a11y prop builder), add to one of the existing unit-test files.
4. Run pnpm --filter sv-grid-community exec vitest run <file> to iterate fast.
5. Open the PR; include the before/after coverage delta in the description.

CI

The deploy workflow (.github/workflows/deploy-website.yml) currently builds the library and the website. The next step is to add a Test workflow that runs pnpm test + pnpm test:types on every PR and posts the coverage delta as a comment.