Creating a test in VTK.js

VTK.js tests use Vitest in browser mode through Playwright. Test files are picked up from Sources/**/test*.js.

Class tests usually live in a test directory next to the class. Shared repository tests live in Sources/Testing/test*.js.

Writing tests

Use Vitest APIs directly:

import { it, expect } from "vitest";

it("validates defaults", () => {
  const instance = vtkMyClass.newInstance();
  expect(instance.getProp1()).toBe("prop1 default value");
});

For rendering tests:

• Use it.skipIf(__VTK_TEST_NO_WEBGL__) for WebGL-specific tests.
• Use it.skipIf(!__VTK_TEST_WEBGPU__) for WebGPU-specific tests.
• Use testUtils.createGarbageCollector() to clean up VTK objects and DOM nodes.
• Use testUtils.compareImages(image, [baseline], testName, tolerance) for baseline image checks.

Running tests

$ npm test
$ npm run test:watch
$ npm run test:firefox
$ npm run test:webgpu
$ npx vitest run Sources/Common/Core/DataArray/test/testDataArray.js

The default local browser is Chromium. test:firefox selects Firefox, and test:webgpu enables the WebGPU test path.

For a local headless run:

$ npx vitest run --browser.headless

For the Vitest UI:

$ npx vitest --ui

Baseline images

Image comparison tests use checked-in PNG baselines next to the test file. To update a baseline, run the test locally, save the image produced by captureNextImage(), replace the baseline PNG, and re-run the test.