Test Setup

[jbmoelker]

User story

As a developer,
I want a test setup and test coverage,
so I can author code without worrying about regression.

Checklist

• Test src/lib/ functions with Vitest; use filesystem & request mocking where needed.
• Test src/blocks/ and src/components/ (where relevant) with Astro container + Vitest
• Test src/pages/ with Playwright (focus on critical features only) and Playwright Axe for accessibility testing.
• Add scripts to package.json with a test:unit and test:e2e.
• Add option to add test to npm run create scripts (see plopfile)
• Run in GitHub Actions step (like the linting steps).
• Document test setup

[jbmoelker]

We've experienced some issues with routing in recent Astro releases. So maybe it's good to have some of our tests covering this.

And probably good practice to start adding tests to our /api/ routes.

Individual blocks, components and partials may be easier to test once Astro container API is available.

[jbmoelker]

The Astro container API is now generally available.

[jbmoelker]

Possible setup to test components. Focus on how to, not what we should and shouldn't test.

src/blocks/Image.test.ts:

import { expect, test } from 'vitest';
import { renderToFragment, renderToString } from '@lib/renderer';
import Image from './Image.astro';

// test using rendered component as a string:
test('Image ...', async () => {
  const result = await renderToString(Image, {
    props: {
      image: {
        url: 'https://example.com/image.jpg',
        alt: 'An image',
        // title: 'A title',
      }
    },
  });

  expect(result).toContain(' alt="An image"');
  expect(result).toContain(' loading="lazy"');
  expect(result).not.toContain('<figcaption ');
  expect(result).not.toContain('</figcaption>');
});

// test using rendered component as a document fragment with DOM methods:
test('Image fragment', async () => {
  const fragment = await renderToFragment(Image, {
    props: {
      image: {
        url: 'https://example.com/image.jpg',
        alt: 'An image',
        // title: 'A title',
      }
    },
  });

  expect(fragment.querySelector('img')?.getAttribute('alt')).toEqual('An image');
  expect(fragment.querySelector('figcaption')).toBeNull();
});

src/lib/renderer.ts (helper)

import type { ContainerRenderOptions } from 'astro/container';
import type { AstroComponentFactory } from 'astro/runtime/server/index.d.ts';
import { experimental_AstroContainer as AstroContainer } from 'astro/container';
import { JSDOM } from 'jsdom';

export async function renderToString(
  component: AstroComponentFactory,
  options?: ContainerRenderOptions
): Promise<string> {
  const container = await AstroContainer.create();
  return container.renderToString(component, options);
}

export async function renderToFragment(
  component: AstroComponentFactory,
  options?: ContainerRenderOptions
): Promise<DocumentFragment> {
  const container = await AstroContainer.create();
  const result = await container.renderToString(component, options);
  return JSDOM.fragment(result);
}