feat: Add Form Error List

packages/css/src/components/form-error-list/README.md

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+<!-- @license CC0-1.0 -->
+
+# Form Error List
+
+Use this component at the top of a page to summarise any errors a user has made.
+When a user makes an error, you must show both a Form Error List and an Error Message above each answer that contains an error.
+
+## Guidelines
+
+- Always show a Form Error List when there is a validation error, even if there’s only one.
+- You must link the errors in the Form Error List to the answer they relate to (see below).
+
+## Linking from the Form Error List to each answer
+
+For questions that require a user to answer using a single field, like a file upload, select, textarea, text input or character count, link to the `id` of that field.
+
+When a user has to enter their answer into multiple fields, such as day, month and year fields, link to the `id` of the first field that contains an error.
+If you do not know which field contains an error, link to the `id` of the first field.
+
+For questions that require a user to select one or more options from a list using Radios or Checkboxes, link to the `id` of the first Radio or Checkbox.
+
+## Where to put the Form Error List
+
+Put the Form Error List at the top of the main container, outside of the `<form>`-tag. If your page includes breadcrumbs or a back link, place it below these, but above the `<h1>`.
+
+## Relevant WCAG requirements
+
+Pay extra attention to these parts:
+
+- [WCAG requirement 1.3.1](https://www.w3.org/TR/WCAG21/#info-and-relationships): the heading level of the Form Error List depends on where in the page it is placed, this may differ per page.
+
+## References
+
+- [Show an error summary above the form - NL Design System](https://www.nldesignsystem.nl/richtlijnen/formulieren/foutmeldingen#zet-een-samenvatting-van-de-foutmeldingen-boven-het-formulier)
+- [Error Summary component - Gov.uk](https://design-system.service.gov.uk/components/error-summary/)

packages/react/src/FormErrorList/FormErrorList.test.tsx

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+import { render, screen } from '@testing-library/react'
+import { createRef } from 'react'
+import { FormErrorList } from './FormErrorList'
+import '@testing-library/jest-dom'
+
+describe('Form error list', () => {
+  const testErrors = [
+    { id: '#', label: 'Vul een geldige datum in (bijvoorbeeld 6 januari 2030).' },
+    { id: '#', label: 'De geldigheidsdatum van uw paspoort moet in de toekomst liggen.' },
+  ]
+
+  it('renders', () => {
+    render(<FormErrorList errors={testErrors} />)
+
+    const component = screen.getByRole('alert')
+
+    expect(component).toBeInTheDocument()
+    expect(component).toBeVisible()
+  })
+
+  it('does not render when there are no errors', () => {
+    render(<FormErrorList errors={[]} />)
+
+    const component = screen.queryByRole('alert')
+
+    expect(component).not.toBeInTheDocument()
+  })
+
+  it('renders a design system BEM class name', () => {
+    render(<FormErrorList errors={testErrors} />)
+
+    const component = screen.getByRole('alert')
+
+    expect(component).toHaveClass('ams-form-error-list')
+  })
+
+  it('renders an additional class name', () => {
+    render(<FormErrorList errors={testErrors} className="extra" />)
+
+    const component = screen.getByRole('alert')
+
+    expect(component).toHaveClass('ams-form-error-list extra')
+  })
+
+  it('renders a list item and link for every error', () => {
+    render(<FormErrorList errors={testErrors} />)
+
+    const listitems = screen.getAllByRole('listitem')
+    const links = screen.getAllByRole('link')
+
+    expect(listitems.length).toBe(2)
+    expect(links.length).toBe(2)
+  })
+
+  it('renders a link with the correct name and href for every error', () => {
+    render(<FormErrorList errors={testErrors} />)
+
+    const link1 = screen.getByRole('link', { name: testErrors[0].label })
+    const link2 = screen.getByRole('link', { name: testErrors[1].label })
+
+    expect(link1).toHaveAttribute('href', testErrors[0].id)
+    expect(link2).toHaveAttribute('href', testErrors[1].id)
+  })
+
+  it('renders a custom heading', () => {
+    render(<FormErrorList errors={testErrors} heading="Testheading" />)
+
+    const component = screen.getByRole('heading', { name: 'Testheading' })
+
+    expect(component).toBeInTheDocument()
+  })
+
+  it('renders the correct heading level', () => {
+    render(<FormErrorList errors={testErrors} headingLevel={4} />)
+
+    const component = screen.getByRole('heading', { level: 4 })
+
+    expect(component).toBeInTheDocument()
+  })
+
+  it('supports ForwardRef in React', () => {
+    const ref = createRef<HTMLDivElement>()
+
+    render(<FormErrorList errors={testErrors} ref={ref} />)
+
+    const component = screen.getByRole('alert')
+
+    expect(ref.current).toBe(component)
+  })
+})

packages/react/src/FormErrorList/FormErrorList.tsx

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+/**
+ * @license EUPL-1.2+
+ * Copyright Gemeente Amsterdam
+ */
+
+import clsx from 'clsx'
+import { forwardRef } from 'react'
+import type { ForwardedRef, HTMLAttributes } from 'react'
+import { Alert } from '../Alert'
+import { HeadingLevel } from '../Heading/Heading'
+import { LinkList } from '../LinkList'
+
+export type FormErrorListProps = {
+  errors: { id: string; label: string }[]
+  heading?: string
+  headingLevel?: HeadingLevel
+} & HTMLAttributes<HTMLDivElement>
+
+export const FormErrorList = forwardRef(
+  (
+    {
+      className,
+      errors,
+      heading = 'Verbeter de fouten voor u verder gaat',
+      headingLevel = 2,
+      ...restProps
+    }: FormErrorListProps,
+    ref: ForwardedRef<HTMLDivElement>,
+  ) => {
+    if (errors.length === 0) return undefined
+
+    return (
+      <Alert
+        {...restProps}
+        className={clsx('ams-form-error-list', className)}
+        headingLevel={headingLevel}
+        ref={ref}
+        role="alert"
+        severity="error"
+        title={heading}
+      >
+        <LinkList>
+          {errors.map(({ id, label }) => (
+            <LinkList.Link href={id} key={`${id}-${label}`}>
+              {label}
+            </LinkList.Link>
+          ))}
+        </LinkList>
+      </Alert>
+    )
+  },
+)
+
+FormErrorList.displayName = 'FormErrorList'

packages/react/src/FormErrorList/README.md

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+<!-- @license CC0-1.0 -->
+
+# React Form Error List component
+
+[Form Error List documentation](../../../css/src/components/form-error-list/README.md)

packages/react/src/FormErrorList/index.ts

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+export { FormErrorList } from './FormErrorList'
+export type { FormErrorListProps } from './FormErrorList'

packages/react/src/index.ts

@@ -4,6 +4,7 @@
  */
 
 /* Append here */
+export * from './FormErrorList'
 export * from './FileInput'
 export * from './Field'
 export * from './Select'

storybook/src/components/FormErrorList/FormErrorList.docs.mdx

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+import { Controls, Markdown, Meta, Primary } from "@storybook/blocks";
+import * as FormErrorListStories from "./FormErrorList.stories.tsx";
+import README from "../../../../packages/css/src/components/form-error-list/README.md?raw";
+
+<Meta of={FormErrorListStories} />
+
+<Markdown>{README}</Markdown>
+
+<Primary />
+
+<Controls />

storybook/src/components/FormErrorList/FormErrorList.stories.tsx

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+/**
+ * @license EUPL-1.2+
+ * Copyright Gemeente Amsterdam
+ */
+
+import { FormErrorList } from '@amsterdam/design-system-react/src'
+import { Meta, StoryObj } from '@storybook/react'
+
+const meta = {
+  title: 'Components/Forms/Form Error List',
+  component: FormErrorList,
+  args: {
+    errors: [
+      { id: '#', label: 'Vul een geldige datum in (bijvoorbeeld 6 januari 2030).' },
+      { id: '#', label: 'De geldigheidsdatum van uw paspoort moet in de toekomst liggen.' },
+    ],
+  },
+} satisfies Meta<typeof FormErrorList>
+
+export default meta
+
+type Story = StoryObj<typeof meta>
+
+export const Default: Story = {}