APG Patterns
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Dialog (Modal)

A window overlaid on the primary window, rendering the content underneath inert.

Demo

Basic Dialog

A simple modal dialog with title, description, and close functionality.

Without Description

A dialog with only a title and content.

Open demo only →

Accessibility Features

WAI-ARIA Roles

Role Target Element Description
dialog Dialog container Indicates the element is a dialog window

WAI-ARIA dialog role (opens in new tab)

WAI-ARIA Properties

Attribute Target Element Values Required Description
aria-modal dialog true Yes Indicates this is a modal dialog
aria-labelledby dialog ID reference to title element Yes References the dialog title
aria-describedby dialog ID reference to description No References optional description text

Focus Management

Event Behavior
Dialog opens Focus moves to first focusable element inside the dialog
Dialog closes Focus returns to the element that triggered the dialog
Focus trap Tab/Shift+Tab cycles through focusable elements within the dialog only
Background Content outside dialog is made inert (not focusable or interactive)

Keyboard Support

Key Action
Tab Move focus to next focusable element within dialog. When focus is on the last element, moves to first.
Shift + Tab Move focus to previous focusable element within dialog. When focus is on the first element, moves to last.
Escape Close the dialog and return focus to trigger element

section.additionalNotes

  • The dialog title is required for accessibility and should clearly describe the purpose of the dialog
  • Page scrolling is disabled while the dialog is open
  • Clicking the overlay (background) closes the dialog by default
  • The close button has an accessible label for screen readers

Source Code

Dialog.tsx
import React, {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useId,
  useRef,
  useState,
} from 'react';
import { createPortal } from 'react-dom';

// ============================================================================
// Context
// ============================================================================

interface DialogContextValue {
  dialogRef: React.RefObject<HTMLDialogElement | null>;
  open: () => void;
  close: () => void;
  titleId: string;
  descriptionId: string;
}

const DialogContext = createContext<DialogContextValue | null>(null);

function useDialogContext() {
  const context = useContext(DialogContext);
  if (!context) {
    throw new Error('Dialog components must be used within a DialogRoot');
  }
  return context;
}

// ============================================================================
// DialogRoot
// ============================================================================

export interface DialogRootProps {
  children: React.ReactNode;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
}

export function DialogRoot({
  children,
  defaultOpen = false,
  onOpenChange,
}: DialogRootProps): React.ReactElement {
  const dialogRef = useRef<HTMLDialogElement | null>(null);
  const triggerRef = useRef<HTMLElement | null>(null);
  const instanceId = useId();
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
  }, []);

  // Open on mount if defaultOpen
  useEffect(() => {
    if (mounted && defaultOpen && dialogRef.current) {
      dialogRef.current.showModal();
      onOpenChange?.(true);
    }
  }, [mounted, defaultOpen, onOpenChange]);

  const open = useCallback(() => {
    if (dialogRef.current) {
      const { activeElement } = document;
      triggerRef.current = activeElement instanceof HTMLElement ? activeElement : null;
      dialogRef.current.showModal();
      onOpenChange?.(true);
    }
  }, [onOpenChange]);

  const close = useCallback(() => {
    dialogRef.current?.close();
  }, []);

  // Handle dialog close event (from Escape key or close() call)
  // Note: mounted must be in dependencies to re-run after Dialog component mounts
  useEffect(() => {
    const dialog = dialogRef.current;
    if (!dialog) return;

    const handleClose = () => {
      onOpenChange?.(false);
      triggerRef.current?.focus();
    };

    dialog.addEventListener('close', handleClose);
    return () => dialog.removeEventListener('close', handleClose);
  }, [onOpenChange, mounted]);

  const contextValue: DialogContextValue = {
    dialogRef,
    open,
    close,
    titleId: `${instanceId}-title`,
    descriptionId: `${instanceId}-description`,
  };

  return <DialogContext.Provider value={contextValue}>{children}</DialogContext.Provider>;
}

// ============================================================================
// DialogTrigger
// ============================================================================

export interface DialogTriggerProps extends Omit<
  React.ButtonHTMLAttributes<HTMLButtonElement>,
  'onClick'
> {
  children: React.ReactNode;
}

export function DialogTrigger({
  children,
  className = '',
  ...buttonProps
}: DialogTriggerProps): React.ReactElement {
  const { open } = useDialogContext();

  return (
    <button
      type="button"
      className={`apg-dialog-trigger ${className}`.trim()}
      onClick={open}
      {...buttonProps}
    >
      {children}
    </button>
  );
}

// ============================================================================
// Dialog
// ============================================================================

export interface DialogProps {
  /** Dialog title (required for accessibility) */
  title: string;
  /** Optional description text */
  description?: string;
  /** Dialog content */
  children: React.ReactNode;
  /** Close on overlay click */
  closeOnOverlayClick?: boolean;
  /** Additional CSS class */
  className?: string;
}

export function Dialog({
  title,
  description,
  children,
  closeOnOverlayClick = true,
  className = '',
}: DialogProps): React.ReactElement | null {
  const { dialogRef, close, titleId, descriptionId } = useDialogContext();
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
  }, []);

  const handleDialogClick = useCallback(
    (event: React.MouseEvent<HTMLDialogElement>) => {
      // Close on backdrop click
      if (closeOnOverlayClick && event.target === event.currentTarget) {
        close();
      }
    },
    [closeOnOverlayClick, close]
  );

  // SSR safety
  if (typeof document === 'undefined') return null;
  if (!mounted) return null;

  return createPortal(
    // disable dialog a11y warnings, as only dropdown click. there are alternative keyboard ways to close
    // eslint-disable-next-line jsx-a11y/no-noninteractive-element-interactions, jsx-a11y/click-events-have-key-events
    <dialog
      ref={dialogRef}
      className={`apg-dialog ${className}`.trim()}
      aria-labelledby={titleId}
      aria-describedby={description ? descriptionId : undefined}
      onClick={handleDialogClick}
    >
      <div className="apg-dialog-header">
        <h2 id={titleId} className="apg-dialog-title">
          {title}
        </h2>
        <button
          type="button"
          className="apg-dialog-close"
          onClick={close}
          aria-label="Close dialog"
        >
          <svg
            xmlns="http://www.w3.org/2000/svg"
            width="24"
            height="24"
            viewBox="0 0 24 24"
            fill="none"
            stroke="currentColor"
            strokeWidth="2"
            strokeLinecap="round"
            strokeLinejoin="round"
            aria-hidden="true"
          >
            <line x1="18" y1="6" x2="6" y2="18" />
            <line x1="6" y1="6" x2="18" y2="18" />
          </svg>
        </button>
      </div>
      {description && (
        <p id={descriptionId} className="apg-dialog-description">
          {description}
        </p>
      )}
      <div className="apg-dialog-body">{children}</div>
    </dialog>,
    document.body
  );
}

// ============================================================================
// Exports
// ============================================================================

export default {
  Root: DialogRoot,
  Trigger: DialogTrigger,
  Content: Dialog,
};

Usage

Example
import { DialogRoot, DialogTrigger, Dialog } from './Dialog';

function App() {
  return (
    <DialogRoot onOpenChange={(open) => console.log('Dialog:', open)}>
      <DialogTrigger>Open Dialog</DialogTrigger>
      <Dialog
        title="Dialog Title"
        description="Optional description text"
      >
        <p>Dialog content goes here.</p>
      </Dialog>
    </DialogRoot>
  );
}

API

DialogRoot Props

Prop Type Default Description
children ReactNode required DialogTrigger and Dialog components
defaultOpen boolean false Initial open state
onOpenChange (open: boolean) => void - Callback when open state changes

Dialog Props

Prop Type Default Description
title string required Dialog title (for accessibility)
description string - Optional description text
children ReactNode required Dialog content
closeOnOverlayClick boolean true Close when clicking overlay

Testing

Tests verify APG compliance across keyboard interaction, ARIA attributes, and accessibility requirements. The Dialog component uses a two-layer testing strategy.

Testing Strategy

Unit Tests (Testing Library)

Verify the component's rendered output using framework-specific testing libraries. These tests ensure correct HTML structure and ARIA attributes.

  • ARIA attributes (aria-labelledby, aria-describedby)
  • Escape key closes dialog
  • Focus management on open/close
  • Accessibility via jest-axe

E2E Tests (Playwright)

Verify component behavior in a real browser environment across all frameworks. These tests cover interactions and cross-framework consistency.

  • Modal behavior (showModal, backdrop)
  • Focus trap verification
  • Focus restoration on close
  • Overlay click to close
  • ARIA structure validation in live browser
  • axe-core accessibility scanning
  • Cross-framework consistency checks

Test Categories

High Priority: APG Keyboard Interaction ( Unit + E2E )

Test Description
Escape key Closes the dialog

High Priority: APG ARIA Attributes ( Unit + E2E )

Test Description
role="dialog" Dialog element has dialog role
aria-modal="true" Indicates modal behavior
aria-labelledby References the dialog title
aria-describedby References description (when provided)

High Priority: Focus Management ( Unit + E2E )

Test Description
Initial focus Focus moves to first focusable element on open
Focus restore Focus returns to trigger on close
Focus trap Tab cycling stays within dialog (via native dialog)

Medium Priority: Accessibility ( Unit + E2E )

Test Description
axe violations No WCAG 2.1 AA violations (via jest-axe)

Low Priority: Props & Behavior ( Unit )

Test Description
closeOnOverlayClick Controls overlay click behavior
defaultOpen Initial open state
onOpenChange Callback fires on open/close
className Custom classes are applied

E2E Test Code

e2e/dialog.spec.ts
import { test, expect } from '@playwright/test';
import AxeBuilder from '@axe-core/playwright';

/**
 * E2E Tests for Dialog (Modal) Pattern
 *
 * A window overlaid on the primary content, requiring user interaction.
 * Modal dialogs trap focus and prevent interaction with content outside.
 *
 * Key differences from Alert Dialog:
 * - role="dialog" (not "alertdialog")
 * - Escape key closes the dialog
 * - Has close button (×)
 * - aria-describedby is optional
 * - Initial focus on close button or first focusable element
 *
 * APG Reference: https://www.w3.org/WAI/ARIA/apg/patterns/dialog-modal/
 */

const frameworks = ['react', 'vue', 'svelte', 'astro'] as const;

// ============================================
// Helper Functions
// ============================================

const getDialog = (page: import('@playwright/test').Page) => {
  // Use getByRole which only returns visible elements with the role
  // This works for both native <dialog> (implicit role) and custom role="dialog"
  return page.getByRole('dialog');
};

const openDialog = async (page: import('@playwright/test').Page) => {
  const trigger = page.getByRole('button', { name: /open dialog/i }).first();
  await trigger.click();
  // Wait for dialog to be visible (native <dialog> has implicit role="dialog")
  await getDialog(page).waitFor({ state: 'visible' });
  return trigger;
};

// ============================================
// Framework-specific Tests
// ============================================

for (const framework of frameworks) {
  test.describe(`Dialog (${framework})`, () => {
    test.beforeEach(async ({ page }) => {
      await page.goto(`patterns/dialog/${framework}/demo/`);
      // Wait for the trigger button to be visible (indicates hydration complete)
      await page
        .getByRole('button', { name: /open dialog/i })
        .first()
        .waitFor();
    });

    // ------------------------------------------
    // 🔴 High Priority: APG ARIA Structure
    // ------------------------------------------
    test.describe('APG: ARIA Structure', () => {
      test('has role="dialog"', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        await expect(dialog).toBeVisible();
        await expect(dialog).toHaveRole('dialog');
      });

      test('supports native <dialog> or custom role="dialog"', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const tagName = await dialog.evaluate((el) => el.tagName.toLowerCase());

        // Native <dialog> or a custom element with role="dialog" are both acceptable
        expect(tagName === 'dialog' || (await dialog.getAttribute('role')) === 'dialog').toBe(true);
      });

      test('has aria-modal="true" (for custom dialog) or uses showModal (for native)', async ({
        page,
      }) => {
        await openDialog(page);
        const dialog = getDialog(page);

        const isNative = await dialog.evaluate((el) => el.tagName.toLowerCase() === 'dialog');
        if (isNative) {
          // Native <dialog> opened via showModal() is implicitly modal
          // aria-modal is not required when using showModal()
          const hasOpenAttribute = await dialog.evaluate((el) => el.hasAttribute('open'));
          expect(hasOpenAttribute).toBe(true);
        } else {
          // Custom dialog must have aria-modal="true"
          await expect(dialog).toHaveAttribute('aria-modal', 'true');
        }
      });

      test('is modal (opened via showModal for native dialog)', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        await expect(dialog).toBeVisible();

        const isNative = await dialog.evaluate((el) => el.tagName.toLowerCase() === 'dialog');
        if (isNative) {
          // Verify dialog has 'open' attribute (showModal sets this)
          const hasOpenAttribute = await dialog.evaluate((el) => el.hasAttribute('open'));
          expect(hasOpenAttribute).toBe(true);

          // Verify backdrop exists (showModal() creates ::backdrop)
          const hasBackdrop = await dialog.evaluate((el) => {
            const style = window.getComputedStyle(el, '::backdrop');
            return style.display !== 'none';
          });
          expect(hasBackdrop).toBe(true);
        } else {
          // Custom dialog should have aria-modal="true"
          await expect(dialog).toHaveAttribute('aria-modal', 'true');
        }
      });

      test('has aria-labelledby referencing title', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const labelledbyId = await dialog.getAttribute('aria-labelledby');

        expect(labelledbyId).toBeTruthy();
        const titleElement = page.locator(`[id="${labelledbyId}"]`);
        await expect(titleElement).toBeVisible();

        // Verify it's an actual title element (heading)
        const tagName = await titleElement.evaluate((el) => el.tagName.toLowerCase());
        expect(['h1', 'h2', 'h3', 'h4', 'h5', 'h6']).toContain(tagName);
      });

      test('has aria-describedby when description is provided', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const describedbyId = await dialog.getAttribute('aria-describedby');

        // aria-describedby is optional for Dialog
        if (describedbyId) {
          const descriptionElement = page.locator(`[id="${describedbyId}"]`);
          await expect(descriptionElement).toBeVisible();
        }
      });

      test('has close button with accessible label', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const closeButton = dialog.getByRole('button', { name: /close/i });

        await expect(closeButton).toBeVisible();
      });
    });

    // ------------------------------------------
    // 🔴 High Priority: Keyboard Interaction
    // ------------------------------------------
    test.describe('APG: Keyboard Interaction', () => {
      test('Escape closes the dialog', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        await expect(dialog).toBeVisible();

        await page.keyboard.press('Escape');

        // Dialog should be closed
        await expect(dialog).not.toBeVisible();
      });

      test('Tab moves focus to next element', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);

        // Get all focusable elements in dialog
        const focusableElements = dialog.locator(
          'button:not([disabled]), [tabindex="0"], input:not([disabled]), textarea:not([disabled]), select:not([disabled]), a[href]'
        );
        const count = await focusableElements.count();
        expect(count).toBeGreaterThanOrEqual(1);

        // Focus the first element explicitly
        const first = focusableElements.first();
        await first.focus();
        await expect(first).toBeFocused();

        // Tab should move to next element
        await page.keyboard.press('Tab');

        // If there's more than one focusable element, focus should have moved
        if (count > 1) {
          await expect(focusableElements.nth(1)).toBeFocused();
        }
      });

      test('Tab wraps from last to first element (focus trap)', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);

        // Get all focusable elements in dialog
        const focusableElements = dialog.locator(
          'button:not([disabled]), [tabindex="0"], input:not([disabled]), textarea:not([disabled]), select:not([disabled]), a[href]'
        );
        const count = await focusableElements.count();

        // Tab through all elements plus one more to verify wrap
        for (let i = 0; i <= count; i++) {
          await page.keyboard.press('Tab');
        }

        // Focus should still be within dialog
        const focusedElement = page.locator(':focus');
        const isWithinDialog = await focusedElement.evaluate(
          (el) => el.closest('dialog, [role="dialog"]') !== null
        );
        expect(isWithinDialog).toBe(true);
      });

      test('Shift+Tab moves focus to previous element', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const closeButton = dialog.getByRole('button', { name: /close/i });

        // Click close button to ensure focus is in dialog
        await closeButton.click();
        // Dialog closes on click, so reopen
        await page
          .getByRole('button', { name: /open dialog/i })
          .first()
          .click();
        await getDialog(page).waitFor({ state: 'visible' });

        // Tab once to move focus into dialog
        await page.keyboard.press('Tab');

        // Shift+Tab should move backwards but stay in dialog
        await page.keyboard.press('Shift+Tab');

        // Focus should still be within dialog
        const isWithinDialog = await page.evaluate(() => {
          const focused = document.activeElement;
          return focused?.closest('dialog, [role="dialog"]') !== null;
        });
        expect(isWithinDialog).toBe(true);
      });

      test('Shift+Tab wraps from first to last element', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);

        // Get all focusable elements
        const focusableElements = dialog.locator(
          'button:not([disabled]), [tabindex="0"], input:not([disabled]), textarea:not([disabled]), select:not([disabled]), a[href]'
        );
        const count = await focusableElements.count();

        // Shift+Tab through all elements to test wrap
        for (let i = 0; i <= count; i++) {
          await page.keyboard.press('Shift+Tab');
        }

        // Focus should still be within dialog
        const focusedElement = page.locator(':focus');
        const isWithinDialog = await focusedElement.evaluate(
          (el) => el.closest('dialog, [role="dialog"]') !== null
        );
        expect(isWithinDialog).toBe(true);
      });
    });

    // ------------------------------------------
    // 🔴 High Priority: Focus Management
    // ------------------------------------------
    test.describe('APG: Focus Management', () => {
      test('focuses first focusable element on open', async ({ page }) => {
        await openDialog(page);

        // Focus should be within dialog
        const focusedElement = page.locator(':focus');
        const isWithinDialog = await focusedElement.evaluate(
          (el) => el.closest('dialog, [role="dialog"]') !== null
        );
        expect(isWithinDialog).toBe(true);
      });

      test('returns focus to trigger on close via Escape', async ({ page }) => {
        const trigger = await openDialog(page);

        await page.keyboard.press('Escape');

        // Focus should return to trigger
        await expect(trigger).toBeFocused();
      });

      test('returns focus to trigger on close via close button', async ({ page }) => {
        const trigger = await openDialog(page);

        const dialog = getDialog(page);
        const closeButton = dialog.getByRole('button', { name: /close/i });
        await closeButton.click();

        // Focus should return to trigger
        await expect(trigger).toBeFocused();
      });

      test('traps focus within dialog', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);

        // Get count of focusable elements
        const focusableElements = dialog.locator(
          'button:not([disabled]), [tabindex="0"], input:not([disabled]), textarea:not([disabled]), select:not([disabled]), a[href]'
        );
        const count = await focusableElements.count();

        // Tab many times - focus should never leave dialog
        // First Tab may move focus into dialog, then subsequent Tabs should stay within
        const tabCount = Math.max(count * 3, 10);
        for (let i = 0; i < tabCount; i++) {
          await page.keyboard.press('Tab');
        }

        // After many Tabs, focus should still be within dialog
        const isWithinDialog = await page.evaluate(() => {
          const focused = document.activeElement;
          return focused?.closest('dialog, [role="dialog"]') !== null;
        });
        expect(isWithinDialog).toBe(true);
      });
    });

    // ------------------------------------------
    // 🔴 High Priority: Click Interaction
    // ------------------------------------------
    test.describe('APG: Click Interaction', () => {
      test('clicking close button closes dialog', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        const closeButton = dialog.getByRole('button', { name: /close/i });
        await closeButton.click();

        await expect(dialog).not.toBeVisible();
      });

      test('clicking overlay closes dialog', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        await expect(dialog).toBeVisible();

        // Get viewport size and dialog bounds to find a safe click position outside dialog
        const viewportSize = page.viewportSize();
        const dialogBox = await dialog.boundingBox();

        if (viewportSize && dialogBox) {
          // Find a safe position outside dialog, handling edge cases
          // Try multiple positions: top, left, right, bottom of dialog
          const candidates = [
            // Above dialog (if there's space)
            { x: dialogBox.x + dialogBox.width / 2, y: Math.max(1, dialogBox.y - 20) },
            // Left of dialog (if there's space)
            { x: Math.max(1, dialogBox.x - 20), y: dialogBox.y + dialogBox.height / 2 },
            // Right of dialog (if there's space)
            {
              x: Math.min(viewportSize.width - 1, dialogBox.x + dialogBox.width + 20),
              y: dialogBox.y + dialogBox.height / 2,
            },
            // Below dialog (if there's space)
            {
              x: dialogBox.x + dialogBox.width / 2,
              y: Math.min(viewportSize.height - 1, dialogBox.y + dialogBox.height + 20),
            },
          ];

          // Find first candidate that's outside dialog bounds
          const isOutsideDialog = (x: number, y: number) =>
            x < dialogBox.x ||
            x > dialogBox.x + dialogBox.width ||
            y < dialogBox.y ||
            y > dialogBox.y + dialogBox.height;

          const safePosition = candidates.find((pos) => isOutsideDialog(pos.x, pos.y));

          if (safePosition) {
            await page.mouse.click(safePosition.x, safePosition.y);
          } else {
            // Fallback: click at viewport corner (1,1)
            await page.mouse.click(1, 1);
          }
        } else {
          // Fallback: click at viewport corner
          await page.mouse.click(1, 1);
        }

        // Dialog should close when clicking overlay
        await expect(dialog).not.toBeVisible();
      });
    });

    // ------------------------------------------
    // 🟢 Low Priority: Accessibility
    // ------------------------------------------
    test.describe('Accessibility', () => {
      test('has no axe-core violations', async ({ page }) => {
        await openDialog(page);

        const dialog = getDialog(page);
        await expect(dialog).toBeVisible();

        const results = await new AxeBuilder({ page })
          .include('dialog')
          .disableRules(['color-contrast'])
          .analyze();

        expect(results.violations).toEqual([]);
      });
    });
  });
}

// ============================================
// Cross-framework Consistency Tests
// ============================================

test.describe('Dialog - Cross-framework Consistency', () => {
  test('all frameworks render dialog with role="dialog"', async ({ page }) => {
    for (const framework of frameworks) {
      await page.goto(`patterns/dialog/${framework}/demo/`);
      await page
        .getByRole('button', { name: /open dialog/i })
        .first()
        .waitFor();

      // Open dialog
      const trigger = page.getByRole('button', { name: /open dialog/i }).first();
      await trigger.click();
      await getDialog(page).waitFor({ state: 'visible' });

      const dialog = getDialog(page);
      await expect(dialog).toBeVisible();
      await expect(dialog).toHaveRole('dialog');

      // Close dialog for next iteration
      await page.keyboard.press('Escape');
    }
  });

  test('all frameworks have aria-labelledby', async ({ page }) => {
    for (const framework of frameworks) {
      await page.goto(`patterns/dialog/${framework}/demo/`);
      await page
        .getByRole('button', { name: /open dialog/i })
        .first()
        .waitFor();

      const trigger = page.getByRole('button', { name: /open dialog/i }).first();
      await trigger.click();
      await getDialog(page).waitFor({ state: 'visible' });

      const dialog = getDialog(page);
      const labelledbyId = await dialog.getAttribute('aria-labelledby');
      expect(labelledbyId).toBeTruthy();

      await page.keyboard.press('Escape');
    }
  });

  test('all frameworks close on Escape', async ({ page }) => {
    for (const framework of frameworks) {
      await page.goto(`patterns/dialog/${framework}/demo/`);
      await page
        .getByRole('button', { name: /open dialog/i })
        .first()
        .waitFor();

      const trigger = page.getByRole('button', { name: /open dialog/i }).first();
      await trigger.click();
      await getDialog(page).waitFor({ state: 'visible' });

      const dialog = getDialog(page);
      await expect(dialog).toBeVisible();

      await page.keyboard.press('Escape');
      await expect(dialog).not.toBeVisible();
    }
  });

  test('all frameworks trap focus within dialog', async ({ page }) => {
    for (const framework of frameworks) {
      await page.goto(`patterns/dialog/${framework}/demo/`);
      await page
        .getByRole('button', { name: /open dialog/i })
        .first()
        .waitFor();

      const trigger = page.getByRole('button', { name: /open dialog/i }).first();
      await trigger.click();
      await getDialog(page).waitFor({ state: 'visible' });

      // Tab multiple times
      for (let i = 0; i < 10; i++) {
        await page.keyboard.press('Tab');
      }

      // After many Tabs, focus should still be within dialog
      const isWithinDialog = await page.evaluate(() => {
        const focused = document.activeElement;
        return focused?.closest('dialog, [role="dialog"]') !== null;
      });
      expect(isWithinDialog).toBe(true);

      await page.keyboard.press('Escape');
    }
  });
});

Running Tests

          
            # Run unit tests for Dialog
npm run test -- dialog

# Run E2E tests for Dialog (all frameworks)
npm run test:e2e:pattern --pattern=dialog
          
        

Testing Tools

See testing-strategy.md (opens in new tab) for full documentation.

Dialog.test.tsx
import { render, screen, within } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { axe } from 'jest-axe';
import { describe, expect, it, vi } from 'vitest';
import { DialogRoot, DialogTrigger, Dialog } from './Dialog';

// Test wrapper component
function TestDialog({
  title = 'Test Dialog',
  description,
  closeOnOverlayClick = true,
  defaultOpen = false,
  onOpenChange,
  children = <p>Dialog content</p>,
}: {
  title?: string;
  description?: string;
  closeOnOverlayClick?: boolean;
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
  children?: React.ReactNode;
}) {
  return (
    <DialogRoot defaultOpen={defaultOpen} onOpenChange={onOpenChange}>
      <DialogTrigger>Open Dialog</DialogTrigger>
      <Dialog title={title} description={description} closeOnOverlayClick={closeOnOverlayClick}>
        {children}
      </Dialog>
    </DialogRoot>
  );
}

describe('Dialog', () => {
  // 🔴 High Priority: APG Core Compliance
  describe('APG: Keyboard Interaction', () => {
    it('closes dialog with Escape key', async () => {
      const user = userEvent.setup();
      render(<TestDialog />);

      // Open dialog
      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(screen.getByRole('dialog')).toBeInTheDocument();

      // Close with Escape
      await user.keyboard('{Escape}');
      expect(screen.queryByRole('dialog')).not.toBeInTheDocument();
    });
  });

  describe('APG: ARIA Attributes', () => {
    it('has role="dialog"', async () => {
      const user = userEvent.setup();
      render(<TestDialog />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(screen.getByRole('dialog')).toBeInTheDocument();
    });

    it('has aria-modal="true"', async () => {
      const user = userEvent.setup();
      render(<TestDialog />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(screen.getByRole('dialog')).toHaveAttribute('aria-modal', 'true');
    });

    it('references title with aria-labelledby', async () => {
      const user = userEvent.setup();
      render(<TestDialog title="My Dialog Title" />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      const dialog = screen.getByRole('dialog');
      const titleId = dialog.getAttribute('aria-labelledby');

      expect(titleId).toBeTruthy();
      expect(document.getElementById(titleId!)).toHaveTextContent('My Dialog Title');
    });

    it('references description with aria-describedby when present', async () => {
      const user = userEvent.setup();
      render(<TestDialog description="This is a description" />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      await vi.waitFor(() => {
        const dialog = screen.getByRole('dialog');
        const descriptionId = dialog.getAttribute('aria-describedby');

        expect(descriptionId).toBeTruthy();
        expect(document.getElementById(descriptionId!)).toHaveTextContent('This is a description');
      });
    });

    it('has no aria-describedby when description is absent', async () => {
      const user = userEvent.setup();
      render(<TestDialog />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      const dialog = screen.getByRole('dialog');

      expect(dialog).not.toHaveAttribute('aria-describedby');
    });
  });

  describe('APG: Focus Management', () => {
    it('focuses first focusable element when opened', async () => {
      const user = userEvent.setup();
      render(<TestDialog />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));

      // Focus moves to first focusable element in dialog (Close button)
      await vi.waitFor(() => {
        expect(screen.getByRole('button', { name: 'Close dialog' })).toHaveFocus();
      });
    });

    // Note: Testing autofocus attribute is difficult in jsdom environment
    // because React's autoFocus uses its own focus management, not DOM attributes.
    // Recommended to verify with browser E2E tests (Playwright).

    // Note: Focus restore tests are flaky in jsdom due to showModal() limitations.
    // Covered by E2E tests (Playwright).
    // See: e2e/dialog.spec.ts - Focus Management section
    it.todo('restores focus to trigger when closed');

    // Note: Focus trap is handled by native <dialog> element's showModal().
    // jsdom does not implement showModal()'s focus trap behavior,
    // so these tests should be verified with browser E2E tests (Playwright).
  });

  // 🟡 Medium Priority: Accessibility Validation
  describe('Accessibility', () => {
    it('has no axe violations', async () => {
      const user = userEvent.setup();
      const { container } = render(<TestDialog description="Description" />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));

      const results = await axe(container);
      expect(results).toHaveNoViolations();
    });
  });

  describe('Props', () => {
    it('displays title', async () => {
      const user = userEvent.setup();
      render(<TestDialog title="Custom Title" />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(screen.getByText('Custom Title')).toBeInTheDocument();
    });

    it('displays description', async () => {
      const user = userEvent.setup();
      render(<TestDialog description="Custom Description" />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(screen.getByText('Custom Description')).toBeInTheDocument();
    });

    it('closes on overlay click when closeOnOverlayClick=true', async () => {
      const user = userEvent.setup();
      render(<TestDialog closeOnOverlayClick={true} />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      const dialog = screen.getByRole('dialog');

      // Click dialog element itself (equivalent to overlay)
      await user.click(dialog);
      await vi.waitFor(() => {
        expect(screen.queryByRole('dialog')).not.toBeInTheDocument();
      });
    });

    it('does not close on overlay click when closeOnOverlayClick=false', async () => {
      const user = userEvent.setup();
      render(<TestDialog closeOnOverlayClick={false} />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      const dialog = screen.getByRole('dialog');

      // Click dialog element itself
      await user.click(dialog);
      await vi.waitFor(() => {
        expect(screen.getByRole('dialog')).toBeInTheDocument();
      });
    });

    it('calls onOpenChange when opened and closed', async () => {
      const user = userEvent.setup();
      const onOpenChange = vi.fn();
      render(<TestDialog onOpenChange={onOpenChange} />);

      await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
      expect(onOpenChange).toHaveBeenCalledWith(true);

      // Close with Close button
      await user.click(screen.getByRole('button', { name: 'Close dialog' }));
      await vi.waitFor(() => {
        expect(onOpenChange).toHaveBeenCalledWith(false);
      });
    });

    it('initially displayed when defaultOpen=true', async () => {
      render(<TestDialog defaultOpen={true} />);
      expect(screen.getByRole('dialog')).toBeInTheDocument();
    });
  });

  // 🟢 Low Priority: Extensibility
  describe('HTML Attribute Inheritance', () => {
    it('applies className to dialog', async () => {
      const user = userEvent.setup();
      render(
        <DialogRoot>
          <DialogTrigger>Open</DialogTrigger>
          <Dialog title="Test" className="custom-class">
            Content
          </Dialog>
        </DialogRoot>
      );

      await user.click(screen.getByRole('button', { name: 'Open' }));
      expect(screen.getByRole('dialog')).toHaveClass('custom-class');
    });

    it('applies className to trigger', async () => {
      render(
        <DialogRoot>
          <DialogTrigger className="trigger-class">Open</DialogTrigger>
          <Dialog title="Test">Content</Dialog>
        </DialogRoot>
      );

      expect(screen.getByRole('button', { name: 'Open' })).toHaveClass('trigger-class');
    });
  });
});

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