Add component tests for the Toast system (ToastContext, ToastRegion, Toast) with accessibility assertions

[jaynomyaro]

ummary

Add comprehensive component tests for the Toast system, covering ToastContext, ToastRegion, and Toast behavior, with a strong emphasis on accessibility and user interactions.

These tests ensure toast notifications render correctly, expose proper accessibility semantics, and remain reliable as the notification system evolves.

Problem

The current Toast implementation lacks dedicated component test coverage:

Toast rendering and lifecycle behavior are not comprehensively tested.
Accessibility semantics and ARIA attributes are unverified.
Notification ordering and dismissal flows lack regression protection.
Future changes could unintentionally break screen reader support or keyboard interactions.
There is limited confidence in the Toast system's behavior across different states.
Solution

Introduce a comprehensive test suite covering rendering, interactions, lifecycle management, and accessibility requirements across all Toast components.

Test Coverage
ToastContext

Verify that the context provider correctly manages toast state.

Assertions:

Provides toast creation APIs to consumers.
Adds notifications to state correctly.
Removes notifications when dismissed.
Handles multiple simultaneous toasts.
Cleans up expired notifications.
Maintains deterministic ordering.

Example:

showToast("Saved")
showToast("Copied")

Result:

1. Saved
2. Copied
   ToastRegion

Verify that the toast region renders notifications and exposes appropriate accessibility semantics.

Assertions:

Renders active toasts.
Updates when toast state changes.
Handles empty states gracefully.
Preserves notification ordering.
Removes dismissed notifications.
Accessibility Assertions
Region exposes appropriate landmark semantics.
Screen readers can discover active notifications.
Notification updates are announced properly.
Region labels are accessible.

Example:

expect(region).toHaveAttribute('aria-live');
expect(region).toHaveAttribute('aria-label');
Toast

Verify individual toast behavior and interactions.

Assertions:

Renders title and message content.
Displays optional actions.
Supports dismissal interactions.
Handles auto-dismiss timing.
Preserves state during updates.
Cleans up correctly after removal.
Accessibility Assertions
Live Region Semantics
expect(toast).toHaveAttribute('role', 'status');
expect(toast).toHaveAttribute('aria-live', 'polite');
Keyboard Accessibility

Assertions:

Dismiss buttons are keyboard accessible.
Focusable controls expose accessible names.
Keyboard interaction triggers expected behavior.
Focus management remains predictable during dismissal.
Accessible Names

Assertions:

Action buttons expose accessible labels.
Dismiss controls expose accessible names.
Toast content is announced correctly.
Decorative elements are hidden from assistive technologies.
Lifecycle Tests
Create Toast
↓
Render
↓
Announce
↓
Dismiss / Auto-dismiss
↓
Cleanup

Assertions:

Toasts appear immediately after creation.
Auto-dismiss timers remove notifications correctly.
Manual dismissal cancels pending timers.
Cleanup occurs without leaving stale state.
Edge Cases Covered
Context
No active toasts
Multiple simultaneous notifications
Rapid toast creation and removal
Duplicate notifications
Sequential dismissals
Region
Empty notification state
Single toast
Multiple toasts
Dynamic updates during rendering
Toast
Long messages
Missing optional fields
Action buttons
Manual dismissal
Auto-dismiss expiration
Rapid create/remove cycles
Example Assertions
expect(
screen.getByRole('status')
).toBeInTheDocument();
expect(
screen.getByRole('button', { name: /dismiss/i })
).toBeInTheDocument();
expect(
screen.getByText('Transfer completed')
).toBeVisible();
Testing Benefits
Prevents regressions in notification rendering and lifecycle behavior.
Verifies accessibility requirements for assistive technologies.
Ensures keyboard interactions remain functional.
Improves confidence in the Toast system's state management.
Establishes a strong foundation for future notification enhancements.
Breaking Changes

None.

This PR adds automated component and accessibility tests only and does not modify the runtime behavior of ToastContext, ToastRegion, or Toast.

Closes: Missing component and accessibility test coverage for the Toast system (ToastContext, ToastRegion, and Toast)..Closed #479