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awesome-copilot/skills/react19-test-patterns/SKILL.md
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Stephen Benjamin 4214189287 fix: repair broken skill references, fence nesting, and invisible unicode (#2568)
While implementing the Agent Plugin v1 spec in https://github.com/stbenjam/skillsaw/pull/483, I used this repository as a canonical real-world source for tests. Along the way its checks surfaced genuine correctness issues worth fixing regardless of tooling:

- Internal links that do not resolve (22): wrong relative paths, links whose targets are runtime output paths rather than bundled files (now inline code), a schemeless external URL parsed as a relative path, and links to files that do not exist (removed).

- Bundled skill files never referenced from their SKILL.md (14): each is now cited from the section where it is used, so nothing ships unreachable from the skill's instructions.

- Unclosed or mis-nested code fences (11): markdown templates embedding code blocks now use four-backtick outer fences so inner fences nest instead of closing the template early and leaking example content as live markdown; also removed stray orphan fences and closed an unterminated block at end of file.

- Invisible unicode (1): removed a zero-width space from a code example, a copy-paste artifact invisible to reviewers.
2026-08-07 02:01:43 +00:00

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name, description
name description
react19-test-patterns Provides before/after patterns for migrating test files to React 19 compatibility, including act() imports, Simulate removal, and StrictMode call count changes.

React 19 Test Migration Patterns

Reference for all test file migrations required by React 19.

Priority Order

Fix test files in this order; each layer depends on the previous:

  1. act import fix first, it unblocks everything else
  2. SimulatefireEvent fix immediately after act
  3. Full react-dom/test-utils cleanup remove remaining imports
  4. StrictMode call counts measure actual, don't guess
  5. Async act wrapping for remaining "not wrapped in act" warnings
  6. Custom render helper verify once per codebase, not per test

1. act() Import Fix

// Before  REMOVED in React 19:
import { act } from 'react-dom/test-utils';

// After:
import { act } from 'react';

If mixed with other test-utils imports:

// Before:
import { act, Simulate, renderIntoDocument } from 'react-dom/test-utils';

// After  split the imports:
import { act } from 'react';
import { fireEvent, render } from '@testing-library/react'; // replaces Simulate + renderIntoDocument

2. Simulate → fireEvent

// Before  Simulate REMOVED in React 19:
import { Simulate } from 'react-dom/test-utils';
Simulate.click(element);
Simulate.change(input, { target: { value: 'hello' } });
Simulate.submit(form);
Simulate.keyDown(element, { key: 'Enter', keyCode: 13 });

// After:
import { fireEvent } from '@testing-library/react';
fireEvent.click(element);
fireEvent.change(input, { target: { value: 'hello' } });
fireEvent.submit(form);
fireEvent.keyDown(element, { key: 'Enter', keyCode: 13 });

3. react-dom/test-utils Full API Map

Old (react-dom/test-utils) New location
act import { act } from 'react'
Simulate fireEvent from @testing-library/react
renderIntoDocument render from @testing-library/react
findRenderedDOMComponentWithTag getByRole, getByTestId from RTL
findRenderedDOMComponentWithClass getByRole or container.querySelector
scryRenderedDOMComponentsWithTag getAllByRole from RTL
isElement, isCompositeComponent Remove not needed with RTL
isDOMComponent Remove

4. StrictMode Call Count Fixes

React 19 StrictMode no longer double-invokes useEffect in development. Spy assertions counting effect calls must be updated.

Strategy always measure, never guess:

# Run the failing test, read the actual count from the error:
npm test -- --watchAll=false --testPathPattern="[filename]" --forceExit 2>&1 | grep -E "Expected|Received"
// Before (React 18 StrictMode  effects ran twice):
expect(mockFn).toHaveBeenCalledTimes(2);  // 1 call × 2 (strict double-invoke)

// After (React 19 StrictMode  effects run once):
expect(mockFn).toHaveBeenCalledTimes(1);
// Render-phase calls (component body)  still double-invoked in React 19 StrictMode:
expect(renderSpy).toHaveBeenCalledTimes(2);  // stays at 2 for render body calls