Files
awesome-copilot/skills/react19-test-patterns/SKILL.md
T
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

102 lines
3.1 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
---
name: react19-test-patterns
description: '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. **`Simulate``fireEvent`** 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
```jsx
// Before REMOVED in React 19:
import { act } from 'react-dom/test-utils';
// After:
import { act } from 'react';
```
If mixed with other test-utils imports:
```jsx
// 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
```jsx
// 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:**
```bash
# Run the failing test, read the actual count from the error:
npm test -- --watchAll=false --testPathPattern="[filename]" --forceExit 2>&1 | grep -E "Expected|Received"
```
```jsx
// 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);
```
```jsx
// Render-phase calls (component body) still double-invoked in React 19 StrictMode:
expect(renderSpy).toHaveBeenCalledTimes(2); // stays at 2 for render body calls
```