test-writer

name	test-writer
description	Write test code. 100% coverage, SSR tests, edge cases. Use when writing tests, adding test coverage.
allowed-tools	Read, Write, Edit, Bash

Test Writer

Writes tests that achieve 100% coverage.

Quick Start

yarn test:spec      # Run a single test
yarn test:coverage  # Check coverage

Core Patterns

1. SSR Test (Required)

it('is safe on server side rendering', () => {
  const result = renderHookSSR.serverOnly(() => useHook());
  expect(result.current).toBeDefined();
});

2. Basic Behavior Test

it('returns expected value', () => {
  const { result } = renderHook(() => useHook(input));
  expect(result.current).toBe(expected);
});

3. Edge Cases

it('handles null/undefined', () => { ... });
it('handles empty values', () => { ... });

4. State Change Test

it('updates when state changes', () => {
  const { result, rerender } = renderHook(({ value }) => useHook(value), {
    initialProps: { value: 'initial' },
  });
  rerender({ value: 'updated' });
  expect(result.current).toBe('updated');
});

Coverage Check

All lines, branches, and functions must have 100% coverage.

References

• details.md - Advanced test patterns