How to Generate Tests Using Cursor

1# .cursorrules (add to existing file)
2
3## Testing Rules
4- Test runner: Vitest (or Jest)
5- Test file naming: {filename}.test.ts next to source file
6- Test structure: describe block per function, it blocks per scenario
7- Coverage targets: statements 100%, branches 100%, functions 100%, lines 100%
8- Always test: happy path, edge cases, error cases, boundary values
9- Mock external dependencies (HTTP, database, file system) — never real I/O
10- Use factory functions for test data, not inline object literals
11- Each test must have exactly one assertion focus (one expect per it block)
12- Include TypeScript types for all mock data

1---
2description: Unit test generation standards
3globs: "**/*.test.ts, **/*.test.tsx, **/*.spec.ts, **/__tests__/**"
4alwaysApply: false
5---
6
7- Import from vitest: describe, it, expect, vi, beforeEach, afterEach
8- Use vi.mock() for module mocking, vi.fn() for function mocks
9- Reset all mocks in beforeEach with vi.clearAllMocks()
10- Test error scenarios with expect(() => fn()).toThrow()
11- Test async errors with expect(fn()).rejects.toThrow()
12- Group tests: describe('functionName', () => { ... })
13- Name pattern: it('should [expected behavior] when [condition]')
14- Always test with undefined, null, empty string, 0, and negative numbers

1// Prompt to type in Cursor Composer (Cmd+I):
2// @src/utils/orderCalculator.ts
3// Write a comprehensive test suite for this file.
4// 1. First, list ALL test cases as comments (happy path, edge cases, errors)
5// 2. Then implement each test case
6// 3. Target 100% branch coverage — test every if/else path
7// 4. Mock any external imports
8// 5. Include tests for: null inputs, empty arrays, negative numbers,
9//    maximum values, and type edge cases
10// 6. Run the tests with: npx vitest run src/utils/orderCalculator.test.ts
11// 7. Fix any failures and re-run until all pass

1// Select a function in your editor, then press Cmd+K and type:
2// Generate a test suite for this function covering:
3// - Happy path with valid inputs
4// - Edge case: empty input, null, undefined
5// - Error case: invalid types, out-of-range values
6// - Boundary: zero, negative, MAX_SAFE_INTEGER
7// Use vitest, mock external deps with vi.mock()

1// Prompt to type in Cursor Chat (Cmd+L):
2// @src/utils/orderCalculator.ts @src/utils/orderCalculator.test.ts
3// Analyze the test coverage for this source file.
4// List every code branch, conditional, and error path that is NOT
5// currently tested. For each gap, provide the exact test case I should
6// add, including the test name and assertion.

1// Prompt to type in Cursor Composer (Cmd+I):
2// @src/types/order.ts @src/types/user.ts
3// Generate a test factory file at src/__tests__/factories.ts
4// Requirements:
5// - Factory function for each type (createMockUser, createMockOrder)
6// - Accept partial overrides: createMockUser({ name: 'Custom' })
7// - Use realistic default values, not 'test' or 'foo'
8// - Auto-increment IDs across calls
9// - Include a reset function for beforeEach blocks