Summary

This PR migrates borp from TypeScript compilation (tsc) to Node.js native type stripping, simplifying the architecture and improving test execution speed.

Breaking Changes

Removed CLI Options

• --no-typescript / -T - No longer needed, type stripping is always used
• --post-compile / -P - No compilation step exists to hook into

Removed Features

• Source map support (not needed with type stripping)
• outDir handling - tests run directly from source
• tsconfig.json project references / --build support

Removed Fixtures

The following fixtures that relied on compilation were removed:

• ts-cjs - no CJS transformation support
• ts-cjs-post-compile - post-compile hook obsolete
• ts-esm-post-compile - post-compile hook obsolete
• ts-esm-source-map - source maps not needed
• src-to-dist - outDir pattern not applicable
• monorepo - project references not supported

Requirements

• Node.js >= 22.6.0 (22.19.0+, 24.x+, or 25.x+ recommended for best type stripping support)

Benefits

• Faster test runs: No compilation step required
• Simpler architecture: ~100 lines of code removed
• Native TypeScript: Uses Node.js built-in type stripping
• Better line numbers: Source maps not needed, original .ts line numbers preserved
• Reduced dependencies: No direct TypeScript dependency needed

Architecture Changes

Simplified Core (lib/run.js)

• Renamed runWithTypeScript → runTests
• Removed TypeScript compiler API usage
• Removed watch mode tsc integration (now uses Node.js --watch)
• Simplified to glob expansion + node:test run()

Updated CLI (borp.js)

• Added Node.js version requirement
• Removed TypeScript-related options
• Fixed ignore patterns for auto-discovery
• Updated coverage handling

Updated Imports

All TypeScript test files now use .ts extensions:

// Before
import { add } from '../src/add.js'

// After  
import { add } from '../src/add.ts'

TypeScript Constraints

Type stripping has some limitations. Code must follow these rules:

• Use type-only imports: import type { Foo } or import { type Foo }
• No enums: Use const objects with as const instead
• No namespaces: Use regular modules
• No parameter properties: Explicitly declare class properties
• File extensions: Import .ts files with .ts extension

See Node.js TypeScript documentation for full details.

Migration Guide for Users

1. Update imports: Change .js to .ts in TypeScript import statements
2. Remove outDir: Tests run from source, not dist/ folder
3. Review code: Ensure no enums, namespaces, or parameter properties
4. Update tsconfig.json: Use noEmit: true for type checking only

CI Updates

Updated test matrix to focus on Node versions with type stripping support:

• Added: 25.x
• Kept: 22.x, 24.x
• Dropped: 18.x, 20.x, 21.x, 23.x

Test Results

• ✅ All 35 tests pass
• ✅ 96.17% statement coverage
• ✅ Verified on Node 22.x, 24.x, and 25.x

Documentation Updates

• Updated README with new TypeScript documentation
• Added migration guide from borp < 1.0
• Updated example project setup
• Added type stripping constraints section