tsd: Check TypeScript Type Definitions

tsd is a utility designed for testing TypeScript type definitions, enabling developers to verify the correctness of their `.d.ts` files. The current stable version is 0.33.0, and the project maintains a relatively frequent release cadence, often updating to support newer TypeScript versions shortly after their release. It distinguishes itself by performing static analysis on `.test-d.ts` files, interpreting special assertion functions like `expectType`, `expectError`, and `expectAssignable` to check type compatibility without executing runtime code. This approach ensures that your type definitions accurately reflect your module's API and behavior, catching potential type-related regressions before they manifest as runtime errors or incorrect IDE IntelliSense. tsd is primarily used via its CLI, which automatically discovers project `package.json`, main type definition files, and test files within a configured directory.