tsd-lite

tsd-lite

Test your TypeScript types easily.

This is a lighter version of tsd. Slightly reworked codebase allows tsd-lite to be a tool which simply tests your types.

Motivation

While tsd suites perfectly for JavaScript libraries which declare their types in .d.ts files, its usage with monorepos written in TypeScript may become cumbersome. tsd-light is an attempt to address these and similar issues.

Differences from tsd

• tsd-lite performs only type testing without any additional checks or rules.
• Includes only type related assertions: expectAssignable, expectDeprecated, expectType and their counterparts. The printType helper is removed.
• Comes with no default compiler options.
• Reads TypeScript compiler options from the nearest tsconfig.json for each test file (does not read options from package.json).
• tsd-lite is optionally strict. You should add "strict": true to the nearest tsconfig.json (it can be project or test specific) to use strict assertions.
• tsdErrors object is returned if tsd-lite encounters errors while parsing tsconfig.json or if syntax errors are found in the test files.
• @tsd/typescript package is moved to peer dependencies.
• tsd-lite allows only programmatic usage.

Install

yarn add -D tsd-lite @tsd/typescript

Remember to install @tsd/typescript. It is a required peer dependency.

Usage

This library is intended for programmatic use only.

import tsdLite from "tsd-lite";

const { assertionsCount, tsdResults, tsdErrors } = tsdLite(
  "/absolute/path/to/testFile.test.ts"
);

API Reference

tsdLite(testFilePath: string)

The exported function takes fully resolved path to a test file as an argument and returns an object:

{
  assertionsCount: number;
  tsdResults: Array<{
    messageText: string | ts.DiagnosticMessageChain;
    file?: ts.SourceFile;
    start?: number;
  }>;
};

tsd-lite will throw if TS compiler encountered an error while parsing tsconfig.json or found a syntax error while compiling the code.

License

MIT

Changelog

[0.5.0] - 2022-02-04

Fixed

• Breaking: Add assertion logic for expectAssignable and expectType assertions (#17)