TS Expected Errors Validator

Since ts-expect-error does not have the ability to specify only the errors that we want to ignore, and instead suppresses all errors, it makes managing errors more challenging. This package provides a command-line tool to validate expected TypeScript errors with the main goal of making error management easier.

Installation

Install the package:

yarn add -D ts-expect-error-validator

An example of usage:

class User {
   // Specify only a TS code for validation
   // @ts-expect-error [TS6133]
   private myNumber: string | undefined;
}

function getMyData(): string | undefined {
   return 'myData';
}

// Specify the message and a TS code for validation for `strict` mode
// @ts-expect-error [TS2532 - Object is possibly 'undefined']
getMyData().length;

// Other approach for ignoring a line:
getMyData().length; // @ts-expect-error [TS2532]

// Specify several TS code errors for validation for a line: 
// @ts-expect-error [TS2322, TS6133]
const object: { a: number } = { b: 5 };

// Specify several TS code errors with message description for validation
// @ts-expect-error [TS6133 - 'object' is declared but its value is never read, TS2322 - Type '{ b: number; }' is not assignable to type '{ a: number; }']
const sample: { a: number } = { b: 5 };

By default, the file extensions analyzed are tsx and ts.

Cli Options:

Option	Description
--tsConfigPath=<PATH>	Path to the tsconfig.json file to use. Defaults to the tsconfig.json in the current directory.
--restore	Since we have to change all @ts-expect-error to something else, this changes the content file. You can use this option to restore changed files.
--sourcePath=<PATH>	Path to the directory or the file containing @ts-expect-error to validate. You can specify several folders or files to make search more productive.
--outputFormat=<FORMAT>	The output format. Can be either json or human. Defaults to human.
--quiet	If present, suppresses all output except for report results.
--validationMode=<MODE>	Specifies the validation mode to use. Can be either default or strict. In default mode, only the expected error codes are validated. In strict mode, the error code and the first line of the error description are validated. Notice that strict mode is in alpha version. Default is default.

Example Usage:

//a package.json file
...
"scripts": {
  "ts-expect-error-validator": "ts-expect-error-validator --tsConfigPath=tsconfig.json --restore --sourcePath=src/myDir --sourcePath=src/someTsFile.ts --reportFormat=json --quiet"
}
...

//a cli comand
yarn ts-expect-error-validator

Hits

• There is no need to scan all project sources for pull requests, instead it's more useful to check only the changed files by running this command:

   yarn ts-expect-error-validator $(git diff --name-only HEAD | grep "\.ts$" | xargs -I {} echo "--sourcePath={}" | tr '\n' ' ')

• There is an ES Rule to ensure that code includes signatures for the validator.

License

This library is released under the MIT License.