Template Test Files

Generate type tests using a data table.

This feature is available since TSTyche 4.0.

Usage

To mark a test file as a template, add the // @tstyche template comment directive at the top. When the directive is found, the default export of a file is interpreted as a type test text.

For example, the following:


// @tstyche template -- For documentation, see: https://tstyche.org/guides/template-test-files
 
let  = `import { expect, test } from "tstyche";
`;
 
for (const  of ["string", "number"]) {
   += `test("is ${} a string?", () => {
  expect<${}>().type.toBe<string>();
});
`;
}
 
export default ;

is interpreted as:


import { ,  } from "tstyche";
("is string a string?", () => {
  <string>()..<string>();
});
("is number a string?", () => {
  <number>()..<string>();
});

This feature requires Node.js 22.6 or later.

The type test text is loaded using the import() expression and replaced programmatically keeping the same file name. Therefore, this must be a TypeScript file and it must be executed at the same time. Fortunately, running TypeScript code with Node.js is now possible .