assertType

import { assertType } from "jsr:@ende/testing/types";

function

function assertType<T extends boolean>(expectTrue: T): void

Asserts at compile time that the provided type argument's type resolves to the expected boolean literal type.

expectTrue: T: True if the passed in type argument resolved to true.

Example: Usage

import { assertType, IsExact, IsNullable } from "@ende/testing/types";

const result = "some result" as string | number;

// compile error if the type of `result` is not exactly `string | number`
assertType<IsExact<typeof result, string | number>>(true);

// causes a compile error that `true` is not assignable to `false`
assertType<IsNullable<string>>(true); // error: string is not nullable

Source