Function assertType

assertType<T>(expectTrue): void

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

Type Parameters

T extends boolean
The expected type (true or false)

Parameters

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

Returns void

Example: Usage

import { assertType, IsExact, IsNullable } from "@std/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