type expect

@nick/is/type/expect

expectType

Signature

function expectType<T>(value: T): void;

A no-op function that is used for explicit type checking in TypeScript.

This function is a generic function that takes a single type parameter T and a single argument of type T. The function does not perform any operations at runtime, but it is used to check that the type of the argument passed to it is a match for type T. This is useful for testing purposes.

Parameters

Name	Info
value	THe value to assert the type of.

Returns

Nothing.

Category

Testing

Examples

import { expectType } from "@nick/is/type/expect";

let result: string | number = "hello world".toString();

// This will raise a type error if `result` is not a `string`
expectType<string>(result);

const literal = "hello world";

// This will raise a type error if `literal` is not a string literal
expectType<"hello world">(literal);

ExpectType

Signature

export type ExpectType<TExpected, TActual extends TExpected> = TActual;

Type-level equivalent to the expectType function.

This type alias accepts 2 type parameters: TExpected and TActual. If the type of TActual is not assignable to TExpected, it will raise a compiler error indicating as much. This is useful for testing purposes.

Type Parameters

• TExpected
• TActual extends TExpected

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Category

Types