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std/assert/assert_throws.ts

Deno standard library
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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.import { assertIsError } from "./assert_is_error.ts";import { AssertionError } from "./assertion_error.ts";
/** * Executes a function, expecting it to throw. If it does not, then it * throws. * * @example * ```ts * import { assertThrows } from "https://deno.land/std@$STD_VERSION/assert/assert_throws.ts"; * * Deno.test("doesThrow", function (): void { * assertThrows((): void => { * throw new TypeError("hello world!"); * }); * }); * * // This test will not pass. * Deno.test("fails", function (): void { * assertThrows((): void => { * console.log("Hello world"); * }); * }); * ``` */export function assertThrows( fn: () => unknown, msg?: string,): unknown;/** * Executes a function, expecting it to throw. If it does not, then it * throws. An error class and a string that should be included in the * error message can also be asserted. * * @example * ```ts * import { assertThrows } from "https://deno.land/std@$STD_VERSION/assert/assert_throws.ts"; * * Deno.test("doesThrow", function (): void { * assertThrows((): void => { * throw new TypeError("hello world!"); * }, TypeError); * assertThrows( * (): void => { * throw new TypeError("hello world!"); * }, * TypeError, * "hello", * ); * }); * * // This test will not pass. * Deno.test("fails", function (): void { * assertThrows((): void => { * console.log("Hello world"); * }); * }); * ``` */export function assertThrows<E extends Error = Error>( fn: () => unknown, // deno-lint-ignore no-explicit-any ErrorClass: new (...args: any[]) => E, msgIncludes?: string, msg?: string,): E;export function assertThrows<E extends Error = Error>( fn: () => unknown, errorClassOrMsg?: // deno-lint-ignore no-explicit-any | (new (...args: any[]) => E) | string, msgIncludesOrMsg?: string, msg?: string,): E | Error | unknown { // deno-lint-ignore no-explicit-any let ErrorClass: (new (...args: any[]) => E) | undefined = undefined; let msgIncludes: string | undefined = undefined; let err;
if (typeof errorClassOrMsg !== "string") { if ( errorClassOrMsg === undefined || errorClassOrMsg.prototype instanceof Error || errorClassOrMsg.prototype === Error.prototype ) { // deno-lint-ignore no-explicit-any ErrorClass = errorClassOrMsg as new (...args: any[]) => E; msgIncludes = msgIncludesOrMsg; } else { msg = msgIncludesOrMsg; } } else { msg = errorClassOrMsg; } let doesThrow = false; const msgSuffix = msg ? `: ${msg}` : "."; try { fn(); } catch (error) { if (ErrorClass) { if (error instanceof Error === false) { throw new AssertionError(`A non-Error object was thrown${msgSuffix}`); } assertIsError( error, ErrorClass, msgIncludes, msg, ); } err = error; doesThrow = true; } if (!doesThrow) { msg = `Expected function to throw${msgSuffix}`; throw new AssertionError(msg); } return err;}