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std/assert/assert_equals.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.import { equal } from "./equal.ts";import { format } from "./_format.ts";import { AssertionError } from "./assertion_error.ts";import { red } from "../fmt/colors.ts";import { buildMessage, diff, diffstr } from "./_diff.ts";import { CAN_NOT_DISPLAY } from "./_constants.ts";
/** * Make an assertion that `actual` and `expected` are equal, deeply. If not * deeply equal, then throw. * * Type parameter can be specified to ensure values under comparison have the * same type. * * @example * ```ts * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * assertEquals("world", "world"); // Doesn't throw * assertEquals("hello", "world"); // Throws * ``` * * Note: formatter option is experimental and may be removed in the future. */export function assertEquals<T>( actual: T, expected: T, msg?: string, options: { formatter?: (value: unknown) => string } = {},) { if (equal(actual, expected)) { return; } const { formatter = format } = options; const msgSuffix = msg ? `: ${msg}` : "."; let message = `Values are not equal${msgSuffix}`;
const actualString = formatter(actual); const expectedString = formatter(expected); try { const stringDiff = (typeof actual === "string") && (typeof expected === "string"); const diffResult = stringDiff ? diffstr(actual as string, expected as string) : diff(actualString.split("\n"), expectedString.split("\n")); const diffMsg = buildMessage(diffResult, { stringDiff }).join("\n"); message = `${message}\n${diffMsg}`; } catch { message = `${message}\n${red(CAN_NOT_DISPLAY)} + \n\n`; } throw new AssertionError(message);}