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assert_equals.ts
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assert_equals.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
import { equal } from "./equal.ts";
import { buildMessage, diff, diffstr, format } from "../internal/mod.ts";
import { AssertionError } from "./assertion_error.ts";
import { red } from "../fmt/colors.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);
}