deno.land / std@0.224.0 / assert / assert_almost_equals.ts

assert_almost_equals.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.import { AssertionError } from "./assertion_error.ts";
/** * Make an assertion that `actual` and `expected` are almost equal numbers * through a given tolerance. It can be used to take into account IEEE-754 * double-precision floating-point representation limitations. If the values * are not almost equal then throw. * * @example * ```ts * import { assertAlmostEquals } from "https://deno.land/std@$STD_VERSION/assert/mod.ts"; * * assertAlmostEquals(0.01, 0.02, 0.1); // Doesn't throw * assertAlmostEquals(0.01, 0.02); // Throws * assertAlmostEquals(0.1 + 0.2, 0.3, 1e-16); // Doesn't throw * assertAlmostEquals(0.1 + 0.2, 0.3, 1e-17); // Throws * ``` */export function assertAlmostEquals( actual: number, expected: number, tolerance = 1e-7, msg?: string,) { if (Object.is(actual, expected)) { return; } const delta = Math.abs(expected - actual); if (delta <= tolerance) { return; }
const msgSuffix = msg ? `: ${msg}` : "."; const f = (n: number) => Number.isInteger(n) ? n : n.toExponential(); throw new AssertionError( `Expected actual: "${f(actual)}" to be close to "${f(expected)}": \delta "${f(delta)}" is greater than "${f(tolerance)}"${msgSuffix}`, );}
std

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6 months ago