飞镖测试大致相等 [英] Dart test with roughly equal

问题描述

我现在正在尝试使用 dart:test 功能.

I am now trying to use dart:test features.

我可以这样写:

expect(areaUnderCurveWithRectangleRule(f1, 0,1,1000), equals(2));

但正如我们所知，在浮点/双精度计算中，没有精确相等这样的东西.所以我想知道是否有一种大致相同的测试方法?如果它们的差异在某个 epsilon(例如 1E-6)或某个百分比内，它将为两个双精度值返回 true?

But as we know, in float/double calculation, there is no such thing as precise equal. So I am wondering if there is a roughly equal testing method? It will return true for two double values, if their difference is within a certain epsilon (say, 1E-6) or certain percentage?

如果没有，这会向 Dart 团队提出一个很好的功能请求吗?

If not, will this make a good feature request to Dart team?

推荐答案

dart:test 提供了一个 closeTo 用于此目的的匹配器:

dart:test provides a closeTo matcher for this purpose:

expect(areaUnderCurveWithRectangleRule(f1, 0,1,1000), closeTo(2, epsilon));

请注意，closeTo 使用绝对增量，这可能不适合具有非常不同幅度的浮点值.

Note that closeTo uses an absolute delta, which might not be appropriate for floating-point values that have very different magnitudes.

如果你想要一个基于百分比比较的版本，应该很容易用你自己的函数包装 closeTo，例如:

If you instead want a version that compares based on a percentage, it should be easy to wrap closeTo with your own function, e.g.:

Matcher closeToPercentage(num value, double fraction) {
  final delta = value * fraction;
  return closeTo(value, delta);
}

这篇关于飞镖测试大致相等的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！