Jasmine JavaScript测试 - toBe vs toEqual

问题描述

假设我有以下内容：

var myNumber = 5;
expect(myNumber).toBe(5);
expect(myNumber).toEqual(5);

上述两项测试都将通过。在评估数字时， toBe（）和 toEqual（）之间是否存在差异？如果是这样，当我应该使用一个而不是另一个？

Both of the above tests will pass. Is there a difference between toBe() and toEqual() when it comes to evaluating numbers? If so, when I should use one and not the other?

推荐答案

对于原始类型（例如数字，布尔值，字符串等） 。）， toBe 和 toEqual 之间没有区别;任何一个将适用于 5 ， true ，或蛋糕是谎言。

For primitive types (e.g. numbers, booleans, strings, etc.), there is no difference between toBe and toEqual; either one will work for 5, true, or "the cake is a lie".

了解 toBe 和 toEqual ，让我们想象三个对象。

To understand the difference between toBe and toEqual, let's imagine three objects.

var a = { bar: 'baz' },
    b = { foo: a },
    c = { foo: a };

使用严格比较（ === ），有些东西是相同的：

Using a strict comparison (===), some things are "the same":

> b.foo.bar === c.foo.bar
true

> b.foo.bar === a.bar
true

> c.foo === b.foo
true

但有些事情，即使他们是相等，不是相同，因为它们代表住在记忆中不同位置的对象。

But some things, even though they are "equal", are not "the same", since they represent objects that live in different locations in memory.

> b === c
false

Jasmine的 toBe matcher只不过是一个严格的相等比较的包装器

Jasmine's toBe matcher is nothing more than a wrapper for a strict equality comparison

expect(a.foo).toBe(b.foo)

与

expect(a.foo === b.foo).toBe(true)

不要只听我的话;请参阅。

Don't just take my word for it; see the source code for toBe.

但 b 和 c 表示功能相当的对象;它们看起来像

But b and c represent functionally equivalent objects; they both look like

{ foo: { bar: 'baz' } }

如果我们可以说 b 和，那会不会很好c 即使它们不代表同一个对象也是相等的？

Wouldn't it be great if we could say that b and c are "equal" even if they don't represent the same object?

输入 toEqual ，它检查深度相等（即通过对象进行递归搜索以确定其键的值是否相等）。以下两项测试都将通过：

Enter toEqual, which checks "deep equality" (i.e. does a recursive search through the objects to determine whether the values for their keys are equivalent). Both of the following tests will pass:

expect(b).not.toBe(c);
expect(b).toEqual(c);

希望这有助于澄清一些事情。

Hope that helps clarify some things.

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