python unittest assertCountEqual 使用“is"而不是“=="? [英] python unittest assertCountEqual uses 'is' instead of '=='?

问题描述

我正在尝试使用 python 的 unittest 库来编写一些单元测试.我有一个函数返回一个无序列表的对象.我想验证对象是否相同，并且我正在尝试使用 assertCountEqual 来做到这一点.

然而，尽管各个对象彼此相等 (==)，但这似乎失败了.这是断言失败的差异"输出:

First has 1, Second has 0: Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector),5000.向量(0.00, 0.00)), ent=None, oth=None, invalid=False)第一个有 1，第二个有 0: Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector, Vector, 0.000)0.00)), ent=None, oth=None, invalid=False)第一个有 0，第二个有 1: Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.000),(500.00), 0 Vector), ent=None, oth=None, invalid=False)第一个有 0，第二个有 1: Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector, Vector(500.000).000)0.00)), ent=None, oth=None, invalid=False)

验证它们是否相等:

<预><代码>>>>i = Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), N), Vector(0.00), Vector(0.00),其他=无，无效=假)>>>j = Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), N), Vector(0.00), Vector(0.00),其他=无，无效=假)>>>我==j真的>>>i = Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00), 0.0.0), Vector无，其他=无，无效=假)>>>j = Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00), 0.0.0), Vector无，其他=无，无效=假)>>>我==j真的

我的猜测是 assertCountEqual 函数正在检查两者是否具有相同的身份(例如 i is j)，而不是相等.

• 是否有提供相同差异的单元测试功能能力，但使用相等比较而不是身份?
• 或者，有什么方法可以编写一个函数来执行类似于 assertCountEqual?

编辑:我正在运行 python 3.2.2.

解决方案

你可以自己找比较是如何完成的:

• 从每个可迭代对象生成一个列表
• 使用 collections.Counter 来计算对象 - 有效仅适用于可散列元素
• 如果元素不可散列，比较它们直接

因为您的 Intersection 是对象，所以它们是 hashable 每个 default，但如果你不提供合适的哈希函数(如果你提供比较方法，你应该这样做) 他们将被视为不同.

那么，你的 Intersection 类是否满足了哈希合约?

I am trying to use python's unittest library to write some unit tests. I have a function that returns an unordered list of objects. I want to verify that the objects are the same, and I am trying to use assertCountEqual to do this.

However, this seems to be failing, despite the individual objects being equal (==) to each other. Here is the 'diff' output from the assertion failure:

First has 1, Second has 0:  Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
First has 1, Second has 0:  Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
First has 0, Second has 1:  Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
First has 0, Second has 1:  Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)

Verifying that they are equal:

>>> i = Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
>>> j = Intersection(time=8.033252939677466e-08, del_time=8.033252939677466e-08, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
>>> i == j
True
>>> i = Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
>>> j = Intersection(time=-9.918729244820295e-16, del_time=-9.918729244820295e-16, pos=Vector(10.00, 0.00), line=Line(Vector(500.00, 0.00), Vector(0.00, 0.00)), ent=None, oth=None, invalid=False)
>>> i == j
True

My guess is that the assertCountEqual function is checking if the two have the same identity (e.g. i is j), rather than equality.

• Is there a unittest function that will provide the same diff capabilities, but use equality comparison, rather than identity?
• Alternatively, is there some way I can write a function that performs similarly to assertCountEqual?

EDIT: I am running python 3.2.2.

解决方案

you can look for yourself how the comparison is done:

• generate a list from each iterable
• use a collections.Counter to count the objects - works only for hashable elements
• if the elements are not hashable, compare them directly

as your Intersections are objects, they are hashable per default, but if you don't provide a suitable hash function (which you should do if you provide comparison methods) they will be considered different.

so, does your Intersection class fullfill the hash contract?

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