编写描述性单元测试 [英] Write descriptive unit tests

问题描述

我正在尝试用Python编写单元测试，并且很难找到一种描述性的方法来做事。我有一个JavaScript背景，我使用 mocha 这有助于我描述。

I'm trying to write unit tests in Python and struggle to find a descriptive way to do things. I have a JavaScript background and I use mocha which helps me be descriptive.

这就是我所说的描述性：

This is what I mean by "descriptive":

foo.js

exports.foo = function (type, isLogged, iOk) {
    if (type === undefined) throw new Error('a cannot be undefined');
    if (isLogged === undefined) throw new Error('b cannot be undefined');
    if (isLogged) {
        if (type === 'WRITER') {
            return isOk ? "writer" : -1;
        } else {
            return "something else"
        }
    }
}

foo.spec.js

describe('#foo()', function () {
    context('when type is undefined', function () {
      ...
    })
    context('when isLogged is undefined', function () {
      ...
    })
    context('when type is defined', function () {
        context('when isLogger is not defined', function () {
         ...
        })
        context('when isLogged is defined', function () {
            context('when type is not WRITER', function () {
             ...
            })
            context('when type is WRITER', function () {
                context('when isOk is true', function () {
                 ...
                })
            })
        }) 
    })
})

当我用Python编写单元测试时，我最终会得到这样的结果：

While when I write unit tests in Python, I end up with somthing like this:

foo.spec.py

class TestFoo:
    def test_when_type_is_undefined(self):
        ...
    def test_when_isLogged_is_undefined(self):
        ...
    # This test name is too long
    def test_when_type_is_defined_and_isLogged_is_undefined_and_type_is_writer_when_is_ok_is_true(self):
        ...

如何以更好的方式构建这些测试？有关描述性单元测试的最佳实践是什么？是否有好的单元测试的好例子？

How to structure these test in a better way? What are the best practices regarding descriptive unit testing? Are there good examples of good unit tests?

推荐答案

你可以使用 pyspecs 在你的代码中有更多类似BDD的语法。

You can use pyspecs to have a more BDD-like syntax in your code.

from pyspecs import given, when, then, and_, the, this

with given.two_operands:
    a = 2
    b = 3

    with when.supplied_to_the_add_function:
        total = a + b

        with then.the_total_should_be_mathmatically_correct:
            the(total).should.equal(5)

        with and_.the_total_should_be_greater_than_either_operand:
            the(total).should.be_greater_than(a)
            the(total).should.be_greater_than(b)

    with when.supplied_to_the_subtract_function:
        difference = b - a

        with then.the_difference_should_be_mathmatically_correct:
            the(difference).should.equal(1)

输出

Output

# run_pyspecs.py

  | • given two operands 
  |   • when supplied to the add function 
  |     • then the total should be mathmatically correct 
  |     • and the total should be greater than either operand 
  |   • when supplied to the subtract function 
  |     • then the difference should be mathmatically correct 

(ok) 6 passed (6 steps, 1 scenarios in 0.0002 seconds)

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