带有用户输入的 Python 3 单元测试

Question

我对 Python 单元测试完全陌生。我需要将它用于我必须提交的项目。我有点知道从哪里开始，看起来我们基本上将测试参数放入我们在程序中定义的函数中，然后输入预期的结果。如果输出了预期的结果，就OK了，否则就失败了，或者报错。

所以我的问题是我有多个用户输入存储在 for 循环或 while 循环内的变量中。我什至不知道从哪里开始为他们设置测试值。

这是我所有的代码：

studentTripExpenses = {}

def dictCreate(studentAmount):
    for i in range(0, studentAmount):
        studentName = input("What is the name of the student? ")
        expenseList = []
        print("Enter 'done' to move to the next student.")
        while True:
            expense = input("What is the cost of this expense? ")
            if expense.lower() == 'done':
                break
            elif (float(expense) >= 0) or (float(expense) < 0):
                expenseList.append(float(expense))
            elif not expense.isdigit():
                print("Please enter a number or enter 'done' to move on.")
        studentTripExpenses[studentName] = expenseList
    return studentTripExpenses

def studentCost(dct):
    for i in dct:
        #Variable for individual costs of student
        personalCost = 0
        #Determines the total cost for each student
        for x in dct[i]:
            personalCost = personalCost + x
        #Sets each students value to their total cost to two decimal places
        dct[i] = float("%.2f" % personalCost)
    return dct

def amountsDue(expenseLst, studentAvgPrice):
        #Runs through the dictionary of students and individual total trip costs
        for key in expenseLst:
            maxPerson = max(expenseLst, key=expenseLst.get)
            costDifference = 0
            #Determines who owes who how much money
            if max(expenseLst.values()) > expenseLst[key]:
                costDifference = studentAvgPrice-expenseLst[key]
                if (costDifference < 0):
                    costDifference = costDifference * -1
                print("%s owes %s $%.2f" % (key, maxPerson, costDifference))

def main():
    numOfStudents = int(input("How many students are going on the trip? "))
    studentCostDict = dictCreate(numOfStudents)
    studentTripExpenses = studentCost(studentCostDict)

    totalCost = 0

    #Gets the total cost for all students
    for key in (studentTripExpenses):
        totalCost = totalCost + studentTripExpenses[key]

    #Changes the total cost to 2 decimal places
    totalCost = float("%.2f" % totalCost)

    #Determines the average amount spent per student
    avgCost = float("%.2f" % (totalCost/len(studentTripExpenses)))

    amountsDue(studentTripExpenses, avgCost)

main()

Answer 1

您可以使用 mocking，将函数或类替换为测试提供的版本。您可以使用unittest.mock() module 来执行此操作。

在这种情况下，您可以修补模块中的input() 名称；将调用模拟对象而不是内置函数：

from unittest import mock
from unittest import TestCase
import module_under_test

class DictCreateTests(TestCase):
    @mock.patch('module_under_test.input', create=True)
    def testdictCreateSimple(self, mocked_input):
        mocked_input.side_effect = ['Albert Einstein', '42.81', 'done']
        result = dictCreate(1)
        self.assertEqual(result, {'Albert Einstein': [42.81]})

因为input在你的模块中不存在（它是一个内置函数），我告诉mock.patch() decorator创建名称；现在这个input 将被使用而不是内置函数。

side_effect attribute 允许您声明多个结果；每次调用模拟时，它都会返回该列表中的 下一个值。所以第一次返回'Albert Einstein'，下一次返回'42.81'，以此类推

这让您可以模拟实际的用户输入。

如果您正确地进行了测试，您会注意到您的函数中存在错误；当输入除done 或有效数值以外的任何内容时，float() 调用将引发 ValueError 异常。您需要重新编写代码以解决此问题。尝试使用mocked_input.side_effect = ['Albert Einstein', 'Not an expense', '42.81', 'done'] 触发错误。