使用 Openpyxl 在 Python 中模拟 Excel 文件内容

Question

下面是一个更复杂的问题的简化，这里我需要验证 Excel 文件的内容。我想为我需要的功能编写单元测试，但理想情况下我想模拟这些测试，这样我就不必有可用的示例 Excel 表。

以下功能起作用：

functions_to_test.py：

import openpyxl

def read_excel_file_contents(filename: str, sheetname: str, cell: str) -> str:
    wb = openpyxl.load_workbook(filename, read_only=True)
    ws = wb[sheetname]
    return ws[cell].value

test.py

import unittest
from unittest.mock import MagicMock, patch

import functions_to_test


class FunctionsToTest(unittest.TestCase):
    
    @patch('functions_to_test.openpyxl')
    def test_read_mocked_excel_file(self, openpyxl_mock):
        wb = openpyxl_mock.workbook()
        ws = openpyxl_mock.worksheet()

        openpyxl_mock.load_workbook = MagicMock(return_value=wb)
        wb.get_sheet_by_name = MagicMock(return_value=ws)
        ws["A1"].value = "Some content"       
        self.assertEqual(
            functions_to_test.read_excel_file_contents("a mocked excel file", sheetname="somesheet", cell="A1"), 
            "Some content"
            )


if __name__ == "__main__":
    unittest.main()

输出：

======================================================================
FAIL: test_read_mocked_excel_file (__main__.FunctionsToTest)
Assert the correct contents of reading a mocked Excel file
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\markh\AppData\Local\Programs\Python\Python39\lib\unittest\mock.py", line 1337, in patched
    return func(*newargs, **newkeywargs)
  File "c:\Users\markh\Python\Testing\test.py", line 18, in test_read_mocked_excel_file
    self.assertEqual(
AssertionError: <MagicMock name='openpyxl.workbook().__ge[45 chars]200'> != 'Some content'

----------------------------------------------------------------------
Ran 1 test in 0.003s

我相信我必须为此使用 MagicMock()，但似乎无法弄清楚到底如何。 我看过Mocking Method Calls In Python，但与那里给出的答案相比，我的情况似乎更进一步。

Answer 1

考虑对test.py 进行以下修改（请检查一切是否合理）：

基本上，我的想法是确保新初始化的工作簿wb 有一个使用.create_sheet 标记为somesheet 的工作表。然后，将ws 设置为该工作表，最后设置单元格A1 的值。

test.py

import unittest
from unittest.mock import MagicMock, patch

import functions_to_test


class FunctionsToTest(unittest.TestCase):

    @patch('functions_to_test.openpyxl')
    def test_read_mocked_excel_file(self, openpyxl_mock):
        wb = openpyxl_mock.workbook()
        wb.create_sheet("somesheet")
        ws = wb["somesheet"]
        ws["A1"].value = "Some content"

        openpyxl_mock.load_workbook = MagicMock(return_value=wb)
        self.assertEqual(
            functions_to_test.read_excel_file_contents(
                "a mocked excel file",
                sheetname="somesheet",
                cell="A1"
            ),
            "Some content"
        )


if __name__ == "__main__":
    unittest.main()