Congratulations! You learned how to avoid potential issues related to testing applications that read files from disk. By using the methods covered in the course you can get more consistent results from your tests.

In this Code Conversation you learned how to:

Use io.StringIO to simulate a text file on disk
Perform file operations on a io.StringIO object
Decide when to use io.StringIO and when to avoid it
Understand possible alternatives
Mock a file object using unittest.mock

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Sample Code (.zip)

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Course Slides (.pdf)

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Congratulations, you made it to the end of the course! What’s your #1 takeaway or favorite thing you learned? How are you going to put your newfound skills to use? Leave a comment in the discussion section and let us know.

00:00 With this, you’ve made it to the end of this code conversation. And in this course, you learned how to use io.StringIO to simulate a text file on disk.

00:09 You learned how to perform file operations on a io.StringIO object and saw that it works the same as an io.TextIOWrapper object, which is the one that you get when using the open() function.

00:20 You also learned how you could decide when to use io.StringIO for your tests, for example, and when you should avoid it. You got to understand some possible alternatives and when you get the slides, there’s also links in there and I’ll share some more coming up.

00:34 And finally, you also saw an alternative of using io.StringIO, and that was how to mock a file object using unittest.mock.

00:44 Alright, so here’s a couple of additional resources for you. If you want to learn more about working with files in Python, then you can check out the article shown on top that has a tutorial and also a video course and it also handles topics such as using the tempfile module.

01:00 Then there’s the tutorial and course on understanding the Python mock object library, where you’ll dive deeper into using unittest.mock for mocking objects.

01:10 And finally, I have also a resource for you for using Python’s mmap module where you can do improved file input/output using memory mapping. And again, this exists as a tutorial and a video course.

01:24 Alright, that’s all for today. Thanks for joining me in this code conversation on simulating a text file in Python. Hope you’ll have a nice day and see you around Real Python.

SwingPy on Aug. 3, 2024

Would’ve been good to have some benchmarking showing how StringIO is faster than reading the file. Also, I understand that the functions are both simple enough, but I think a bit of a refactoring was in order as upcase_file_content_from_path has “duplicated code” from upcase_file_content

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Simulate a Text File in Python (Summary)