Simulate a Text File in Python (Overview)
Testing applications that read files from a disk can be challenging. Issues such as machine dependencies, special access requirements, and slow performance often arise when you need to read text from a file.
In this Code Conversation with instructor Martin Breuss, you’ll discover how to simplify this process by simulating text files with StringIO from the io module in Python’s standard library.
In this video course, you’ll learn how to:
- Use
io.StringIOto simulate a text file on disk - Perform file operations on a
io.StringIOobject - Decide when to use
io.StringIOand when to avoid it - Understand possible alternatives
- Mock a file object using
unittest.mock
Understanding how to simulate text file objects and mocking file objects can help to streamline your testing strategy and your development process.
00:00 Welcome to this code conversation about simulating a text file in Python. Imagine the following scenario. You’re developing an application that’ll read information from files on disk, not the most uncommon scenario.
00:14 You, of course, also want to write tests to make sure that everything works as expected. However, when writing these tests, you run into some issues. Reading a file from disk is inherently slow.
00:26 The file system can look quite differenty on different machines, and you may not even have access to create files in a standard location on disk when your tests run on different machines.
00:37
In this code conversation, I’ll walk you through using Python’s StringIO class from the standard library io module. StringIO is an in-memory file-like object that it can use to simulate a text file on disk.
00:50 In certain cases, it can be a good solution to reduce time spent on input/output operations, and for writing tests for file interactions that can reliably run in any environment.
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