• 2026-09-09
• in Automation, Python, QA
• 3 min read

File Sorter (Part 2): Functions, Dry-Run, and Safe Duplicates

In my previous post, I built a basic Python script to clean up a cluttered Downloads folder. It did the job, but it was just a procedural script with clear risks: it could overwrite files with duplicate names, and running it meant making changes directly to the filesystem without a preview.

As someone training to become a QA engineer, I realized this was not reliable enough. Before writing automated tests, code must be modular and predictable.

Here is how I upgraded the script to make it safer and test-ready.

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What Changed?

1. Modular Functions (Preparing for Pytest)

In the first version, everything ran in a single loop. To test logic effectively, inputs and outputs need to be isolated. I split the logic into dedicated functions:

• classify_file(): pure logic that only determines the category.
• get_unique_path(): handles file naming collisions.
• move_file(): handles the actual filesystem operation.
• sort_directory(): coordinates the entire workflow.

2. Collision Handling: No Overwrites

If you download report.pdf multiple times, standard move operations might overwrite older files. I added get_unique_path() to append an incrementing index if a file already exists in the target folder:

def get_unique_path(destination: Path) -> Path:
    if not destination.exists():
        return destination
    counter = 1
    while True:
        new_filename = (
            f"{destination.stem}_{counter}{destination.suffix}"
        )
        new_destination = destination.parent / new_filename
        if not new_destination.exists():
            return new_destination
        counter += 1

Now, report.pdf safely becomes report_1.pdf, protecting user data.