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Level 4 / Project 05 - Path Safe File Mover

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Estimated time: 55 minutes

Focus

  • safe move plans and collision prevention

Why this project exists

This project gives you level-appropriate practice in a realistic operations context. Goal: run the baseline, alter behavior, break one assumption, recover safely, and explain the fix.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-4/05-path-safe-file-mover
# Create sample source files first:
mkdir -p data/source && echo "hello" > data/source/report.csv && echo "world" > data/source/data.txt
python project.py --source data/source --dest data/dest --output data/move_log.json
pytest -q

Expected terminal output

{
  "total_files": 2,
  "moved": 2,
  "failed": 0,
  "operations": [ ... ]
}
6 passed

Expected artifacts

  • data/dest/ — moved files
  • data/move_log.json — detailed move log with timestamps
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add a --pattern flag to only move files matching a glob (e.g., *.csv).
  2. Add a --backup flag that copies instead of moves, preserving the originals.
  3. Re-run script and tests — add a test for the glob filter.

Break it (required) — Core

  1. Try to move files from a non-existent source directory — observe the error.
  2. Create a situation where a move fails mid-batch (e.g., read-only destination) and verify rollback.
  3. Run the same move twice and confirm collision handling works.

Fix it (required) — Core

  1. Add a pre-check that validates source and destination directories before planning.
  2. Ensure the move log records both successes and rollbacks clearly.
  3. Re-run until all tests pass.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. Why does the mover use a two-phase approach (plan then execute) instead of moving immediately?
  2. How does resolve_collision avoid infinite loops — what guarantees it terminates?
  3. Why does _rollback iterate in reverse order?
  4. What are the risks of shutil.move across different filesystems?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

Stuck? Ask AI

If you are stuck after trying for 20 minutes, use one of these prompts:

  • "I am working on Path Safe File Mover. I got this error: [paste error]. Can you explain what this error means without giving me the fix?"
  • "I am trying to prevent file name collisions when moving files. Can you explain strategies for handling duplicate file names?"
  • "Can you explain the difference between shutil.move() and Path.rename() and when to use each?"
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