pdf-approval 0.1.1

Lightweight PDF approval testing library.

pdf-approval

A lightweight Python library for approval (snapshot) testing of PDF outputs by comparing raw bytes.

Features

• Binary Compare: Verifies exact byte-for-byte match between newly generated PDFs and their approved versions.
• Easy Baseline Management: Stores .approved.pdf in source control, creates a .received.pdf on mismatch.
• Auto-Approve: Allows updating baselines automatically if desired.
• Cross-Platform: Works on Windows, macOS, and Linux.
• Test Runner Agnostic: Raises AssertionError on mismatch (works with Pytest, Unittest, or any runner).

Installation

pip install pdf-approval

Quick Start

1. Generate or obtain your PDF in bytes (e.g., from a report generator).
2. Call verify_pdf(pdf_bytes, "my_report"). This looks for my_report.approved.pdf and compares it to the new PDF bytes.
3. If no .approved.pdf is found or they differ, the library writes a .received.pdf file and raises an error:
   • Inspect the new PDF to ensure it’s correct.
   • Approve by renaming it or calling approve_received("my_report").

Example

from pdf_approval.approval_util import verify_pdf, approve_received

def test_generate_monthly_report():
    # Suppose we create some PDF data
    pdf_data = create_monthly_report()  # returns raw PDF bytes
    
    # Compare to an approved file named 'monthly_report.approved.pdf'
    verify_pdf(pdf_data, "monthly_report")

    # If mismatch => test fails, a 'monthly_report.received.pdf' is produced.
    # If it doesn't exist => also fails, instructing you to approve.
    # To approve changes (after checking them):
    # approve_received("monthly_report")

Auto-Approve

If you want the library to automatically update the .approved.pdf file when a mismatch is detected (bypassing the test failure), set an environment variable or use the library function:

export APPROVAL_AUTO_APPROVE=1 pytest

Or in code:

from pdf_approval.approval_util import set_auto_approve
set_auto_approve(True)

Use with caution – always inspect changes to ensure they’re valid.

Best Practices

1. Commit Approved Files: Check *.approved.pdf into version control.
2. Ignore Received Files: Add *.received.pdf to your .gitignore.
3. Review Mismatches: Don’t just blindly approve – open a diff or PDF viewer to confirm changes are valid.
4. Stable PDF Generation: Remove timestamps, IDs, or other variable data from your PDF if possible to avoid spurious diffs.
5. Auto-Approve in CI? Usually not recommended; you want test failures for unexpected changes.

Contributing

1. Fork or clone this repository.
2. Make changes in a dedicated branch.
3. Add or update tests as needed.
4. Submit a pull request.

All contributions, big or small, are welcome!

License

MIT License