feat: Add simple output to allow consitent machine readable output

[tonur]

Closes #525

This pull request introduces a new option for generating simplified list diffs and refactors the comparison logic for named lists to improve determinism and flexibility. It also adds a utility for comparing YAML nodes, and makes some targeted improvements to output formatting and CLI options.

Feature: Simple List Diff Option

• Added a new CLI flag --simple-list-diff (and corresponding field in reportConfig) to allow users to toggle between detailed per-entry diffs and a simple overview (added/removed) for named lists. The flag is wired through the CLI, configuration, and core comparison logic. [1] [2] [3] [4] [5] [6]

Output: Diff Formatting Enhancements

• Enhanced the diff syntax output to optionally show only changed lines for modifications when the appropriate flag is set, and improved output formatting for additions by using the correct indentation. [1] [2] [3] [4]

[tonur]

Waiting for #527 to be completed before this is implemented.

[tonur]

After #527 was completed, this would also be an immense help to me. This change will close #525
I have merged the upstream changes into this branch, and confirmed that it still works:

Would this be something you'd be willing to accept? @HeavyWombat

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.10%. Comparing base (6f6bdc4) to head (4446e02).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #531      +/-   ##
==========================================
+ Coverage   82.32%   84.10%   +1.77%     
==========================================
  Files          17       18       +1     
  Lines        1765     2019     +254     
==========================================
+ Hits         1453     1698     +245     
- Misses        236      248      +12     
+ Partials       76       73       -3     

Flag	Coverage Δ
unittests	84.10% <100.00%> (+1.77%)	⬆️

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[tonur]

Any chance you'd be accepting this @HeavyWombat? :D

[HeavyWombat]

Any chance you'd be accepting this @HeavyWombat? :D

Hi @tonur, I am coming back to some of the pending PRs of dyff. Some of the recent updates to the tool make it hard for me to follow, what we wanted to achieve here. With #525 being tackled, I am wondering: Could you try to explain to me again what you want to achieve with this second one? May your use case or some pseudo diff outputs to help me understand your case? Thanks in adance!

[tonur]

@HeavyWombat thanks for following up on this!
My need is for a tool to grab all modified entries of a list in a yaml file.

Take fx the files from assets/issues/issue-525/:

What I want is to specify a flag, which I have called "--simple-list-diff --changed-entries", and then make dyff only output the changed entries on that list. (Note that it should probably just be a singular flag called "--output pure-yaml" or stuff like that.)
So the above comparison would result in this output:

name: a-type-of-file
allowed:
- digest: "sha256:1111111111111111111111111111111111111111111111111111111111111111"
  image: name/container
  registry: ghcr.io
  tag: 1.2.4
  field:
  - test
- digest: "sha256:22222222222222222222222222222222222222222222222222222222222222222"
  image: yes/i-am-an-image
  registry: docker.io
  tag: 1.2.4-test_with.symbols
- digest: "sha256:4444444444444444444444444444444444444444444444444444444444444444"
  image: oh-look/another-flaky
  registry: quay.io
  tag: 3.1.2-test-with-dashes
- digest: "sha256:0000000000000000000000000000000000000000000000000000000000000000"
  image: you-would-not/guess
  registry: docker.io
  tag: 1.3.2
- digest: "sha256:6666666666666666666666666666666666666666666666666666666666666666"
  image: additional/image
  registry: new.io
  tag: 9.8.7

The important part is that the output is machine readable, so that I can use it for automation and run a CI/CD pipeline that handles only the modified entries.

Does that explain it?