(CAT-2484) Prevent YAML corruption by making PuppetLint instances file-type aware

[gavindidrichsen]

Context

GitHub Issue #254 revealed that puppet-lint's --fix flag was incorrectly overwriting YAML files with Puppet manifest content.

The root cause was in the file processing logic in bin.rb, which was applying fix logic to all discovered files (*.pp, *.yaml, *.yml) regardless of file type. This resulted in YAML configuration files being corrupted with Puppet manifest content, creating potential data loss scenarios in production environments.

Changes

Since each file has an associated PuppetLint instance, then I refactored the file-write logic from bin.rb into the PuppetLint. This refactor makes each PuppetLint file instance aware of its file type and fix eligibility. Each PuppetLint instance is now responsible for its own behavior based on its file type (and other constraints)

Now bin.rb simply calls fix() on each PuppetLint instance if the user passes the --fix flag. Only if the instance is elegible for a fix will this occur.

Testing

• manually tested the fix with bundle exec puppet-lint --fix spec/fixtures/test/manifests/issue_254_overwriting_yaml/
• added rspec automated tests as well.

[gavindidrichsen]

My first commit is a test that verifies the issue, e.g.,

➜  puppet-lint git:(b25f35d) ✗ bundle exec rspec
...
...
  when fixing a directory containing both .pp and .yaml files
    does not overwrite YAML files (FAILED - 1)
    exitstatus

Failures:

  1) PuppetLint::Bin when fixing a directory containing both .pp and .yaml files does not overwrite YAML files
     Failure/Error: expect(yaml_after).to eq(original_yaml)
       
       expected: "---\nclasses:\n  foo-bar:\n    parameters: []\n    resources:\n      notify:\n        - title: hello\n"
            got: "class foo-bar {\n  notify { 'hello': }\n}\n"
       
       (compared using ==)
       
       Diff:
       @@ -1,7 +1,3 @@
       ----
       -classes:
       -  foo-bar:
       -    parameters: []
       -    resources:
       -      notify:
       -        - title: hello
       +class foo-bar {
       +  notify { 'hello': }
       +}
       
       
     # ./spec/unit/puppet-lint/bin_spec.rb:630:in `block (3 levels) in <top (required)>'

Finished in 2.89 seconds (files took 3.62 seconds to load)
125 examples, 1 failure

After applying the 2nd commit fix, then the tests pass green.