fix: Allow patches with empty files with multiple newlines or comments

[jchanam]

Fixes https://github.com/kubernetes-sigs/kustomize/issues/5487

Right now, when a file is empty, the patches given by the resmap (sm patches) or the jsonpatch is nil. When the file has only comments in it (virtually empty if we think about changes to be made) or multiple newlines, the result given by said functions is an empty slice.

I've changed the check for when we can't allow to have a patch that is valid for both SM and JSON, so it allows empty changes (both nil or empty slices).

Extra comments:

• I think that it'd be better to change the functions and return a nil object, instead of an empty slice, but I'm unsure on where to do those changes.
• Also, I can't make the tests to run locally as they complain for the content file to be empty, and that should not be the case as it's perfectly ok for the built binary to use empty patches.

I'll be more than happy to work on these two with some help or guidance.

[k8s-ci-robot]

This PR has multiple commits, and the default merge method is: merge. You can request commits to be squashed using the label: tide/merge-method-squash

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[k8s-ci-robot]

Welcome @jchanam!

It looks like this is your first PR to kubernetes-sigs/kustomize 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes-sigs/kustomize has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. :smiley:

[k8s-ci-robot]

Hi @jchanam. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[jchanam]

Hi @stormqueen1990 @varshaprasad96,

Could I get some help in getting this approved?

Thank you!

[stormqueen1990]

Hi @stormqueen1990 @varshaprasad96,

Could I get some help in getting this approved?

Thank you!

Hi there, @jchanam!

I am taking a look at this and got a bit confused with the comment you made in the PR description about the tests. Do you mean that tests are currently failing locally?

[stormqueen1990]

/test all

[jchanam]

Hi @stormqueen1990 ,

Yes, I meant that. It looks like there are a test checking if the input is not empty, but the goal of my code is testing specifically that, as it should not fail. If we add a file to kustomize that is empty, it should simply not produce any output, instead of failing.

Also, now the tests here say that there's a diff found on the file I've modified. How can I fix that or change extra code so the tests continue?

Thank you!

[stormqueen1990]

/test all

[jchanam]

@stormqueen1990 Sorry for the late response. I think I was able to follow your guidance and fix the tests.

[jchanam]

/retest

[k8s-ci-robot]

@jchanam: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[stormqueen1990]

@stormqueen1990 Sorry for the late response. I think I was able to follow your guidance and fix the tests.

Hi there, @jchanam! Thanks for updating this!

[stormqueen1990]

/retest

[jchanam]

@stormqueen1990 looks like the tests were not run. Could you please force them in any way? thank you!

[jchanam]

@stormqueen1990 Could you please help me with the linter errors?

Error: plugin/builtin/patchtransformer/PatchTransformer_test.go:1128:29: test helper function should start from t.Helper() (thelper)
`, someDeploymentResources, func(t *testing.T, err error) {
                            ^
Error: plugin/builtin/patchtransformer/PatchTransformer_test.go:1154:29: test helper function should start from t.Helper() (thelper)
`, someDeploymentResources, func(t *testing.T, err error) {

I don't understand why it's complaining when I've followed the same structure as for other tests

[stormqueen1990]

@stormqueen1990 Could you please help me with the linter errors?

Error: plugin/builtin/patchtransformer/PatchTransformer_test.go:1128:29: test helper function should start from t.Helper() (thelper)
`, someDeploymentResources, func(t *testing.T, err error) {
                            ^
Error: plugin/builtin/patchtransformer/PatchTransformer_test.go:1154:29: test helper function should start from t.Helper() (thelper)
`, someDeploymentResources, func(t *testing.T, err error) {

I don't understand why it's complaining when I've followed the same structure as for other tests

Hi @jchanam, our linter requires test helper functions to have an invocation to t.Helper() at the beginning. You just need to add that statement as the first statement in the helper function. This is standard Go, you can read more about it here: https://pkg.go.dev/testing#T.Helper. I apologize for not seeing (and flagging) it earlier.

As for the tests, /test all and /retest will only trigger the Prow presubmit tests. You can check the logs for those tests by clicking the details in the kustomize-presubmit-master check in your pull request status.

[jchanam]

@stormqueen1990 Thank you so much for the explanation! I've just added them and pushed the changes.

[jchanam]

@stormqueen1990 what is the following step now that the PR passed all the tests? Could this PR be merged?

[stormqueen1990]

@stormqueen1990 what is the following step now that the PR passed all the tests? Could this PR be merged?

Hi there, @jchanam! The next step is the review and then approval by a maintainer (I am just a reviewer). Once one of the maintainers approve this pull request using /approve it will be merged automatically by Prow. You can read more about the pull request process in Kubernetes projects in the Contributor Documentation: https://www.kubernetes.dev/docs/guide/pull-requests/

[jchanam]

Hi!

I'm still waiting for any maintainer to approve and merge this. Is there any way to ping anyone so they can check this?

[stormqueen1990]

Hi!

I'm still waiting for any maintainer to approve and merge this. Is there any way to ping anyone so they can check this?

@koba1t or @varshaprasad96: could you please take a look at this PR when you get a chance?

[stormqueen1990]

/ok-to-test

[koba1t]

/assign

[jchanam]

Hi! Could we have this PR merged please?

[koba1t]

Thanks @jchanam

/lgtm /approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jchanam, koba1t

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [koba1t]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment