🐛 Fix metadata assert failure in clusterclass rollout test

[zhanggbj]

What this PR does / why we need it:
Add union() to convert a potential nil map to an empty map, otherwise the test will faile due to compare a nil map and an empty one.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #10839

/area testing

[fabriziopandini]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: ad1b18411a967488c77f5ab59e70edb0873b49b1

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabriziopandini

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 [fabriziopandini]

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

[sbueringer]

What is the pattern behind adding this to in some places but not in others?

[zhanggbj]

Hey @sbueringer , I only added union() for the cases which are more possible to compare a nil and empty map, when only have union() in one of Expect or BeEquivalentTo as below

		g.Expect(machineDeployment.Spec.Template.Annotations).To(BeEquivalentTo(
			union(
				mdTopology.Metadata.Annotations,
				mdClass.Template.Metadata.Annotations,
			),
		))

I think other cases are less likely to run into this situation, such as

		g.Expect(infrastructureMachineTemplate.GetAnnotations()).To(BeEquivalentTo(
			union(
				map[string]string{
					clusterv1.TemplateClonedFromGroupKindAnnotation: groupKind(mdClass.Template.Infrastructure.Ref),
					clusterv1.TemplateClonedFromNameAnnotation:      mdClass.Template.Infrastructure.Ref.Name,
				},
				ccInfrastructureMachineTemplate.GetAnnotations(),   ===> We defined expected annotations, and  if infrastructureMachineTemplate.GetAnnotations() are nil or empty, that's a failure we should catch.
			),
		))
		// MachineDeployment InfrastructureMachineTemplate.spec.template.metadata
		g.Expect(infrastructureMachineTemplateTemplateMetadata.Labels).To(BeEquivalentTo(
			ccInfrastructureMachineTemplateTemplateMetadata.Labels,  ===> Usually they either have labels defined or are nil
		))

[sbueringer]

Hm. I think the following might be a better option.

func expectMapsToBeEquivalent(g Gomega, m1, m2 map[string]string) {
	if m1 == nil {
		m1 = map[string]string{}
	}
	if m2 == nil {
		m2 = map[string]string{}
	}
	g.ExpectWithOffset(1, m1).To(BeEquivalentTo(m2))
}

This would then be used like this (everywhere)

expectMapsToBeEquivalent(g, clusterObjects.InfrastructureCluster.GetLabels(),
		union(
			map[string]string{
				clusterv1.ClusterNameLabel:          cluster.Name,
				clusterv1.ClusterTopologyOwnedLabel: "",
			},
			ccInfrastructureClusterTemplateTemplateMetadata.Labels,
		),
	)

(It's not important/urgent, I can also take it over if you want, up to you)

[zhanggbj]

Look great, feel free to take it over :-)

[sbueringer]

Opened a PR: #10851