Retry object updates on conflict in receiver tests

[jojinkb]

Fixes #473

Problem

Several receiver test steps mutate an object immediately after an Eventually block that keys off a condition. The reconciler's deferred patch (patch.SerialPatcher) commits its changes with multiple sequential API requests: the conditions patch first, then metadata/spec, then the remaining status fields (observedGeneration, lastHandledReconcileAt, webhookPath). The Eventually can therefore return as soon as the conditions patch lands, while the trailing status patch is still in flight. If that patch commits between the test's Get and Update, the Update fails with an optimistic concurrency conflict ("the object has been modified"), producing the intermittent patch errors described in the issue.

Changes

Converted the four remaining plain Get + mutate + Update sequences in internal/controller/receiver_controller_test.go to the read-modify-write retry idiom already used in other Flux controllers (e.g. kustomize-controller):

g.Eventually(func() error {
    if err := k8sClient.Get(context.Background(), client.ObjectKeyFromObject(receiver), resultR); err != nil {
        return err
    }
    resultR.Spec.Suspend = true
    return k8sClient.Update(context.Background(), resultR)
}, timeout, time.Second).Should(Succeed())

Sites changed:

• TestReceiverReconciler_Reconcile / "fails with secret not found error"
• TestReceiverReconciler_Reconcile / "handles reconcileAt"
• TestReceiverReconciler_Reconcile / "finalizes suspended object"
• TestReceiverReconciler_EventHandler / "doesn't update the URL on spec updates"

Audit of the remaining mutation sites in the test suite:

• The raw client.RawPatch(types.MergePatchType, ...) calls in the receiver tests do not send a resourceVersion and cannot conflict — this is the workaround the issue refers to as the "other option".
• The alert and provider tests read the object via Eventually/Get before patching, and patch.Helper issues its spec/metadata patch without an optimistic lock, so they cannot fail with conflict errors either.

No controller code is changed.

Testing

KUBEBUILDER_ASSETS=... go test ./internal/controller/ -run 'TestReceiverReconciler' -v   # PASS
KUBEBUILDER_ASSETS=... go test ./internal/controller/                                   # ok (all package tests)
KUBEBUILDER_ASSETS=... go test ./internal/controller/ -run 'TestReceiverReconciler_Reconcile' -count=5  # ok
go vet ./internal/controller/ && gofmt -l internal/controller/                          # clean

[stefanprodan]

LGTM

Thanks @jojinkb