03_pods_test.go

package playing

import (
	"iter"
	"maps"
	"slices"
	"testing"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
)

var pods = []corev1.Pod{
	{
		ObjectMeta: metav1.ObjectMeta{
			Name: "pod-1",
			UID:  types.UID("11111111-1111-1111-1111-111111111111"),
			Annotations: map[string]string{
				"pick-me": "true",
			},
		},
	},
	{
		ObjectMeta: metav1.ObjectMeta{
			Name: "pod-2",
			UID:  types.UID("222222222-2222-2222-2222-22222222222"),
		},
	},
	{
		ObjectMeta: metav1.ObjectMeta{
			Name: "pod-3",
			UID:  types.UID("33333333-3333-3333-3333-333333333333"),
			Annotations: map[string]string{
				"pick-me": "true",
			},
		},
	},
	{
		ObjectMeta: metav1.ObjectMeta{
			Name: "pod-4",
			UID:  types.UID("444444444-4444-4444-4444-44444444444"),
		},
	},
}

func filter[T any](seq iter.Seq[T], filterFn func(T) bool) iter.Seq[T] {
	return func(yield func(T) bool) {
		for v := range seq {
			if filterFn(v) {
				if !yield(v) {
					return
				}
			}
		}
	}
}

func TestFilterSlice(t *testing.T) {
	itr := slices.Values(pods)
	filteredItr := filter(itr, func(pod corev1.Pod) bool {
		return metav1.HasAnnotation(pod.ObjectMeta, "pick-me")
	})

	for v := range filteredItr {
		t.Logf("%#v\n", v)
	}

	s := slices.Collect(filteredItr)
	t.Logf("%#v\n", s)
}

func transform[K, V1, V2 any](seq iter.Seq[V1], transFn func(V1) (K, V2)) iter.Seq2[K, V2] {
	return func(yield func(K, V2) bool) {
		for v1 := range seq {
			if !yield(transFn(v1)) {
				return
			}
		}
	}
}

func TestSliceToMap(t *testing.T) {
	itr := slices.Values(pods)
	podsByName := maps.Collect(transform(itr, func(pod corev1.Pod) (string, corev1.Pod) {
		return pod.Name, pod
	}))

	t.Logf("%#v\n", podsByName)

	nameByUID := maps.Collect(transform(itr, func(pod corev1.Pod) (types.UID, string) {
		return pod.UID, pod.Name
	}))
	t.Logf("%#v\n", nameByUID)
}

func TestFilterAndTransform(t *testing.T) {
	pickMe := func(pod corev1.Pod) bool {
		return metav1.HasAnnotation(pod.ObjectMeta, "pick-me")
	}

	podNameUID := func(pod corev1.Pod) (string, types.UID) {
		return pod.Name, pod.UID
	}

	m := maps.Collect(
		transform(
			filter(
				slices.Values(pods),
				pickMe),
			podNameUID),
	)
	t.Logf("%#v\n", m)
}