at-container-registry/pkg/appview/jetstream/endpoint_rotator_test.go

package jetstream

import (
	"sync"
	"testing"
)

func TestEndpointRotator_Current(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b", "c"})
	if got := r.Current(); got != "a" {
		t.Errorf("Current() = %q, want %q", got, "a")
	}
	// Calling Current again should not advance
	if got := r.Current(); got != "a" {
		t.Errorf("Current() second call = %q, want %q", got, "a")
	}
}

func TestEndpointRotator_Next(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b", "c"})
	if got := r.Next(); got != "b" {
		t.Errorf("Next() = %q, want %q", got, "b")
	}
	if got := r.Next(); got != "c" {
		t.Errorf("Next() = %q, want %q", got, "c")
	}
}

func TestEndpointRotator_WrapAround(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b"})
	r.Next() // -> b
	got := r.Next()
	if got != "a" {
		t.Errorf("Next() after wrap = %q, want %q", got, "a")
	}
}

func TestEndpointRotator_Reset(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b", "c"})
	r.Next() // -> b
	r.Next() // -> c
	r.Reset()
	if got := r.Current(); got != "a" {
		t.Errorf("Current() after Reset() = %q, want %q", got, "a")
	}
}

func TestEndpointRotator_Len(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b", "c"})
	if got := r.Len(); got != 3 {
		t.Errorf("Len() = %d, want 3", got)
	}
}

func TestEndpointRotator_SingleEndpoint(t *testing.T) {
	r := NewEndpointRotator([]string{"only"})
	if got := r.Current(); got != "only" {
		t.Errorf("Current() = %q, want %q", got, "only")
	}
	// Next on single endpoint wraps back to itself
	if got := r.Next(); got != "only" {
		t.Errorf("Next() = %q, want %q", got, "only")
	}
}

func TestEndpointRotator_PanicsOnEmpty(t *testing.T) {
	defer func() {
		if r := recover(); r == nil {
			t.Error("NewEndpointRotator(nil) did not panic")
		}
	}()
	NewEndpointRotator(nil)
}

func TestEndpointRotator_Concurrent(t *testing.T) {
	r := NewEndpointRotator([]string{"a", "b", "c", "d"})
	var wg sync.WaitGroup
	for range 100 {
		wg.Go(func() {
			_ = r.Current()
			_ = r.Next()
		})
	}
	wg.Wait()
	// No race detector failures = success
}