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package mru_test
import (
"slices"
"sync"
"testing"
"lindenii.org/go/furgit/internal/mru"
)
func set(keys ...string) map[string]struct{} {
present := make(map[string]struct{}, len(keys))
for _, key := range keys {
present[key] = struct{}{}
}
return present
}
func TestTouchMovesToFront(t *testing.T) {
t.Parallel()
order := mru.New[string]()
order.Sync(set("a", "b", "c"))
order.Touch("a")
if got := order.Keys(); len(got) == 0 || got[0] != "a" {
t.Fatalf("after Touch(a), order = %v, want a first", got)
}
order.Touch("b")
if got := order.Keys(); len(got) < 2 || got[0] != "b" || got[1] != "a" {
t.Fatalf("after Touch(b), order = %v, want [b a ...]", got)
}
}
func TestSyncDropsAbsentAndKeepsSurvivorOrder(t *testing.T) {
t.Parallel()
order := mru.New[string]()
order.Sync(set("a", "b", "c"))
// Establish a deterministic recency order: c, b, a.
order.Touch("a")
order.Touch("b")
order.Touch("c")
if got, want := order.Keys(), []string{"c", "b", "a"}; !slices.Equal(got, want) {
t.Fatalf("order = %v, want %v", got, want)
}
order.Sync(set("a", "c"))
if got, want := order.Keys(), []string{"c", "a"}; !slices.Equal(got, want) {
t.Fatalf("after Sync, order = %v, want %v", got, want)
}
}
func TestTouchAbsentIsNoOp(t *testing.T) {
t.Parallel()
order := mru.New[string]()
order.Sync(set("a", "b"))
order.Touch("a")
order.Touch("z")
if got := order.Keys(); order.Len() != 2 || got[0] != "a" {
t.Fatalf("after Touch(z), order = %v, want front a and len 2", got)
}
}
func TestKeysIsConsistentSnapshot(t *testing.T) {
t.Parallel()
order := mru.New[string]()
order.Sync(set("a", "b"))
snapshot := order.Keys()
order.Sync(set("c"))
got := slices.Clone(snapshot)
slices.Sort(got)
if want := []string{"a", "b"}; !slices.Equal(got, want) {
t.Fatalf("captured snapshot = %v, want %v despite later Sync", got, want)
}
if cur, want := order.Keys(), []string{"c"}; !slices.Equal(cur, want) {
t.Fatalf("current order = %v, want %v", cur, want)
}
}
func TestConcurrentTouchAndKeys(t *testing.T) {
t.Parallel()
order := mru.New[string]()
order.Sync(set("a", "b", "c", "d"))
var wg sync.WaitGroup
for range 8 {
wg.Go(func() {
for range 1000 {
for _, key := range order.Keys() {
order.Touch(key)
}
}
})
}
wg.Wait()
got := slices.Clone(order.Keys())
slices.Sort(got)
if want := []string{"a", "b", "c", "d"}; !slices.Equal(got, want) {
t.Fatalf("membership corrupted: %v", got)
}
}
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