diff --git a/lfu_cache_test.go b/lfu_cache_test.go
new file mode 100644
index 0000000..7cef26b
--- /dev/null
+++ b/lfu_cache_test.go
@@ -0,0 +1,173 @@
+package incache
+
+import (
+	"testing"
+	"time"
+)
+
+func TestLFUCache_SetGet(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	cache.Set(1, "one")
+	cache.Set(2, "two")
+
+	if value, ok := cache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one', got '%v'", value)
+	}
+
+	if value, ok := cache.Get(2); !ok || value != "two" {
+		t.Errorf("Expected to get 'two', got '%v'", value)
+	}
+}
+
+func TestLFUCache_Eviction(t *testing.T) {
+	cache := NewLFU[int, string](2)
+
+	cache.Set(1, "one")
+	cache.Set(2, "two")
+	cache.Set(3, "three")
+
+	if _, ok := cache.Get(1); ok {
+		t.Logf("all: %v\n", cache.GetAll())
+		t.Errorf("Expected 1 to be evicted")
+	}
+
+	if value, ok := cache.Get(2); !ok || value != "two" {
+		t.Errorf("Expected to get 'two', got '%v'", value)
+	}
+
+	if value, ok := cache.Get(3); !ok || value != "three" {
+		t.Errorf("Expected to get 'three', got '%v'", value)
+	}
+}
+
+func TestLFUCache_SetWithTimeout(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	cache.SetWithTimeout(1, "one", 2*time.Millisecond)
+	time.Sleep(1 * time.Millisecond)
+
+	if value, ok := cache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one', got '%v'", value)
+	}
+
+	time.Sleep(2 * time.Millisecond)
+
+	if v, ok := cache.Get(1); ok {
+		t.Logf("v: %v | ok: %v\n", v, ok)
+		t.Errorf("Expected 1 to be expired")
+	}
+}
+
+func TestLFUCache_NotFoundSet(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	if !cache.NotFoundSet(1, "one") {
+		t.Errorf("Expected to set key 1")
+	}
+
+	if cache.NotFoundSet(1, "one") {
+		t.Errorf("Expected not to set key 1 again")
+	}
+
+	if value, ok := cache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one', got '%v'", value)
+	}
+}
+
+func TestLFUCache_TransferTo(t *testing.T) {
+	srcCache := NewLFU[int, string](10)
+	dstCache := NewLFU[int, string](10)
+
+	srcCache.Set(1, "one")
+	srcCache.Set(2, "two")
+	srcCache.TransferTo(dstCache)
+
+	if _, ok := srcCache.Get(1); ok {
+		t.Errorf("Expected 1 to be transferred")
+	}
+
+	if value, ok := dstCache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one' from dstCache, got '%v'", value)
+	}
+
+	if value, ok := dstCache.Get(2); !ok || value != "two" {
+		t.Errorf("Expected to get 'two' from dstCache, got '%v'", value)
+	}
+}
+
+func TestLFUCache_CopyTo(t *testing.T) {
+	srcCache := NewLFU[int, string](10)
+	dstCache := NewLFU[int, string](10)
+
+	srcCache.Set(1, "one")
+	srcCache.Set(2, "two")
+	srcCache.CopyTo(dstCache)
+
+	if value, ok := srcCache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one' from srcCache, got '%v'", value)
+	}
+
+	if value, ok := dstCache.Get(1); !ok || value != "one" {
+		t.Errorf("Expected to get 'one' from dstCache, got '%v'", value)
+	}
+
+	if value, ok := dstCache.Get(2); !ok || value != "two" {
+		t.Errorf("Expected to get 'two' from dstCache, got '%v'", value)
+	}
+}
+
+func TestLFUCache_Keys(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	cache.Set(1, "one")
+	cache.Set(2, "two")
+	cache.Set(3, "three")
+
+	keys := cache.Keys()
+
+	expectedKeys := map[int]bool{
+		1: true,
+		2: true,
+		3: true,
+	}
+
+	for _, key := range keys {
+		if !expectedKeys[key] {
+			t.Errorf("Unexpected key %v", key)
+		}
+	}
+}
+
+func TestLFUCache_Purge(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	cache.Set(1, "one")
+	cache.Set(2, "two")
+	cache.Purge()
+
+	if value, ok := cache.Get(1); ok {
+		t.Errorf("Expected cache to be purged, got '%v'", value)
+	}
+
+	if value, ok := cache.Get(2); ok {
+		t.Errorf("Expected cache to be purged, got '%v'", value)
+	}
+}
+
+func TestLFUCache_Delete(t *testing.T) {
+	cache := NewLFU[int, string](10)
+
+	cache.Set(1, "one")
+	cache.Set(2, "two")
+
+	cache.Delete(1)
+
+	if value, ok := cache.Get(1); ok {
+		t.Errorf("Expected key 1 to be deleted, got '%v'", value)
+	}
+
+	if value, ok := cache.Get(2); !ok || value != "two" {
+		t.Errorf("Expected to get 'two', got '%v'", value)
+	}
+}