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package lfucache
import (
"strconv"
"testing"
"github.com/dgrijalva/lfu-go"
"github.com/stretchr/testify/assert"
)
func TestNew(t *testing.T) {
t.Run("it returns a pointer to the cache when the cap is valid", func(t *testing.T) {
cache, err := New[int, string](2)
assert.NoError(t, err)
assert.IsType(t, &Cache[int, string]{}, cache)
})
t.Run("it returns ErrInvalidCap when the cap is 0", func(t *testing.T) {
_, err := New[int, string](0)
assert.EqualError(t, err, ErrInvalidCap.Error())
})
t.Run("it returns ErrInvalidCap when the cap is less than 0", func(t *testing.T) {
_, err := New[int, string](-2)
assert.Error(t, err)
assert.EqualError(t, err, ErrInvalidCap.Error())
})
}
func TestCache_Len(t *testing.T) {
t.Run("it returns the 0 when there are no items in the cache", func(t *testing.T) {
cache, err := New[int, string](4)
assert.NoError(t, err)
assert.Equal(t, 0, cache.Len())
})
t.Run("it returns the 3 when there are 3 items in the cache", func(t *testing.T) {
cache, err := New[string, int](4)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 1)
assert.NoError(t, err)
err = cache.Set("you", 1)
assert.NoError(t, err)
assert.Equal(t, 3, cache.Len())
})
t.Run("it returns the size of the cache after more than cap items have been inserted", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
assert.Equal(t, 2, cache.Len())
})
}
func TestCache_Cap(t *testing.T) {
t.Run("it returns the size of the cache after creation", func(t *testing.T) {
cache, err := New[string, int](34)
assert.NoError(t, err)
assert.Equal(t, 34, cache.Cap())
})
t.Run("it returns the size of the cache after items have been added in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("you", 1)
assert.NoError(t, err)
assert.Equal(t, 2, cache.Cap())
})
t.Run("it returns the size of the cache after more than cap items have been inserted", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
assert.Equal(t, 2, cache.Cap())
})
}
func TestCache_IsFull(t *testing.T) {
t.Run("it returns false after cache is initialised", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
assert.False(t, cache.IsFull())
})
t.Run("it returns true when the cache is full", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 1)
assert.NoError(t, err)
assert.True(t, cache.IsFull())
})
t.Run("it returns true after more than cap items have been inserted", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
assert.True(t, cache.IsFull())
})
}
func TestCache_IsEmpty(t *testing.T) {
t.Run("it returns true after cache is initialised", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
assert.True(t, cache.IsEmpty())
})
t.Run("int returns false when there are items in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
assert.False(t, cache.IsEmpty())
})
t.Run("int returns false when the cache is full", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("fine", 1)
assert.NoError(t, err)
assert.False(t, cache.IsEmpty())
})
t.Run("it returns false after more than cap items have been inserted", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
assert.False(t, cache.IsEmpty())
})
}
func TestCache_Set(t *testing.T) {
t.Run("it returns ErrInvalidCap when the cap rate is 0", func(t *testing.T) {
cache := &Cache[string, int]{}
err := cache.Set("how", 1)
assert.EqualError(t, err, ErrInvalidCap.Error())
})
t.Run("it returns ErrInvalidCap when the cap rate is < 0", func(t *testing.T) {
cache := &Cache[string, int]{cap: -1}
err := cache.Set("how", 1)
assert.EqualError(t, err, ErrInvalidCap.Error())
})
t.Run("it can set a nil value in the cache", func(t *testing.T) {
cache, err := New[string, *int](1)
assert.NoError(t, err)
err = cache.Set("how", nil)
assert.NoError(t, err)
})
t.Run("it doesn't add a new value if the key is already in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
key := "how"
err = cache.Set(key, 1)
assert.NoError(t, err)
err = cache.Set(key, 2)
assert.NoError(t, err)
val, err := cache.Get(key)
assert.NoError(t, err)
assert.Equal(t, 1, cache.Len())
assert.Equal(t, 2, val)
})
t.Run("it can insert more than cap values in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
assert.True(t, cache.IsFull())
assert.Equal(t, 2, cache.Len())
})
t.Run("it removes the LFU item in the cache when inserting above capacity", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
// incrementing the frequency
_, err = cache.Get("how")
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
_, err = cache.Get("are")
assert.EqualError(t, err, ErrCacheMiss.Error())
val, err := cache.Get("how")
assert.NoError(t, err)
assert.Equal(t, 1, val)
val, err = cache.Get("you")
assert.NoError(t, err)
assert.Equal(t, 3, val)
})
}
func TestCache_Get(t *testing.T) {
t.Run("it returns ErrCacheMiss if an item is not in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
_, err = cache.Get("are")
assert.EqualError(t, err, ErrCacheMiss.Error())
})
t.Run("it returns an item when it is in the cache", func(t *testing.T) {
cache, err := New[string, int](2)
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
val, err := cache.Get("are")
assert.NoError(t, err)
assert.Equal(t, 2, val)
})
t.Run("it can get a nil value in the cache", func(t *testing.T) {
cache, err := New[string, *int](1)
assert.NoError(t, err)
var value *int = nil
err = cache.Set("how", value)
assert.NoError(t, err)
val, err := cache.Get("how")
assert.NoError(t, err)
assert.Equal(t, value, val)
})
}
func TestInternalImplementation(t *testing.T) {
t.Run("the internal storage items length is equal to 1 when there is 1 item in the cache", func(t *testing.T) {
cache, err := New[string, int](3)
assert.NoError(t, err)
key := "how"
err = cache.Set(key, 1)
assert.NoError(t, err)
// incrementing the frequency
_, err = cache.Get(key)
assert.NoError(t, err)
// changing the value
err = cache.Set(key, 3)
assert.NoError(t, err)
assert.Equal(t, 1, cache.frequencyList.Len())
assert.Equal(t, 1, len(cache.lookupTable))
assert.Equal(t, 1, cache.frequencyList.Front().Value.(*frequencyListNode).list.Len())
})
// Testing the following implementation
// we add 5 items in the cache
//
// "how" => weight = 3
// "are" => weight = 1
// "you" => weight = 2
// "doing" => weight = 1
// "today" => weight = 2
//
// Since the cache has a capacity of 4, when we add the key "today",
// the LFU items in the cache are "are" and "doing" and when there's a conflict, the LRU (least recently used)
// item is deleted. In this case, the least recently used item which is "are" is deleted.
// The frequency list has 3 nodes now
// 1 => "doing" -> nil
// 2 => "you" -> "today" -> nil
// 3 => "how" -> nil
t.Run("the internal storage items length when inserting above capacity", func(t *testing.T) {
cache, err := New[string, int](4)
assert.NoError(t, err)
err = cache.Set("how", 1)
assert.NoError(t, err)
// incrementing the frequency to 3
_, err = cache.Get("how")
assert.NoError(t, err)
_, err = cache.Get("how")
assert.NoError(t, err)
err = cache.Set("are", 2)
assert.NoError(t, err)
err = cache.Set("you", 3)
assert.NoError(t, err)
// incrementing frequency to 2
_, err = cache.Get("you")
assert.NoError(t, err)
err = cache.Set("doing", 4)
assert.NoError(t, err)
err = cache.Set("today", 5)
assert.NoError(t, err)
// incrementing frequency to 2
_, err = cache.Get("today")
assert.NoError(t, err)
assert.Equal(t, 3, cache.frequencyList.Len())
assert.Equal(t, 4, len(cache.lookupTable))
assert.Equal(t, 1, cache.frequencyList.Front().Value.(*frequencyListNode).list.Len())
assert.Equal(t, 1, cache.frequencyList.Back().Value.(*frequencyListNode).list.Len())
assert.Equal(t, 2, cache.frequencyList.Front().Next().Value.(*frequencyListNode).list.Len())
_, err = cache.Get("are")
assert.EqualError(t, err, ErrCacheMiss.Error())
})
}
func BenchmarkCache(b *testing.B) {
cache, err := New[string, int](100)
if err != nil {
b.Fatal(err.Error())
}
for i := 0; i < b.N; i++ {
for j := 0; j < 1000; j++ {
err = cache.Set(strconv.Itoa(i), j)
if err != nil {
b.Fatal(err.Error())
}
_, err = cache.Get(strconv.Itoa(i))
if err != nil {
b.Fatal(err.Error())
}
}
}
}
func BenchmarkOther(b *testing.B) {
cache := lfu.New()
for i := 0; i < b.N; i++ {
for j := 0; j < 1000; j++ {
if j >= 100 {
cache.Evict(1)
}
cache.Set(strconv.Itoa(i), j)
cache.Get(strconv.Itoa(i))
}
}
}