From 275c434bb5b46a670ae0ac34053b9cc7a027422c Mon Sep 17 00:00:00 2001
From: Jakob Haahr Taankvist <jht@uber.com>
Date: Wed, 6 Nov 2024 13:34:35 +0100
Subject: [PATCH] Added tests for LRU cache (#1388)

What changed?
Added tests for the LRU cache in client

The tests checks the current behaviour. The current behaviour should work but especially the pin API seems very fragile.

Why?
Improve test coverage

How did you test it?

Potential risks
---
 internal/common/cache/lru_test.go | 74 +++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/internal/common/cache/lru_test.go b/internal/common/cache/lru_test.go
index daa62067c..a0d3794aa 100644
--- a/internal/common/cache/lru_test.go
+++ b/internal/common/cache/lru_test.go
@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestLRU(t *testing.T) {
@@ -62,6 +63,79 @@ func TestLRU(t *testing.T) {
 	assert.Nil(t, cache.Get("A"))
 }
 
+func TestExist(t *testing.T) {
+	cache := NewLRUWithInitialCapacity(5, 5)
+
+	assert.False(t, cache.Exist("A"))
+
+	cache.Put("A", "Foo")
+	assert.True(t, cache.Exist("A"))
+	assert.False(t, cache.Exist("B"))
+
+	cache.Put("B", "Bar")
+	assert.True(t, cache.Exist("B"))
+
+	cache.Delete("A")
+	assert.False(t, cache.Exist("A"))
+}
+
+func TestPutIfNotExistSuccess(t *testing.T) {
+	cache := New(2, nil)
+
+	existing, err := cache.PutIfNotExist("A", "Foo")
+	assert.NoError(t, err)
+	assert.Equal(t, "Foo", existing)
+
+	existing, err = cache.PutIfNotExist("A", "Bar")
+	assert.NoError(t, err)
+	assert.Equal(t, "Foo", existing)
+
+	assert.Equal(t, "Foo", cache.Get("A"))
+}
+
+func TestNoPutInPin(t *testing.T) {
+	cache := New(2, &Options{
+		Pin: true,
+	})
+
+	assert.Panics(t, func() {
+		cache.Put("A", "Foo")
+	})
+}
+
+func TestPinningTTL(t *testing.T) {
+	cache := New(3, &Options{
+		Pin: true,
+		TTL: time.Millisecond * 100,
+	}).(*lru)
+
+	currentTime := time.UnixMilli(123)
+	cache.now = func() time.Time { return currentTime }
+
+	// Add two elements so the cache is full
+	_, err := cache.PutIfNotExist("A", "Foo")
+	require.NoError(t, err)
+	_, err = cache.PutIfNotExist("B", "Bar")
+	require.NoError(t, err)
+
+	// Release B so it can be evicted
+	cache.Release("B")
+
+	currentTime = currentTime.Add(time.Millisecond * 300)
+	assert.Equal(t, "Foo", cache.Get("A"))
+
+	// B can be evicted, so we can add another element
+	_, err = cache.PutIfNotExist("C", "Baz")
+	require.NoError(t, err)
+
+	// A cannot be evicted since it's pinned, so we can't add another element
+	_, err = cache.PutIfNotExist("D", "Qux")
+	assert.ErrorContains(t, err, "Cache capacity is fully occupied with pinned elements")
+
+	// B is gone
+	assert.Nil(t, cache.Get("B"))
+}
+
 func TestLRUWithTTL(t *testing.T) {
 	cache := New(5, &Options{
 		TTL: time.Millisecond * 100,