add test for cache miss

cache/cache.go

@@ -69,12 +69,13 @@ func (sc *ScoreCache) Add(score float64, ip netip.Addr, ts time.Time) {
 func (lc *ScoreCache) Get(ip netip.Addr) (ServerScore, error) {
 	now := time.Now()
 	lc.mu.RLock()
-	defer lc.mu.RUnlock()
 
 	cachedScore, ok := lc.scores[ip]
 	if !ok {
+		lc.mu.RUnlock()
 		return ServerScore{}, newCacheMissError()
 	}
+	lc.mu.RUnlock()
 
 	if now.After(cachedScore.expiresAt) {
 		lc.delete(ip)

cache/cache_test.go

@@ -32,3 +32,18 @@ func TestCacheGet(t *testing.T) {
 		t.Fatalf("cache.Get(\"1.2.3.4\") = %f, want %f", score.Score, testFloat)
 	}
 }
+
+func TestCacheMiss(t *testing.T) {
+	now := time.Now()
+	const testFloat = 1.23456
+
+	expiredTime := now.Add(-(time.Minute * 10))
+
+	cache := NewLocalCache()
+	cache.Add(testFloat, netip.MustParseAddr("1.2.3.4"), expiredTime)
+
+	_, err := cache.Get(netip.MustParseAddr("1.2.3.4"))
+	if err == nil {
+		t.Fatalf("cache.Get(\"1.2.3.4\") = got nil, want error")
+	}
+}