Implement response cache

http/cache_test.go

@@ -0,0 +1,41 @@
+package http
+
+import (
+	"fmt"
+	"net"
+	"testing"
+)
+
+func TestCacheCapacity(t *testing.T) {
+	var tests = []struct {
+		addCount, capacity, size int
+	}{
+		{1, 0, 0},
+		{1, 2, 1},
+		{2, 2, 2},
+		{3, 2, 2},
+	}
+	for i, tt := range tests {
+		c := NewCache(tt.capacity)
+		var responses []*Response
+		for i := 0; i < tt.addCount; i++ {
+			ip := net.ParseIP(fmt.Sprintf("192.0.2.%d", i))
+			r := &Response{IP: ip}
+			responses = append(responses, r)
+			c.Set(ip, r)
+		}
+		if got := len(c.entries); got != tt.size {
+			t.Errorf("#%d: len(entries) = %d, want %d", i, got, tt.size)
+		}
+		if tt.capacity > 0 && tt.addCount > tt.capacity && tt.capacity == tt.size {
+			lastAdded := responses[tt.addCount-1]
+			if _, ok := c.Get(lastAdded.IP); !ok {
+				t.Errorf("#%d: Get(%s) = (_, %t), want (_, %t)", i, lastAdded.IP.String(), ok, !ok)
+			}
+			firstAdded := responses[0]
+			if _, ok := c.Get(firstAdded.IP); ok {
+				t.Errorf("#%d: Get(%s) = (_, %t), want (_, %t)", i, firstAdded.IP.String(), ok, !ok)
+			}
+		}
+	}
+}