1 files changed, 57 insertions, 0 deletions
diff --git a/dnsutil/dnsutil_test.go b/dnsutil/dnsutil_test.go
new file mode 100644
index 0000000..305485f
--- /dev/null
+++ b/dnsutil/dnsutil_test.go
@@ -0,0 +1,57 @@
+package dnsutil
+
+import (
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+func TestMinTTL(t *testing.T) {
+	var tests = []struct {
+		answer []dns.RR
+		ns     []dns.RR
+		extra  []dns.RR
+		ttl    time.Duration
+	}{
+		{
+			[]dns.RR{
+				&dns.A{Hdr: dns.RR_Header{Ttl: 3600}},
+				&dns.A{Hdr: dns.RR_Header{Ttl: 60}},
+			},
+			nil,
+			nil,
+			time.Minute,
+		},
+		{
+			[]dns.RR{&dns.A{Hdr: dns.RR_Header{Ttl: 60}}},
+			[]dns.RR{&dns.NS{Hdr: dns.RR_Header{Ttl: 30}}},
+			nil,
+			30 * time.Second,
+		},
+		{
+			[]dns.RR{&dns.A{Hdr: dns.RR_Header{Ttl: 60}}},
+			[]dns.RR{&dns.NS{Hdr: dns.RR_Header{Ttl: 30}}},
+			[]dns.RR{&dns.NS{Hdr: dns.RR_Header{Ttl: 10}}},
+			10 * time.Second,
+		},
+		{
+			[]dns.RR{&dns.A{Hdr: dns.RR_Header{Ttl: 60}}},
+			nil,
+			[]dns.RR{
+				&dns.OPT{Hdr: dns.RR_Header{Ttl: 10, Rrtype: dns.TypeOPT}}, // Ignored
+				&dns.A{Hdr: dns.RR_Header{Ttl: 30}},
+			},
+			30 * time.Second,
+		},
+	}
+	for i, tt := range tests {
+		msg := dns.Msg{}
+		msg.Answer = tt.answer
+		msg.Ns = tt.ns
+		msg.Extra = tt.extra
+		if got := MinTTL(&msg); got != tt.ttl {
+			t.Errorf("#%d: MinTTL(\n%s) = %s, want %s", i, msg.String(), got, tt.ttl)
+		}
+	}
+}