plugin/file: add CAA record test case (#5219)

Signed-off-by: xuweiwei <xuweiwei_yewu@cmss.chinamobile.com>

plugin/file/lookup_test.go

@@ -139,6 +139,13 @@ var dnsTestCases = []test.Case{
 		},
 		Ns: miekAuth,
 	},
+	{
+		Qname: "caa.miek.nl.", Qtype: dns.TypeCAA,
+		Answer: []dns.RR{
+			test.CAA(`caa.miek.nl.  1800	IN	CAA  0 issue letsencrypt.org`),
+		},
+		Ns: miekAuth,
+	},
 }
 
 const (
@@ -244,4 +251,5 @@ srv		IN	SRV     10 10 8080 a.miek.nl.
 mx		IN	MX      10 a.miek.nl.
 
 txt     IN	TXT     "v=spf1 a mx ~all"
+caa     IN  CAA    0 issue letsencrypt.org
 ext-cname   IN   CNAME  example.com.`

plugin/test/helpers.go

@@ -82,6 +82,9 @@ func PTR(rr string) *dns.PTR { r, _ := dns.NewRR(rr); return r.(*dns.PTR) }
 // TXT returns a TXT record from rr. It panics on errors.
 func TXT(rr string) *dns.TXT { r, _ := dns.NewRR(rr); return r.(*dns.TXT) }
 
+// CAA returns a CAA record from rr. It panics on errors.
+func CAA(rr string) *dns.CAA { r, _ := dns.NewRR(rr); return r.(*dns.CAA) }
+
 // HINFO returns a HINFO record from rr. It panics on errors.
 func HINFO(rr string) *dns.HINFO { r, _ := dns.NewRR(rr); return r.(*dns.HINFO) }