tests: add SortAndCheck helper (#926)

There was quite some code duplication in a lot of tests to check if
an answer was considered Ok. Created a test.SortAndCheck helper function
that takes care of this.

middleware/etcd/lookup_test.go

@@ -5,7 +5,6 @@ package etcd
 import (
 	"context"
 	"encoding/json"
-	"sort"
 	"testing"
 	"time"
 
@@ -267,23 +266,7 @@ func TestLookup(t *testing.T) {
 		etc.ServeDNS(ctxt, rec, m)
 
 		resp := rec.Msg
-		sort.Sort(test.RRSet(resp.Answer))
-		sort.Sort(test.RRSet(resp.Ns))
-		sort.Sort(test.RRSet(resp.Extra))
-
-		if !test.Header(t, tc, resp) {
-			t.Logf("%v\n", resp)
-			continue
-		}
-		if !test.Section(t, tc, test.Answer, resp.Answer) {
-			t.Logf("%v\n", resp)
-		}
-		if !test.Section(t, tc, test.Ns, resp.Ns) {
-			t.Logf("%v\n", resp)
-		}
-		if !test.Section(t, tc, test.Extra, resp.Extra) {
-			t.Logf("%v\n", resp)
-		}
+		test.SortAndCheck(t, resp, tc)
 	}
 }