Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/dnstap/test/helpers.go

@@ -0,0 +1,80 @@
+package test
+
+import (
+	"net"
+	"reflect"
+
+	"github.com/coredns/coredns/plugin/dnstap/msg"
+
+	tap "github.com/dnstap/golang-dnstap"
+	"golang.org/x/net/context"
+)
+
+// Context is a message trap.
+type Context struct {
+	context.Context
+	TrapTapper
+}
+
+// TestingData returns the Data matching coredns/test.ResponseWriter.
+func TestingData() (d *msg.Data) {
+	d = &msg.Data{
+		SocketFam:   tap.SocketFamily_INET,
+		SocketProto: tap.SocketProtocol_UDP,
+		Address:     net.ParseIP("10.240.0.1"),
+		Port:        40212,
+	}
+	return
+}
+
+type comp struct {
+	Type  *tap.Message_Type
+	SF    *tap.SocketFamily
+	SP    *tap.SocketProtocol
+	QA    []byte
+	RA    []byte
+	QP    *uint32
+	RP    *uint32
+	QTSec bool
+	RTSec bool
+	RM    []byte
+	QM    []byte
+}
+
+func toComp(m *tap.Message) comp {
+	return comp{
+		Type:  m.Type,
+		SF:    m.SocketFamily,
+		SP:    m.SocketProtocol,
+		QA:    m.QueryAddress,
+		RA:    m.ResponseAddress,
+		QP:    m.QueryPort,
+		RP:    m.ResponsePort,
+		QTSec: m.QueryTimeSec != nil,
+		RTSec: m.ResponseTimeSec != nil,
+		RM:    m.ResponseMessage,
+		QM:    m.QueryMessage,
+	}
+}
+
+// MsgEqual compares two dnstap messages ignoring timestamps.
+func MsgEqual(a, b *tap.Message) bool {
+	return reflect.DeepEqual(toComp(a), toComp(b))
+}
+
+// TrapTapper traps messages.
+type TrapTapper struct {
+	Trap []*tap.Message
+	Full bool
+}
+
+// TapMessage adds the message to the trap.
+func (t *TrapTapper) TapMessage(m *tap.Message) error {
+	t.Trap = append(t.Trap, m)
+	return nil
+}
+
+// TapBuilder returns a test msg.Builder.
+func (t *TrapTapper) TapBuilder() msg.Builder {
+	return msg.Builder{Full: t.Full}
+}