func Generate(req *plugin.CodeGeneratorRequest) *plugin.CodeGeneratorResponse {
	// Begin by allocating a generator. The request and response structures are stored there
	// so we can do error handling easily - the response structure contains the field to
	// report failure.
	g := generator.New()
	g.Request = req

	g.CommandLineParameters(g.Request.GetParameter())

	// Create a wrapped version of the Descriptors and EnumDescriptors that
	// point to the file that defines them.
	g.WrapTypes()

	g.SetPackageNames()
	g.BuildTypeNameMap()

	g.GenerateAllFiles()

	gtest := generator.New()

	data, err := proto.Marshal(req)
	if err != nil {
		g.Error(err, "failed to marshal modified proto")
	}
	if err := proto.Unmarshal(data, gtest.Request); err != nil {
		g.Error(err, "parsing modified proto")
	}

	if len(gtest.Request.FileToGenerate) == 0 {
		gtest.Fail("no files to generate")
	}

	gtest.CommandLineParameters(gtest.Request.GetParameter())

	// Create a wrapped version of the Descriptors and EnumDescriptors that
	// point to the file that defines them.
	gtest.WrapTypes()

	gtest.SetPackageNames()
	gtest.BuildTypeNameMap()

	gtest.GeneratePlugin(testgen.NewPlugin())

	for i := 0; i < len(gtest.Response.File); i++ {
		if strings.Contains(*gtest.Response.File[i].Content, `//These tests are generated by github.com/andres-erbsen/protobuf/plugin/testgen`) {
			gtest.Response.File[i].Name = proto.String(strings.Replace(*gtest.Response.File[i].Name, ".pb.go", "pb_test.go", -1))
			g.Response.File = append(g.Response.File, gtest.Response.File[i])
		}
	}

	for i := 0; i < len(g.Response.File); i++ {
		formatted, err := format.Source([]byte(g.Response.File[i].GetContent()))
		if err != nil {
			g.Error(err, "go format error")
		}
		fmts := string(formatted)
		g.Response.File[i].Content = &fmts
	}
	return g.Response
}

func TestZeroLengthOptionalBytes(t *testing.T) {
	roundtrip := func(f *Foo) *Foo {
		data, err := proto.Marshal(f)
		if err != nil {
			panic(err)
		}
		newF := &Foo{}
		err = proto.Unmarshal(data, newF)
		if err != nil {
			panic(err)
		}
		return newF
	}

	f := &Foo{}
	roundtrippedF := roundtrip(f)
	if roundtrippedF.Bar != nil {
		t.Fatalf("should be nil")
	}

	f.Bar = []byte{}
	roundtrippedF = roundtrip(f)
	if roundtrippedF.Bar == nil {
		t.Fatalf("should not be nil")
	}
	if len(roundtrippedF.Bar) != 0 {
		t.Fatalf("should be empty")
	}
}

func TestGetExtensionStability(t *testing.T) {
	check := func(m *pb.MyMessage) bool {
		ext1, err := proto.GetExtension(m, pb.E_Ext_More)
		if err != nil {
			t.Fatalf("GetExtension() failed: %s", err)
		}
		ext2, err := proto.GetExtension(m, pb.E_Ext_More)
		if err != nil {
			t.Fatalf("GetExtension() failed: %s", err)
		}
		return ext1 == ext2
	}
	msg := &pb.MyMessage{Count: proto.Int32(4)}
	ext0 := &pb.Ext{}
	if err := proto.SetExtension(msg, pb.E_Ext_More, ext0); err != nil {
		t.Fatalf("Could not set ext1: %s", ext0)
	}
	if !check(msg) {
		t.Errorf("GetExtension() not stable before marshaling")
	}
	bb, err := proto.Marshal(msg)
	if err != nil {
		t.Fatalf("Marshal() failed: %s", err)
	}
	msg1 := &pb.MyMessage{}
	err = proto.Unmarshal(bb, msg1)
	if err != nil {
		t.Fatalf("Unmarshal() failed: %s", err)
	}
	if !check(msg1) {
		t.Errorf("GetExtension() not stable after unmarshaling")
	}
}

//See another version of this test in proto/extensions_test.go
func TestGetExtensionStability(t *testing.T) {
	check := func(m *NoExtensionsMap) bool {
		ext1, err := proto.GetExtension(m, E_FieldB1)
		if err != nil {
			t.Fatalf("GetExtension() failed: %s", err)
		}
		ext2, err := proto.GetExtension(m, E_FieldB1)
		if err != nil {
			t.Fatalf("GetExtension() failed: %s", err)
		}
		return ext1.(*NinOptNative).Equal(ext2)
	}
	msg := &NoExtensionsMap{Field1: proto.Int64(2)}
	ext0 := &NinOptNative{Field1: proto.Float64(1)}
	if err := proto.SetExtension(msg, E_FieldB1, ext0); err != nil {
		t.Fatalf("Could not set ext1: %s", ext0)
	}
	if !check(msg) {
		t.Errorf("GetExtension() not stable before marshaling")
	}
	bb, err := proto.Marshal(msg)
	if err != nil {
		t.Fatalf("Marshal() failed: %s", err)
	}
	msg1 := &NoExtensionsMap{}
	err = proto.Unmarshal(bb, msg1)
	if err != nil {
		t.Fatalf("Unmarshal() failed: %s", err)
	}
	if !check(msg1) {
		t.Errorf("GetExtension() not stable after unmarshaling")
	}
}

func testSize(m interface {
	proto.Message
	Size() int
}, desc string, expected int) ([]byte, error) {
	data, err := proto.Marshal(m)
	if err != nil {
		return nil, err
	}
	protoSize := proto.Size(m)
	mSize := m.Size()
	lenData := len(data)
	if protoSize != mSize || protoSize != lenData || mSize != lenData {
		return nil, fmt.Errorf("%s proto.Size(m){%d} != m.Size(){%d} != len(data){%d}", desc, protoSize, mSize, lenData)
	}
	if got := protoSize; got != expected {
		return nil, fmt.Errorf("%s proto.Size(m) got %d expected %d", desc, got, expected)
	}
	if got := mSize; got != expected {
		return nil, fmt.Errorf("%s m.Size() got %d expected %d", desc, got, expected)
	}
	if got := lenData; got != expected {
		return nil, fmt.Errorf("%s len(data) got %d expected %d", desc, got, expected)
	}
	return data, nil
}

func (this *uint32Writer) WriteMsg(msg proto.Message) (err error) {
	var data []byte
	if m, ok := msg.(marshaler); ok {
		n := m.Size()
		if n >= len(this.buffer) {
			this.buffer = make([]byte, n)
		}
		_, err = m.MarshalTo(this.buffer)
		if err != nil {
			return err
		}
		data = this.buffer[:n]
	} else {
		data, err = proto.Marshal(msg)
		if err != nil {
			return err
		}
	}
	length := uint32(len(data))
	if err := binary.Write(this.w, this.byteOrder, &length); err != nil {
		return err
	}
	_, err = this.w.Write(data)
	return err
}

func TestRoundTripProto3(t *testing.T) {
	m := &pb.Message{
		Name:         "David",          // (2 | 1<<3): 0x0a 0x05 "David"
		Hilarity:     pb.Message_PUNS,  // (0 | 2<<3): 0x10 0x01
		HeightInCm:   178,              // (0 | 3<<3): 0x18 0xb2 0x01
		Data:         []byte("roboto"), // (2 | 4<<3): 0x20 0x06 "roboto"
		ResultCount:  47,               // (0 | 7<<3): 0x38 0x2f
		TrueScotsman: true,             // (0 | 8<<3): 0x40 0x01
		Score:        8.1,              // (5 | 9<<3): 0x4d <8.1>

		Key: []uint64{1, 0xdeadbeef},
		Nested: &pb.Nested{
			Bunny: "Monty",
		},
	}
	t.Logf(" m: %v", m)

	b, err := proto.Marshal(m)
	if err != nil {
		t.Fatalf("proto.Marshal: %v", err)
	}
	t.Logf(" b: %q", b)

	m2 := new(pb.Message)
	if err := proto.Unmarshal(b, m2); err != nil {
		t.Fatalf("proto.Unmarshal: %v", err)
	}
	t.Logf("m2: %v", m2)

	if !proto.Equal(m, m2) {
		t.Errorf("proto.Equal returned false:\n m: %v\nm2: %v", m, m2)
	}
}

func TestUnmarshalPartiallyPopulatedOptionalFieldsFails(t *testing.T) {
	// Fill in all fields, then randomly remove one.
	dataOut := &test.NinOptNative{
		Field1:  proto.Float64(0),
		Field2:  proto.Float32(0),
		Field3:  proto.Int32(0),
		Field4:  proto.Int64(0),
		Field5:  proto.Uint32(0),
		Field6:  proto.Uint64(0),
		Field7:  proto.Int32(0),
		Field8:  proto.Int64(0),
		Field9:  proto.Uint32(0),
		Field10: proto.Int32(0),
		Field11: proto.Uint64(0),
		Field12: proto.Int64(0),
		Field13: proto.Bool(false),
		Field14: proto.String("0"),
		Field15: []byte("0"),
	}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	fieldName := "Field" + strconv.Itoa(r.Intn(15)+1)
	field := reflect.ValueOf(dataOut).Elem().FieldByName(fieldName)
	fieldType := field.Type()
	field.Set(reflect.Zero(fieldType))
	encodedMessage, err := proto.Marshal(dataOut)
	if err != nil {
		t.Fatalf("Unexpected error when marshalling dataOut: %v", err)
	}
	dataIn := NidOptNative{}
	err = proto.Unmarshal(encodedMessage, &dataIn)
	if err.Error() != `proto: required field "`+fieldName+`" not set` {
		t.Fatalf(`err.Error() != "proto: required field "`+fieldName+`" not set"; was "%s" instead`, err.Error())
	}
}

func TestKeyserverStepProto(t *testing.T) {
	popr := math_rand.New(math_rand.NewSource(time.Now().UnixNano()))
	p := NewPopulatedKeyserverStep(popr, false)
	data, err := github_com_andres_erbsen_protobuf_proto.Marshal(p)
	if err != nil {
		panic(err)
	}
	msg := &KeyserverStep{}
	if err := github_com_andres_erbsen_protobuf_proto.Unmarshal(data, msg); err != nil {
		panic(err)
	}
	littlefuzz := make([]byte, len(data))
	copy(littlefuzz, data)
	for i := range data {
		data[i] = byte(popr.Intn(256))
	}
	if err := p.VerboseEqual(msg); err != nil {
		t.Fatalf("%#v !VerboseProto %#v, since %v", msg, p, err)
	}
	if !p.Equal(msg) {
		t.Fatalf("%#v !Proto %#v", msg, p)
	}
	if len(littlefuzz) > 0 {
		fuzzamount := 100
		for i := 0; i < fuzzamount; i++ {
			littlefuzz[popr.Intn(len(littlefuzz))] = byte(popr.Intn(256))
			littlefuzz = append(littlefuzz, byte(popr.Intn(256)))
		}
		// shouldn't panic
		_ = github_com_andres_erbsen_protobuf_proto.Unmarshal(littlefuzz, msg)
	}
}

func (this *varintWriter) WriteMsg(msg proto.Message) (err error) {
	var data []byte
	if m, ok := msg.(marshaler); ok {
		n := m.Size()
		if n >= len(this.buffer) {
			this.buffer = make([]byte, n)
		}
		_, err = m.MarshalTo(this.buffer)
		if err != nil {
			return err
		}
		data = this.buffer[:n]
	} else {
		data, err = proto.Marshal(msg)
		if err != nil {
			return err
		}
	}
	length := uint64(len(data))
	n := binary.PutUvarint(this.lenBuf, length)
	_, err = this.w.Write(this.lenBuf[:n])
	if err != nil {
		return err
	}
	_, err = this.w.Write(data)
	return err
}

func TestMessageProto(t *testing.T) {
	seed := time.Now().UnixNano()
	popr := math_rand.New(math_rand.NewSource(seed))
	p := NewPopulatedMessage(popr, false)
	data, err := github_com_gogo_protobuf_proto.Marshal(p)
	if err != nil {
		t.Fatalf("seed = %d, err = %v", seed, err)
	}
	msg := &Message{}
	if err := github_com_gogo_protobuf_proto.Unmarshal(data, msg); err != nil {
		t.Fatalf("seed = %d, err = %v", seed, err)
	}
	littlefuzz := make([]byte, len(data))
	copy(littlefuzz, data)
	for i := range data {
		data[i] = byte(popr.Intn(256))
	}
	if err := p.VerboseEqual(msg); err != nil {
		t.Fatalf("seed = %d, %#v !VerboseProto %#v, since %v", seed, msg, p, err)
	}
	if !p.Equal(msg) {
		t.Fatalf("seed = %d, %#v !Proto %#v", seed, msg, p)
	}
	if len(littlefuzz) > 0 {
		fuzzamount := 100
		for i := 0; i < fuzzamount; i++ {
			littlefuzz[popr.Intn(len(littlefuzz))] = byte(popr.Intn(256))
			littlefuzz = append(littlefuzz, byte(popr.Intn(256)))
		}
		// shouldn't panic
		_ = github_com_gogo_protobuf_proto.Unmarshal(littlefuzz, msg)
	}
}

func newTestMessage() *pb.MyMessage {
	msg := &pb.MyMessage{
		Count: proto.Int32(42),
		Name:  proto.String("Dave"),
		Quote: proto.String(`"I didn't want to go."`),
		Pet:   []string{"bunny", "kitty", "horsey"},
		Inner: &pb.InnerMessage{
			Host:      proto.String("footrest.syd"),
			Port:      proto.Int32(7001),
			Connected: proto.Bool(true),
		},
		Others: []*pb.OtherMessage{
			{
				Key:   proto.Int64(0xdeadbeef),
				Value: []byte{1, 65, 7, 12},
			},
			{
				Weight: proto.Float32(6.022),
				Inner: &pb.InnerMessage{
					Host: proto.String("lesha.mtv"),
					Port: proto.Int32(8002),
				},
			},
		},
		Bikeshed: pb.MyMessage_BLUE.Enum(),
		Somegroup: &pb.MyMessage_SomeGroup{
			GroupField: proto.Int32(8),
		},
		// One normally wouldn't do this.
		// This is an undeclared tag 13, as a varint (wire type 0) with value 4.
		XXX_unrecognized: []byte{13<<3 | 0, 4},
	}
	ext := &pb.Ext{
		Data: proto.String("Big gobs for big rats"),
	}
	if err := proto.SetExtension(msg, pb.E_Ext_More, ext); err != nil {
		panic(err)
	}
	greetings := []string{"adg", "easy", "cow"}
	if err := proto.SetExtension(msg, pb.E_Greeting, greetings); err != nil {
		panic(err)
	}

	// Add an unknown extension. We marshal a pb.Ext, and fake the ID.
	b, err := proto.Marshal(&pb.Ext{Data: proto.String("3G skiing")})
	if err != nil {
		panic(err)
	}
	b = append(proto.EncodeVarint(201<<3|proto.WireBytes), b...)
	proto.SetRawExtension(msg, 201, b)

	// Extensions can be plain fields, too, so let's test that.
	b = append(proto.EncodeVarint(202<<3|proto.WireVarint), 19)
	proto.SetRawExtension(msg, 202, b)

	return msg
}

func TestIssue42Order(t *testing.T) {
	unordered := NewPopulatedUnorderedFields(math_rand.New(math_rand.NewSource(time.Now().UnixNano())), false)
	udata, err := proto.Marshal(unordered)
	if err != nil {
		t.Fatal(err)
	}
	ordered := &OrderedFields{}
	if err := proto.Unmarshal(udata, ordered); err != nil {
		t.Fatal(err)
	}
	data, err := proto.Marshal(ordered)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(udata, data) {
		t.Fatalf("expected data to be marshaled in the same order, please sort fields before marshaling")
	}
}

func TestOldNewOldNew(t *testing.T) {
	popr := math_rand.New(math_rand.NewSource(time.Now().UnixNano()))
	older := NewPopulatedOldWithGroup(popr, true)
	data1, err := proto.Marshal(older)
	if err != nil {
		panic(err)
	}
	newer := &NewNoGroup{}
	if err := proto.Unmarshal(data1, newer); err != nil {
		panic(err)
	}
	data2, err := proto.Marshal(newer)
	if err != nil {
		panic(err)
	}
	bluer := &OldWithGroup{}
	if err := proto.Unmarshal(data2, bluer); err != nil {
		panic(err)
	}
	if err := older.VerboseEqual(bluer); err != nil {
		t.Fatalf("%#v !VerboseProto %#v, since %v", older, bluer, err)
	}

	data3, err := proto.Marshal(bluer)
	if err != nil {
		panic(err)
	}
	purple := &NewNoGroup{}
	if err := proto.Unmarshal(data3, purple); err != nil {
		panic(err)
	}
	data4, err := proto.Marshal(purple)
	if err != nil {
		panic(err)
	}
	magenta := &OldWithGroup{}
	if err := proto.Unmarshal(data4, magenta); err != nil {
		panic(err)
	}
	if err := older.VerboseEqual(magenta); err != nil {
		t.Fatalf("%#v !VerboseProto %#v, since %v", older, magenta, err)
	}
}

//http://code.google.com/p/goprotobuf/issues/detail?id=39
func TestBugUint32VarintSize(t *testing.T) {
	temp := uint32(math.MaxUint32)
	n := &NinOptNative{}
	n.Field5 = &temp
	data, err := proto.Marshal(n)
	if err != nil {
		panic(err)
	}
	if len(data) != 6 {
		t.Fatalf("data should be length 6, but its %#v", data)
	}
}

func TestMarshalToSucceedsWhenRequiredFieldIsPresent(t *testing.T) {
	data := RequiredExample{
		TheRequiredString: proto.String("present"),
	}
	buf, err := proto.Marshal(&data)
	if err != nil {
		t.Fatalf("err != nil; was %v instead", err)
	}
	if len(buf) == 0 {
		t.Fatalf(`len(buf) == 0; expected nonzero`)
	}
}

func Write(resp *plugin.CodeGeneratorResponse) {
	g := generator.New()
	// Send back the results.
	data, err := proto.Marshal(resp)
	if err != nil {
		g.Error(err, "failed to marshal output proto")
	}
	_, err = os.Stdout.Write(data)
	if err != nil {
		g.Error(err, "failed to write output proto")
	}
}

func TestMarshalToErrorsWhenRequiredFieldIsNotPresent(t *testing.T) {
	data := RequiredExample{}
	buf, err := proto.Marshal(&data)
	if err == nil {
		t.Fatalf("err == nil; was %v instead", err)
	}
	if err.Error() != `proto: required field "theRequiredString" not set` {
		t.Fatalf(`err.Error() != "proto: required field "theRequiredString" not set"; was "%s" instead`, err.Error())
	}
	if len(buf) != 0 {
		t.Fatalf(`len(buf) != 0; was %d instead`, len(buf))
	}
}

func TestUnmarshalPopulatedOptionalFieldsAsRequiredSucceeds(t *testing.T) {
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	dataOut := test.NewPopulatedNidOptNative(r, true)
	encodedMessage, err := proto.Marshal(dataOut)
	if err != nil {
		t.Fatalf("Unexpected error when marshalling dataOut: %v", err)
	}
	dataIn := NidOptNative{}
	err = proto.Unmarshal(encodedMessage, &dataIn)
	if err != nil {
		t.Fatalf("err != nil; was %v instead", err)
	}
}

func TestBugZeroLengthSliceSize(t *testing.T) {
	n := &NinRepPackedNative{
		Field8: []int64{},
	}
	size := n.Size()
	data, err := proto.Marshal(n)
	if err != nil {
		panic(err)
	}
	if len(data) != size {
		t.Fatalf("expected %v, but got %v", len(data), size)
	}
}