@@ 17,6 17,7 @@ import (
 
 // TokenReader returns a reader for the XML encoding of v.
 func TokenReader(v interface{}) (xml.TokenReader, error) {
+	// If the payload to marshal is already a TokenReader, just return it.
 	if r, ok := v.(xml.TokenReader); ok {
 		return r, nil
 	}

@@ 5,9 5,13 @@
 package marshal_test
 
 import (
+	"bytes"
 	"encoding/xml"
+	"fmt"
+	"reflect"
 	"testing"
 
+	"mellium.im/xmlstream"
 	"mellium.im/xmpp/internal/marshal"
 	"mellium.im/xmpp/stanza"
 )


@@ 25,7 29,66 @@ func (wf *testWriteFlusher) Flush() error {
 	return nil
 }
 
-func TestFlushes(t *testing.T) {
+type noopTokenWriter struct{}
+
+func (noopTokenWriter) EncodeToken(xml.Token) error { return nil }
+
+type errTokenWriter struct{}
+
+func (errTokenWriter) EncodeToken(xml.Token) error { return bytes.ErrTooLarge }
+
+var simpleIn = struct {
+	XMLName xml.Name `xml:"space local"`
+}{}
+
+var encodeTestCases = [...]struct {
+	w       xmlstream.TokenWriter
+	v       interface{}
+	err     error
+	errType error
+}{
+	0: {
+		w:       nil,
+		v:       struct{}{},
+		errType: &xml.UnsupportedTypeError{},
+	},
+	1: {
+		w: noopTokenWriter{},
+		v: simpleIn,
+	},
+	2: {
+		w:   errTokenWriter{},
+		v:   simpleIn,
+		err: bytes.ErrTooLarge,
+	},
+}
+
+func TestEncode(t *testing.T) {
+	for i, tc := range encodeTestCases {
+		t.Run(fmt.Sprintf("%d/EncodeXML", i), func(t *testing.T) {
+			err := marshal.EncodeXML(tc.w, tc.v)
+			switch {
+			case tc.err != nil && err != tc.err:
+				t.Errorf("unexpected error: want=%v, got=%v", tc.err, err)
+			case tc.errType != nil && reflect.TypeOf(err) != reflect.TypeOf(tc.errType):
+				t.Errorf("error of wrong type: want=%T, got=%T", tc.errType, err)
+			}
+		})
+		t.Run(fmt.Sprintf("%d/EncodeXMLElement", i), func(t *testing.T) {
+			err := marshal.EncodeXMLElement(tc.w, tc.v, xml.StartElement{
+				Name: xml.Name{Space: "space", Local: "local"},
+			})
+			switch {
+			case tc.err != nil && err != tc.err:
+				t.Errorf("unexpected error: want=%v, got=%v", tc.err, err)
+			case tc.errType != nil && reflect.TypeOf(err) != reflect.TypeOf(tc.errType):
+				t.Errorf("error of wrong type: want=%T, got=%T", tc.errType, err)
+			}
+		})
+	}
+}
+
+func TestFlusher(t *testing.T) {
 	t.Run("EncodeXML", func(t *testing.T) {
 		f := &testWriteFlusher{}
 		if err := marshal.EncodeXML(f, 1); err != nil {


@@ 50,7 113,6 @@ func TestFlushes(t *testing.T) {
 }
 
 func TestMarshalTokenReader(t *testing.T) {
-	// If the payload to marshal is already a TokenReader, just return it.
 	r := stanza.IQ{}.Wrap(nil)
 	rr, err := marshal.TokenReader(r)
 	if err != nil {