diff --git a/.travis.yml b/.travis.yml
index a78f196..816a977 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,6 @@ language: go
 dist: trusty
 
 go:
-  - 1.6
   - 1.7
   - 1.8
   - tip
diff --git a/usb/device.go b/usb/device.go
index ae5f3b5..86a0a31 100644
--- a/usb/device.go
+++ b/usb/device.go
@@ -122,9 +122,7 @@ func (d *Device) Close() error {
 }
 
 func (d *Device) OpenEndpoint(conf, iface, setup, epoint uint8) (Endpoint, error) {
-	end := &endpoint{
-		Device: d,
-	}
+	end := newEndpoint(d)
 
 	var setAlternate bool
 	for _, c := range d.Configs {
diff --git a/usb/endpoint.go b/usb/endpoint.go
index 0a3b174..a33dd15 100644
--- a/usb/endpoint.go
+++ b/usb/endpoint.go
@@ -17,7 +17,6 @@ package usb
 
 import (
 	"fmt"
-	"log"
 	"time"
 )
 
@@ -28,10 +27,22 @@ type Endpoint interface {
 	Info() EndpointInfo
 }
 
+type transferIntf interface {
+	submit() error
+	wait() (int, error)
+	free() error
+}
+
 type endpoint struct {
-	*Device
+	h *deviceHandle
+
 	InterfaceSetup
 	EndpointInfo
+
+	readTimeout  time.Duration
+	writeTimeout time.Duration
+
+	newUSBTransfer func([]byte, time.Duration) (transferIntf, error)
 }
 
 func (e *endpoint) Read(buf []byte) (int, error) {
@@ -39,7 +50,7 @@ func (e *endpoint) Read(buf []byte) (int, error) {
 		return 0, fmt.Errorf("usb: read: not an IN endpoint")
 	}
 
-	return e.transfer(buf, e.ReadTimeout)
+	return e.transfer(buf, e.readTimeout)
 }
 
 func (e *endpoint) Write(buf []byte) (int, error) {
@@ -47,33 +58,44 @@ func (e *endpoint) Write(buf []byte) (int, error) {
 		return 0, fmt.Errorf("usb: write: not an OUT endpoint")
 	}
 
-	return e.transfer(buf, e.WriteTimeout)
+	return e.transfer(buf, e.writeTimeout)
 }
 
 func (e *endpoint) Interface() InterfaceSetup { return e.InterfaceSetup }
 func (e *endpoint) Info() EndpointInfo        { return e.EndpointInfo }
 
+func (e *endpoint) newLibUSBTransfer(buf []byte, timeout time.Duration) (transferIntf, error) {
+	return newUSBTransfer(e.h, e.EndpointInfo, buf, timeout)
+}
+
 func (e *endpoint) transfer(buf []byte, timeout time.Duration) (int, error) {
 	if len(buf) == 0 {
 		return 0, nil
 	}
 
-	tt := e.TransferType()
-	t, err := newUSBTransfer((*deviceHandle)(e.Device.handle), e.EndpointInfo, buf, timeout)
+	t, err := e.newUSBTransfer(buf, timeout)
 	if err != nil {
 		return 0, err
 	}
 	defer t.free()
 
 	if err := t.submit(); err != nil {
-		log.Printf("bulk: %s failed to submit: %s", tt, err)
 		return 0, err
 	}
 
 	n, err := t.wait()
 	if err != nil {
-		log.Printf("bulk: %s failed: %s", tt, err)
-		return 0, err
+		return n, err
 	}
-	return n, err
+	return n, nil
+}
+
+func newEndpoint(d *Device) *endpoint {
+	ep := &endpoint{
+		h:            (*deviceHandle)(d.handle),
+		readTimeout:  d.ReadTimeout,
+		writeTimeout: d.WriteTimeout,
+	}
+	ep.newUSBTransfer = ep.newLibUSBTransfer
+	return ep
 }
diff --git a/usb/endpoint_info_test.go b/usb/endpoint_info_test.go
new file mode 100644
index 0000000..d19a323
--- /dev/null
+++ b/usb/endpoint_info_test.go
@@ -0,0 +1,46 @@
+// Copyright 2017 the gousb Authors.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package usb
+
+// IN bulk endpoint
+var testBulkInEP = EndpointInfo{
+	Address:       0x82,
+	Attributes:    uint8(TRANSFER_TYPE_BULK),
+	MaxPacketSize: 512,
+	PollInterval:  1,
+}
+
+var testBulkInSetup = InterfaceSetup{
+	Number:    0,
+	Alternate: 0,
+	IfClass:   uint8(CLASS_VENDOR_SPEC),
+	Endpoints: []EndpointInfo{testBulkInEP},
+}
+
+// OUT iso endpoint
+var testIsoOutEP = EndpointInfo{
+	Address:       0x06,
+	Attributes:    uint8(TRANSFER_TYPE_ISOCHRONOUS),
+	MaxPacketSize: 3<<11 + 1024,
+	MaxIsoPacket:  3 * 1024,
+	PollInterval:  1,
+}
+
+var testIsoOutSetup = InterfaceSetup{
+	Number:    0,
+	Alternate: 0,
+	IfClass:   uint8(CLASS_VENDOR_SPEC),
+	Endpoints: []EndpointInfo{testIsoOutEP},
+}
diff --git a/usb/endpoint_test.go b/usb/endpoint_test.go
new file mode 100644
index 0000000..eb05960
--- /dev/null
+++ b/usb/endpoint_test.go
@@ -0,0 +1,97 @@
+// Copyright 2017 the gousb Authors.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package usb
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+	"time"
+)
+
+type fakeTransfer struct {
+	buf []byte
+	ret int
+	err error
+}
+
+func (t *fakeTransfer) submit() error      { return nil }
+func (t *fakeTransfer) wait() (int, error) { return t.ret, t.err }
+func (t *fakeTransfer) free() error        { return nil }
+
+func TestEndpoint(t *testing.T) {
+	for _, epCfg := range []struct {
+		method string
+		InterfaceSetup
+		EndpointInfo
+	}{
+		{"Read", testBulkInSetup, testBulkInEP},
+		{"Write", testIsoOutSetup, testIsoOutEP},
+	} {
+		t.Run(epCfg.method, func(t *testing.T) {
+			for _, tc := range []struct {
+				buf     []byte
+				ret     int
+				err     error
+				want    int
+				wantErr bool
+			}{
+				{buf: nil, ret: 10, want: 0},
+				{buf: make([]byte, 128), ret: 60, want: 60},
+				{buf: make([]byte, 128), ret: 10, err: errors.New("some error"), want: 10, wantErr: true},
+			} {
+				ep := &endpoint{
+					InterfaceSetup: epCfg.InterfaceSetup,
+					EndpointInfo:   epCfg.EndpointInfo,
+					newUSBTransfer: func(buf []byte, timeout time.Duration) (transferIntf, error) {
+						return &fakeTransfer{buf: buf, ret: tc.ret, err: tc.err}, nil
+					},
+				}
+				op, ok := reflect.TypeOf(ep).MethodByName(epCfg.method)
+				if !ok {
+					t.Fatalf("method %s not found in endpoint struct", epCfg.method)
+				}
+				opv := op.Func.Interface().(func(*endpoint, []byte) (int, error))
+				got, err := opv(ep, tc.buf)
+				if (err != nil) != tc.wantErr {
+					t.Errorf("bulkInEP.Read(): got err: %v, err != nil is %v, want %v", err, err != nil, tc.wantErr)
+					continue
+				}
+				if got != tc.want {
+					t.Errorf("bulkInEP.Read(): got %d bytes, want %d", got, tc.want)
+				}
+			}
+		})
+	}
+}
+
+func TestEndpointWrongDirection(t *testing.T) {
+	ep := &endpoint{
+		InterfaceSetup: testBulkInSetup,
+		EndpointInfo:   testBulkInEP,
+	}
+	_, err := ep.Write([]byte{1, 2, 3})
+	if err == nil {
+		t.Error("bulkInEP.Write(): got nil error, want non-nil")
+	}
+	ep = &endpoint{
+		InterfaceSetup: testIsoOutSetup,
+		EndpointInfo:   testIsoOutEP,
+	}
+	_, err = ep.Read(make([]byte, 64))
+	if err == nil {
+		t.Error("isoOutEP.Read(): got nil error, want non-nil")
+	}
+}