fix tests

2 files changed, 15 insertions, 2 deletions

diff --git a/logger/logger.go b/logger/logger.go
index bb4588f1ed..cc2421ad06 100644
--- a/logger/logger.go
+++ b/logger/logger.go
@@ -106,12 +106,14 @@ type ConsoleLog struct {
	sys *log.Logger
 }
 
+var osStderr = os.Stderr
+
 // Debug sends the msg to syslog
 func (l *ConsoleLog) Debug(msg string) {
	s := "DEBUG: " + msg
	l.sys.Output(3, s)
	// show debug log when run manually
-	if osutil.Isatty(int(os.Stderr.Fd())) {
+	if osutil.Isatty(int(osStderr.Fd())) {
	l.log.Output(3, s)
	}
 }
diff --git a/logger/logger_test.go b/logger/logger_test.go
index a3a98ff156..570fb26205 100644
--- a/logger/logger_test.go
+++ b/logger/logger_test.go
@@ -22,7 +22,9 @@ package logger
 import (
	"bytes"
	"fmt"
+	"io/ioutil"
	"log"
+	"os"
	"testing"
 
	. "gopkg.in/check.v1"
@@ -74,11 +76,20 @@ func (s *LogSuite) TestNew(c *C) {
	c.Check(l.log, NotNil)
 }
 
-func (s *LogSuite) TestDebugf(c *C) {
+func (s *LogSuite) TestDebugfForNonTTY(c *C) {
	var logbuf bytes.Buffer
	l, err := NewConsoleLog(&logbuf, DefaultFlags)
	c.Assert(err, IsNil)
 
+	// stderr is not a tty for this test
+	tmpf, err := ioutil.TempFile("", "debugf")
+	c.Assert(err, IsNil)
+	osStderr = tmpf
+	defer func() {
+	os.Remove(tmpf.Name())
+	osStderr = os.Stderr
+	}()
+
	SetLogger(l)
 
	Debugf("xyzzy")