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moby--moby/pkg/broadcastwriter/broadcastwriter_test.go
Andrew Gerrand 31cbf76d0c Use a slice instead of a map of io.WriteClosers in broadcastwriter
Maps rely on the keys being comparable.
Using an interface type as the map key is dangerous,
because some interface types are not comparable.
I talked about this in my "Stupid Gopher Tricks" talk:
	https://talks.golang.org/2015/tricks.slide

In this case, if the user-provided writer is backed by a slice
(such as io.MultiWriter) then the code will panic at run time.

Signed-off-by: Andrew Gerrand <adg@golang.org>
2015-08-21 14:08:04 +01:00

162 lines
3.6 KiB
Go

package broadcastwriter
import (
"bytes"
"errors"
"strings"
"testing"
)
type dummyWriter struct {
buffer bytes.Buffer
failOnWrite bool
}
func (dw *dummyWriter) Write(p []byte) (n int, err error) {
if dw.failOnWrite {
return 0, errors.New("Fake fail")
}
return dw.buffer.Write(p)
}
func (dw *dummyWriter) String() string {
return dw.buffer.String()
}
func (dw *dummyWriter) Close() error {
return nil
}
func TestBroadcastWriter(t *testing.T) {
writer := New()
// Test 1: Both bufferA and bufferB should contain "foo"
bufferA := &dummyWriter{}
writer.AddWriter(bufferA)
bufferB := &dummyWriter{}
writer.AddWriter(bufferB)
writer.Write([]byte("foo"))
if bufferA.String() != "foo" {
t.Errorf("Buffer contains %v", bufferA.String())
}
if bufferB.String() != "foo" {
t.Errorf("Buffer contains %v", bufferB.String())
}
// Test2: bufferA and bufferB should contain "foobar",
// while bufferC should only contain "bar"
bufferC := &dummyWriter{}
writer.AddWriter(bufferC)
writer.Write([]byte("bar"))
if bufferA.String() != "foobar" {
t.Errorf("Buffer contains %v", bufferA.String())
}
if bufferB.String() != "foobar" {
t.Errorf("Buffer contains %v", bufferB.String())
}
if bufferC.String() != "bar" {
t.Errorf("Buffer contains %v", bufferC.String())
}
// Test3: Test eviction on failure
bufferA.failOnWrite = true
writer.Write([]byte("fail"))
if bufferA.String() != "foobar" {
t.Errorf("Buffer contains %v", bufferA.String())
}
if bufferC.String() != "barfail" {
t.Errorf("Buffer contains %v", bufferC.String())
}
// Even though we reset the flag, no more writes should go in there
bufferA.failOnWrite = false
writer.Write([]byte("test"))
if bufferA.String() != "foobar" {
t.Errorf("Buffer contains %v", bufferA.String())
}
if bufferC.String() != "barfailtest" {
t.Errorf("Buffer contains %v", bufferC.String())
}
// Test4: Test eviction on multiple simultaneous failures
bufferB.failOnWrite = true
bufferC.failOnWrite = true
bufferD := &dummyWriter{}
writer.AddWriter(bufferD)
writer.Write([]byte("yo"))
writer.Write([]byte("ink"))
if strings.Contains(bufferB.String(), "yoink") {
t.Errorf("bufferB received write. contents: %q", bufferB)
}
if strings.Contains(bufferC.String(), "yoink") {
t.Errorf("bufferC received write. contents: %q", bufferC)
}
if g, w := bufferD.String(), "yoink"; g != w {
t.Errorf("bufferD = %q, want %q", g, w)
}
writer.Clean()
}
type devNullCloser int
func (d devNullCloser) Close() error {
return nil
}
func (d devNullCloser) Write(buf []byte) (int, error) {
return len(buf), nil
}
// This test checks for races. It is only useful when run with the race detector.
func TestRaceBroadcastWriter(t *testing.T) {
writer := New()
c := make(chan bool)
go func() {
writer.AddWriter(devNullCloser(0))
c <- true
}()
writer.Write([]byte("hello"))
<-c
}
func BenchmarkBroadcastWriter(b *testing.B) {
writer := New()
setUpWriter := func() {
for i := 0; i < 100; i++ {
writer.AddWriter(devNullCloser(0))
writer.AddWriter(devNullCloser(0))
writer.AddWriter(devNullCloser(0))
}
}
testLine := "Line that thinks that it is log line from docker"
var buf bytes.Buffer
for i := 0; i < 100; i++ {
buf.Write([]byte(testLine + "\n"))
}
// line without eol
buf.Write([]byte(testLine))
testText := buf.Bytes()
b.SetBytes(int64(5 * len(testText)))
b.ResetTimer()
for i := 0; i < b.N; i++ {
b.StopTimer()
setUpWriter()
b.StartTimer()
for j := 0; j < 5; j++ {
if _, err := writer.Write(testText); err != nil {
b.Fatal(err)
}
}
b.StopTimer()
writer.Clean()
b.StartTimer()
}
}