linkerd2/testutil/stream.go at ver/rautz · jojinkb/linkerd2

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package testutil

import (

"bufio"

"fmt"

"io"

"os/exec"

"strings"

"time"

)

// Stream provides the ability of read the output of an executing process while

// it is still running

type Stream struct {

cmd *exec.Cmd

out io.ReadCloser

}

// Stop closes the stream and kills the process

func (s *Stream) Stop() {

s.out.Close()

s.cmd.Process.Kill()

}

// ReadUntil reads from the process output until specified number of lines has

// been reached, or until a timeout

func (s *Stream) ReadUntil(lineCount int, timeout time.Duration) ([]string, error) {

output := make([]string, 0)

lines := make(chan string)

timeoutAfter := time.NewTimer(timeout)

defer timeoutAfter.Stop()

scanner := bufio.NewScanner(s.out)

stopSignal := false

go func() {

for scanner.Scan() {

lines <- scanner.Text()

if stopSignal {

close(lines)

return

}

}()

for {

select {

case <-timeoutAfter.C:

stopSignal = true

return output, fmt.Errorf("cmd [%s] Timed out trying to read %d lines", strings.Join(s.cmd.Args, " "), lineCount)

case line := <-lines:

output = append(output, line)

if len(output) >= lineCount {

stopSignal = true

return output, nil

}

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