integration-cli: remove timeout dependency on TestEventsUntag

TestEventsUntag requires a `timeout` command which does not
exist on OS X or Windows (in fact, windows has a totally different
timeout program and this test was accidentally using it).

- Created runCommandWithOutputForDuration.
  This entirely replaces runDockerCommandWithTimeout and
  removes dependency to `timeout` command.
- Made runDockerCommandWithTimeout reuse runDockerCommandForDuration.

TestEventsUntag works now on Windows.

Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>

integration-cli/utils.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math/rand"
@@ -63,27 +64,49 @@ func runCommandWithStdoutStderr(cmd *exec.Cmd) (stdout string, stderr string, ex
 	return
 }
 
+func runCommandWithOutputForDuration(cmd *exec.Cmd, duration time.Duration) (output string, exitCode int, timedOut bool, err error) {
+	var outputBuffer bytes.Buffer
+	if cmd.Stdout != nil {
+		err = errors.New("cmd.Stdout already set")
+		return
+	}
+	cmd.Stdout = &outputBuffer
+
+	if cmd.Stderr != nil {
+		err = errors.New("cmd.Stderr already set")
+		return
+	}
+	cmd.Stderr = &outputBuffer
+
+	done := make(chan error)
+	go func() {
+		exitErr := cmd.Run()
+		exitCode = processExitCode(exitErr)
+		done <- exitErr
+	}()
+
+	select {
+	case <-time.After(duration):
+		killErr := cmd.Process.Kill()
+		if killErr != nil {
+			fmt.Printf("failed to kill (pid=%d): %v\n", cmd.Process.Pid, killErr)
+		}
+		timedOut = true
+		break
+	case err = <-done:
+		break
+	}
+	output = outputBuffer.String()
+	return
+}
+
 var ErrCmdTimeout = fmt.Errorf("command timed out")
 
 func runCommandWithOutputAndTimeout(cmd *exec.Cmd, timeout time.Duration) (output string, exitCode int, err error) {
-	done := make(chan error)
-	go func() {
-		output, exitCode, err = runCommandWithOutput(cmd)
-		if err != nil || exitCode != 0 {
-			done <- fmt.Errorf("failed to run command: %s", err)
-			return
-		}
-		done <- nil
-	}()
-	select {
-	case <-time.After(timeout):
-		killFailed := cmd.Process.Kill()
-		if killFailed == nil {
-			fmt.Printf("failed to kill (pid=%d): %v\n", cmd.Process.Pid, err)
-		}
+	var timedOut bool
+	output, exitCode, timedOut, err = runCommandWithOutputForDuration(cmd, timeout)
+	if timedOut {
 		err = ErrCmdTimeout
-	case <-done:
-		break
 	}
 	return
 }