Allow caller to await and evaluate command completion (addresses leem…

…cloughlin#1)

expect.go

@@ -31,6 +31,9 @@ line is:
 	}
 	exp.Send(EOF)
 
+        result, err := return exp.Wait()
+        fmt.Println("Command result:", result, err)
+
 This package has only been tested on Linux
 */
 package expect
@@ -114,19 +117,11 @@ type Expect struct {
 	// On EOF being read from Cmd this is set (and ExpectReader is ended)
 	Eof bool
 
-	// Result is filled in asynchronously after the cmd exits
-	Result ExpectWaitResult
-
 	// Cancellation context: @cancel causes internal and os/exec cancellation
 	ctx    context.Context
 	cancel context.CancelFunc
 }
 
-type ExpectWaitResult struct {
-	ProcessState *os.ProcessState
-	Error        error
-}
-
 // debugf logs only if Debug is true
 func debugf(format string, args ...interface{}) {
 	if Debug {
@@ -167,7 +162,6 @@ func NewExpectContext(parentCtx context.Context, prog string, arg ...string) (ex
 	if exp.File, err = pty.Start(exp.cmd); err != nil {
 		return nil, err
 	}
-	go exp.expectReaper()
 
 	// make the pty non blocking so when I read from it I dont jam up
 	if err = syscall.SetNonblock(int(exp.File.Fd()), true); err != nil {
@@ -181,10 +175,11 @@ func NewExpectContext(parentCtx context.Context, prog string, arg ...string) (ex
 	return exp, nil
 }
 
-// expectReaper reaps the process if it ends for any reason and saves the
-// Wait() result
-func (exp *Expect) expectReaper() {
-	exp.Result.ProcessState, exp.Result.Error = exp.cmd.Process.Wait()
+// Wait() reaps the command process and returns its resulting process state.
+// If the command terminated due to context cancellation, error will be one of
+// the package constants context.Canceled or context.Deadline.
+func (exp *Expect) Wait() (*os.ProcessState, error) {
+	return exp.cmd.Process.Wait()
 }
 
 // SetCmdOut if a non-nil io.Writer is passed it will be sent a copy of everything

expect_test.go

@@ -82,27 +82,13 @@ func checkResultRe(t *testing.T, pat string, re *regexp.Regexp, i int, n int, fo
 	}
 }
 
+// showWaitResults awaits command completion, and prints the resulting process state
 func showWaitResult(t *testing.T, exp *Expect) {
-	// Wait a little bit for Result to be filled in
-	time.Sleep(time.Millisecond * 10)
-	// Try a few fimes to see if its valid (maybe I should have used a channel
-	// but checking for all the errors is painful for code I expect to be used
-	// so rarely)
-	for i := 1; i <= 3; i++ {
-		if exp.Result.ProcessState != nil {
-			break
-		}
-		t.Logf("pause %d for Wait() result", i)
-		time.Sleep(time.Second)
-	}
-	if exp.Result.ProcessState == nil {
-		t.Logf("Wait() result never went valid")
-		return
-	}
-	if exp.Result.Error != nil {
-		t.Logf("Wait() result: %s, %s", exp.Result.ProcessState, exp.Result.Error)
+	processState, err := exp.Wait()
+	if err != nil {
+		t.Logf("Wait() error result: %s, %s", processState, err)
 	} else {
-		t.Logf("Wait() result: %s", exp.Result.ProcessState)
+		t.Logf("Wait() result: %s", processState)
 	}
 }