Add pty specific repro of superfluous output

test/pty/go.mod

@@ -0,0 +1,9 @@
+module github.com/ActiveState/termtest/test/pty
+
+go 1.20
+
+require github.com/creack/pty v0.0.0-00010101000000-000000000000
+
+require golang.org/x/sys v0.0.0-20220721230656-c6bc011c0c49 // indirect
+
+replace github.com/creack/pty => github.com/photostorm/pty v0.0.0-20230324012736-6794a5ba0ba0

test/pty/go.sum

@@ -0,0 +1,4 @@
+github.com/photostorm/pty v0.0.0-20230324012736-6794a5ba0ba0 h1:12sw4rIcXrMHdMlCbTmaC3RkBfHR8zdoAsetnmMWRh0=
+github.com/photostorm/pty v0.0.0-20230324012736-6794a5ba0ba0/go.mod h1:KO+FcPtyLAiRC0hJwreJVvfwc7vnNz77UxBTIGHdPVk=
+golang.org/x/sys v0.0.0-20220721230656-c6bc011c0c49 h1:TMjZDarEwf621XDryfitp/8awEhiZNiwgphKlTMGRIg=
+golang.org/x/sys v0.0.0-20220721230656-c6bc011c0c49/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

test/pty/helloworld.go

@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello")
+}

test/pty/pty_test.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/creack/pty"
+)
+
+func Test_Pty_Output(t *testing.T) {
+	_, filename, _, ok := runtime.Caller(0)
+	if !ok {
+		t.Fatal("unable to get the current filename")
+	}
+	c := exec.Command("go", "run", filepath.Join(filepath.Dir(filename), "helloworld.go"))
+
+	ptyrw, err := pty.StartWithSize(c, &pty.Winsize{Cols: 140, Rows: 10})
+	if err != nil {
+		t.Fatalf("pty could not start: %s", err)
+	}
+	defer func() { _ = ptyrw.Close() }()
+
+	var output []byte
+	for {
+		snapshot := make([]byte, 1024)
+		n, err := ptyrw.Read(snapshot)
+		if n > 0 {
+			fmt.Printf("Read: %s", snapshot[:n])
+			output = append(output, snapshot[:n]...)
+		}
+		if err != nil {
+			t.Fatalf("read error: %s", err)
+			break
+		}
+		time.Sleep(time.Millisecond * 100)
+	}
+	outputv := strings.TrimSpace(string(output))
+	if outputv != "hello" {
+		t.Fatalf("Output is not 'hello', got: %s", outputv)
+	}
+}