add more tests

core/iox/pipe.go

@@ -0,0 +1,23 @@
+package iox
+
+import "os"
+
+// RedirectInOut redirects stdin to r, stdout to w, and callers need to call restore afterwards.
+func RedirectInOut() (restore func(), err error) {
+	var r, w *os.File
+	r, w, err = os.Pipe()
+	if err != nil {
+		return
+	}
+
+	ow := os.Stdout
+	os.Stdout = w
+	or := os.Stdin
+	os.Stdin = r
+	restore = func() {
+		os.Stdin = or
+		os.Stdout = ow
+	}
+
+	return
+}

core/iox/pipe_test.go

@@ -0,0 +1,13 @@
+package iox
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRedirectInOut(t *testing.T) {
+	restore, err := RedirectInOut()
+	assert.Nil(t, err)
+	defer restore()
+}