lib/os: copy lib/io#ConfirmYesNo to lib/os

The lib/io package will be deprecated in the future.

2 files changed, 117 insertions, 0 deletions

diff --git a/lib/os/os.go b/lib/os/os.go
index ed2c197e..53999775 100644
--- a/lib/os/os.go
+++ b/lib/os/os.go
@@ -7,6 +7,7 @@
 package os
 
 import (
+	"bufio"
 	"fmt"
 	"io"
 	"log"
@@ -16,6 +17,59 @@ import (
 	"github.com/shuLhan/share/lib/ascii"
 )
 
+// ConfirmYesNo display a question to standard output and read for answer
+// from input Reader for simple yes "y" or no "n" answer.
+// If input Reader is nil, it will set to standard input.
+// If "defIsYes" is true and answer is empty (only new line), then it will
+// return true.
+func ConfirmYesNo(in io.Reader, msg string, defIsYes bool) bool {
+	var (
+		r         *bufio.Reader
+		b, answer byte
+		err       error
+	)
+
+	if in == nil {
+		r = bufio.NewReader(os.Stdin)
+	} else {
+		r = bufio.NewReader(in)
+	}
+
+	yon := "[y/N]"
+
+	if defIsYes {
+		yon = "[Y/n]"
+	}
+
+	fmt.Printf("%s %s ", msg, yon)
+
+	for {
+		b, err = r.ReadByte()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			break
+		}
+		if b == ' ' || b == '\t' {
+			continue
+		}
+		if b == '\n' {
+			break
+		}
+		if answer == 0 {
+			answer = b
+		}
+	}
+
+	if answer == 'y' || answer == 'Y' {
+		return true
+	}
+	if answer == 0 {
+		return defIsYes
+	}
+
+	return false
+}
+
 // Copy file from in to out.
 // If the output file is already exist, it will be truncated.
 // If the file is not exist, it will created with permission set to user's
diff --git a/lib/os/os_test.go b/lib/os/os_test.go
index 2d0d7a3f..aa5337a2 100644
--- a/lib/os/os_test.go
+++ b/lib/os/os_test.go
@@ -5,8 +5,71 @@ import (
 	"testing"
 
 	"github.com/shuLhan/share/lib/test"
+	"github.com/shuLhan/share/lib/test/mock"
 )
 
+func TestConfirmYesNo(t *testing.T) {
+	cases := []struct {
+		answer   string
+		defIsYes bool
+		exp      bool
+	}{{
+		defIsYes: true,
+		exp:      true,
+	}, {
+		defIsYes: true,
+		answer:   `  `,
+		exp:      true,
+	}, {
+		defIsYes: true,
+		answer:   `  no`,
+		exp:      false,
+	}, {
+		defIsYes: true,
+		answer:   ` yes`,
+		exp:      true,
+	}, {
+		defIsYes: true,
+		answer:   ` Ys`,
+		exp:      true,
+	}, {
+		defIsYes: false,
+		exp:      false,
+	}, {
+		defIsYes: false,
+		answer:   ``,
+		exp:      false,
+	}, {
+
+		defIsYes: false,
+		answer:   `  no`,
+		exp:      false,
+	}, {
+		defIsYes: false,
+		answer:   `  yes`,
+		exp:      true,
+	}}
+
+	in := mock.Stdin()
+
+	for _, c := range cases {
+		t.Log(c)
+
+		_, err := in.WriteString(c.answer + "\n")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		mock.ResetStdin(false)
+
+		got := ConfirmYesNo(in, `confirm`, c.defIsYes)
+
+		test.Assert(t, `answer`, c.exp, got)
+
+		mock.ResetStdin(true)
+	}
+}
+
 func TestCopy(t *testing.T) {
 	cases := []struct {
 		desc   string