From c76427858ad8c431c90b5ea9909dc1e4632a426c Mon Sep 17 00:00:00 2001
From: Chris Koch <chrisko@google.com>
Date: Sat, 25 Feb 2023 22:38:49 -0800
Subject: ElapsedTime: tests for FromBytes, ToBytes, and Getter

Signed-off-by: Chris Koch <chrisko@google.com>
---
 dhcpv6/option_elapsedtime_test.go | 83 +++++++++++++++++++++++++++------------
 1 file changed, 57 insertions(+), 26 deletions(-)

diff --git a/dhcpv6/option_elapsedtime_test.go b/dhcpv6/option_elapsedtime_test.go
index b0d2dc1..5e95cda 100644
--- a/dhcpv6/option_elapsedtime_test.go
+++ b/dhcpv6/option_elapsedtime_test.go
@@ -1,29 +1,69 @@
 package dhcpv6
 
 import (
-	"bytes"
+	"errors"
+	"fmt"
+	"reflect"
 	"testing"
 	"time"
 
-	"github.com/stretchr/testify/require"
+	"github.com/google/go-cmp/cmp"
+	"github.com/u-root/uio/uio"
 )
 
-func TestOptElapsedTime(t *testing.T) {
-	var opt optElapsedTime
-	err := opt.FromBytes([]byte{0xaa, 0xbb})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if elapsedTime := opt.ElapsedTime; elapsedTime != 0xaabb*10*time.Millisecond {
-		t.Fatalf("Invalid elapsed time. Expected 0xaabb, got %v", elapsedTime)
-	}
-}
+func TestElapsedTimeParseAndGetter(t *testing.T) {
+	for i, tt := range []struct {
+		buf  []byte
+		err  error
+		want time.Duration
+	}{
+		{
+			buf: []byte{
+				0, 8, // Elapsed Time option
+				0, 2, // length
+				0, 2,
+			},
+			want: 20 * time.Millisecond,
+		},
+		{
+			buf: []byte{
+				0, 8, // Elapsed Time option
+				0, 1, // length
+				0,
+			},
+			err: uio.ErrBufferTooShort,
+		},
+		{
+			buf: []byte{
+				0, 8, // Elapsed Time option
+				0, 3, // length
+				0, 2, 2,
+			},
+			err: uio.ErrUnreadBytes,
+		},
+		{
+			buf: []byte{0, 8, 0},
+			err: uio.ErrUnreadBytes,
+		},
+	} {
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			var mo MessageOptions
+			if err := mo.FromBytes(tt.buf); !errors.Is(err, tt.err) {
+				t.Errorf("FromBytes = %v, want %v", err, tt.err)
+			}
+			if got := mo.ElapsedTime(); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("ElapsedTime = %v, want %v", got, tt.want)
+			}
 
-func TestOptElapsedTimeToBytes(t *testing.T) {
-	opt := OptElapsedTime(0)
-	expected := []byte{0, 0}
-	if toBytes := opt.ToBytes(); !bytes.Equal(expected, toBytes) {
-		t.Fatalf("Invalid ToBytes output. Expected %v, got %v", expected, toBytes)
+			if tt.err == nil {
+				var m MessageOptions
+				m.Add(OptElapsedTime(tt.want))
+				got := m.ToBytes()
+				if diff := cmp.Diff(tt.buf, got); diff != "" {
+					t.Errorf("ToBytes mismatch (-want, +got): %s", diff)
+				}
+			}
+		})
 	}
 }
 
@@ -34,12 +74,3 @@ func TestOptElapsedTimeString(t *testing.T) {
 		t.Fatalf("Invalid elapsed time string. Expected %v, got %v", expected, optString)
 	}
 }
-
-func TestOptElapsedTimeParseInvalidOption(t *testing.T) {
-	var opt optElapsedTime
-	err := opt.FromBytes([]byte{0xaa})
-	require.Error(t, err, "A short option should return an error")
-
-	err = opt.FromBytes([]byte{0xaa, 0xbb, 0xcc})
-	require.Error(t, err, "An option with too many bytes should return an error")
-}
-- 
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