TestPropertyDrawer

using UnityEngine;
using UnityEditor;
using System.Collections;

[CustomPropertyDrawer(typeof(Test))]
public class TestPropertyDrawer : PropertyDrawer {

    float lineHeight = 16;
    float lineMargin = 2;

    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        EditorGUI.BeginProperty(position, label, property);
        SerializedProperty PropTestInt = property.FindPropertyRelative("testInt");
        PropTestInt.intValue = EditorGUI.IntField(new Rect(position.x, position.y + lineHeight, position.width, lineHeight), PropTestInt.intValue);
        EditorGUI.EndProperty();
    }

    public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
    {
        return lineHeight;
    }
}