关于UI Automation框架

微软提供的UI Automation框架给开发windows平台的自动化测试带来了很大的便利，这里就总结一下相关的代码。

首先，直接使用UI Automation框架，完成一个NotePad的about窗口中的 “OK” button的点击：

 AutomationElement root = AutomationElement.RootElement;
 AutomationElement about_notepad_windows = root.FindFirst(
     TreeScope.Descendants,
     new AndCondition(
         new PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.Window),
         new PropertyCondition(AutomationElement.NameProperty, "About Notepad")));
 if (about_notepad_windows == null)
 {
     Console.WriteLine("About Notepad window doesn't exist!!");
     return;
 }

 AutomationElement ok_button = about_notepad_windows.FindFirst(
     TreeScope.Children,
     new AndCondition(
         new PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.Button),
         new PropertyCondition(AutomationElement.NameProperty, "OK")));
 Object invokePatternObject;
 if (ok_button.TryGetCurrentPattern(InvokePattern.Pattern, out invokePatternObject))
 {
     (invokePatternObject as InvokePattern).Invoke();
 }

好吧，上面是面向过程的代码，不利于复用，那么让我们来将其抽象成类，

首先定义一个基类UIAControl，它包含有搜索的根节点searchRoot，搜索范围searchScope和条件searchConditions，使用这三个对象来搜索一个AutomationElement对象并将其赋给innerElement，由于默认使用的是AndCondition来关联所有传入的condition对象，所以将CombineCondition方法设为虚方法，以便如果有子类想要使用其他关联条件处理condition的时候可以覆盖：

 public abstract class UIAControl
 {
     private UIAControl searchRoot;
     private TreeScope searchScope;
     private List<Condition> searchConditions;

     protected void AddSearchCondition(Condition condition)
     {
         this.searchConditions.Add(condition);
     }

     public UIAControl()
     {
         searchConditions = new List<Condition>();
         searchScope = TreeScope.Descendants;
     }

     public UIAControl(UIAControl searchRoot)
         : this()
     {
         this.searchRoot = searchRoot;
     }

     public UIAControl(IntPtr hwnd)
         : this()
     {
         searchConditions.Add(PropertyConditionFactory.GetHandleCondition(hwnd));
     }

     public AutomationElement.AutomationElementInformation? ControlInformation
     {
         get
         {
             if (Exists())
             {
                 return InnerElement.Current;
             }
             return null;
         }
     }

     private AutomationElement innerElement;
     public AutomationElement InnerElement
     {
         get
         {
             if (innerElement == null)
             {
                 innerElement = SearchElement();
             }
             return innerElement;
         }
     }

     protected virtual AutomationElement SearchElement()
     {
         AutomationElement ele = null;
         if (searchRoot == null)
         {
             ele = AutomationElement.RootElement;
         }
         else
         {
             ele = searchRoot.InnerElement;
         }

         if (ele == null ||  == searchConditions.Count)
         {
             return ele;
         }
         else
         {
             Condition conditions = CombineAllConditions();
             try
             {
                 return ele.FindFirst(searchScope, conditions);
             }
             catch(Exception ex)
             {
                 Console.WriteLine("Getting exception when searching element: " + ex.Message);
                 return null;
             }
         }
     }

     //Can override this method to return other type conditions, default will return AndCondition
     protected virtual Condition CombineAllConditions()
     {
         if (searchConditions.Count > )
         {
             return new AndCondition(searchConditions.ToArray());
         }
         else if (searchConditions.Count == )
         {
             return searchConditions.First();
         }
         else
         {
             return null;
         }

     }

     public virtual bool Exists()
     {
         //Before checking existence, set innerElement to null to trigger fresh search.
         return null != SearchElement();
     }

     public bool WaitTillExist(int timeout, int interval = )
     {
         Stopwatch stopwatch = new Stopwatch();
         stopwatch.Start();
         while (stopwatch.ElapsedMilliseconds < timeout)
         {
             if (this.Exists())
             {
                 return true;
             }

             Thread.Sleep(interval);
         }

         return false;
     }

     protected bool CallPattern<T>(T pattern, Action<T> action) where T : BasePattern
     {
         if (pattern != null)
         {
             try
             {
                 action(pattern);
                 return true;
             }
             catch (Exception ex)
             {
                 Console.WriteLine(ex.Message);
             }
         }
         return false;
     }

     protected T GetPattern<T>() where T : BasePattern
     {
         var ele = InnerElement;
         if (ele != null)
         {
             try
             {
                 var patternIdentifier = (AutomationPattern)(typeof(T).GetField("Pattern").GetValue(null));
                 return ele.GetCurrentPattern(patternIdentifier) as T;
             }
             catch (Exception ex)
             {
                 Console.WriteLine(ex.Message);
             }
         }
         return null;
     }

     public bool Invoke()
     {
         return CallPattern(GetPattern<InvokePattern>(), (pattern) => pattern.Invoke());
     }
 }

之后，就可以定义其他控件类型了，下面定义了一个button的对象，只有一个click方法：

     public class UIAButton : UIAControl
     {
         public UIAButton(UIAControl root, string name)
             : base(root)
         {
             AddSearchCondition(PropertyConditionFactory.GetNameCondition(name));
             AddSearchCondition(PropertyConditionFactory.GetControlTypeCondition(ControlType.Button));
         }

         public void Click()
         {
             this.Invoke();
         }
     }

再定义一个window对象：

     public class UIAWindow : UIAControl
     {
         public UIAWindow(string name)
         {
             AddSearchCondition(PropertyConditionFactory.GetNameCondition(name));
             AddSearchCondition(PropertyConditionFactory.GetControlTypeCondition(ControlType.Window));
         }

         public bool Close()
         {
             return CallPattern(GetPattern<WindowPattern>(), (pattern) => pattern.Close());
         }

         public bool Maximize()
         {
             return CallPattern(GetPattern<WindowPattern>(), (pattern) => pattern.SetWindowVisualState(WindowVisualState.Maximized));
         }

         public bool Minimize()
         {
             return CallPattern(GetPattern<WindowPattern>(), (pattern) => pattern.SetWindowVisualState(WindowVisualState.Minimized));
         }

         public bool Resize(int width, int height)
         {
             return CallPattern(GetPattern<TransformPattern>(), (pattern) => pattern.Resize(width, height));
         }
     }

最后，使用上面两个控件类型来完成Ok按钮的点击：

 UIAWindow windows = new UIAWindow("About Notepad");
 UIAButton ok_button = new UIAButton(windows, "OK");
 if (windows.WaitTillExist())
 {
     ok_button.Click();
 }

当然，如果是稍微上点规模的项目，就需要利用这些控件抽象出一个对应产品功能的produc类了。

如果不想从头写起的话，可以看看开源工具White， 一个优秀的基于UI Automation的测试框架。