如何在Android或Android Espresso中获取视图层次结构

Question

我正在使用Android Espresso，当它找不到匹配项时，会抛出异常并打印视图层次结构。在运行Android测试或Espresso时，有没有一种动态获取此类视图层次结构的方法？

View Hierarchy:
+>DecorView{id=-1, visibility=VISIBLE, width=480, height=800,     has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=2}
|
+->LinearLayout{id=-1, visibility=VISIBLE, width=480, height=800, has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=2}
|
+-->ViewStub{id=16909225, res-name=action_mode_bar_stub, visibility=GONE, width=0, height=0, has-focus=false, has-focusable=false, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=true, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0}
|
+-->FrameLayout{id=-1, visibility=VISIBLE, width=480, height=764, has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=36.0, child-count=1}
|
+--->ActionBarOverlayLayout{id=2131427395, res-name=decor_content_parent, visibility=VISIBLE, width=480, height=764, has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=2}
| 

- Pezh

Answer 1

您可以引发异常，这样将会出现视图层次结构。例如，将以下内容放置在您的测试文件中：

onView(withText("XYZ")).perform(click())

由于文本XYZ不存在，结果将是：

...espresso.NoMatchingViewException: No views in hierarchy found matching: with text: is "XYZ"

View Hierarchy:
+>DecorView{id=-1, visibility=VISIBLE, width=1024, height=600, has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=1}
|
+->LinearLayout{id=-1, visibility=VISIBLE, width=1024, height=600, has-focus=true, has-focusable=true, has-window-focus=true, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=2}
|
...

- ivan.panasiuk

Answer 2

给定的Android View hierarchy是一种树形结构，使用某些算法遍历每个树节点更加容易，您可以在https://developer.android.com/reference/android/support/test/espresso/util/TreeIterables.html中查看这些方法。

它打印异常跟踪的方式使用了一种称为breadthFirstViewTraversal的方法，并在ViewFinderImpl类中打印出视图树https://developer.android.com/reference/android/support/test/espresso/base/ViewFinderImpl.html。

- WenChao

---

我可以问一个额外的问题，如何获取当前活动以获取根视图并将其传递给函数？ - Pezh

Answer 3

HumanReadables.getViewHierarchyErrorMessage是Espresso在视图匹配失败时用于打印图形的函数，因此不需要抛出虚假的匹配并捕获它，只需：

\\ import androidx.test.espresso.util.HumanReadables
val theRootView = fragment.view
val viewHierarchy: String = HumanReadables.getViewHierarchyErrorMessage(theRootView, null, "", null)

你需要传递一个视图。例如，如果你正在使用一个Fragment，fragment.view将是图形的根。

- Matthew Fisher

---

你能否专门编辑你的答案，添加更多细节并解释为什么你的答案可以解决这个问题？ - Elikill58