Fix crash when attempting to focus when no items are visible.

Judging from stack, monkey test is somehow getting into a state
where no items are currently visible. Safeguard this edge case
from crashing.

Test: docsui unittest
Change-Id: I10dee1dfd8373012f4a1bedcbda851653c12f5ee
Fixes: 64589752

4 files changed, 71 insertions, 2 deletions

diff --git a/src/com/android/documentsui/FocusManager.java b/src/com/android/documentsui/FocusManager.java
index 8f3795cad..097516e56 100644
--- a/src/com/android/documentsui/FocusManager.java
+++ b/src/com/android/documentsui/FocusManager.java
@@ -153,6 +153,10 @@ public final class FocusManager implements FocusHandler {
         final int focusPos = (mScope.lastFocusPosition != RecyclerView.NO_POSITION)
                 ? mScope.lastFocusPosition
                 : mScope.layout.findFirstVisibleItemPosition();
+        if (focusPos == RecyclerView.NO_POSITION) {
+            return false;
+        }
+
         focusItem(focusPos);
         return true;
     }
diff --git a/tests/common/com/android/documentsui/testing/TestGridLayoutManager.java b/tests/common/com/android/documentsui/testing/TestGridLayoutManager.java
new file mode 100644
index 000000000..f883e5e58
--- /dev/null
+++ b/tests/common/com/android/documentsui/testing/TestGridLayoutManager.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.documentsui.testing;
+
+import android.content.Context;
+import android.support.v7.widget.GridLayoutManager;
+
+import org.mockito.Mockito;
+
+public class TestGridLayoutManager extends GridLayoutManager {
+
+    private int mFirstVisibleItemPosition;
+
+    public static TestGridLayoutManager create() {
+        final TestGridLayoutManager manager = Mockito.mock(TestGridLayoutManager.class,
+                Mockito.withSettings().defaultAnswer(Mockito.CALLS_REAL_METHODS));
+        return manager;
+    }
+
+    @Override
+    public int findFirstVisibleItemPosition() { return mFirstVisibleItemPosition; }
+
+    public void setFirstVisibleItemPosition(int position) { mFirstVisibleItemPosition = position; }
+
+    private TestGridLayoutManager(Context context, int spanCount) {
+        super(context, spanCount);
+    }
+}
diff --git a/tests/common/com/android/documentsui/testing/TestRecyclerView.java b/tests/common/com/android/documentsui/testing/TestRecyclerView.java
index 8759a9a21..a1f8e7f26 100644
--- a/tests/common/com/android/documentsui/testing/TestRecyclerView.java
+++ b/tests/common/com/android/documentsui/testing/TestRecyclerView.java
@@ -17,6 +17,7 @@
 package com.android.documentsui.testing;
 
 import android.content.Context;
+import android.support.test.InstrumentationRegistry;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 
@@ -32,6 +33,7 @@ public class TestRecyclerView extends RecyclerView {
 
     private List<RecyclerView.ViewHolder> holders = new ArrayList<>();
     private TestDocumentsAdapter adapter;
+    private RecyclerView.LayoutManager mLayoutManager;
 
     public TestRecyclerView(Context context) {
         super(context);
@@ -55,6 +57,16 @@ public class TestRecyclerView extends RecyclerView {
         return adapter;
     }
 
+    @Override
+    public void setLayoutManager(LayoutManager manager) {
+        mLayoutManager = manager;
+    }
+
+    @Override
+    public RecyclerView.LayoutManager getLayoutManager() {
+        return mLayoutManager;
+    }
+
     public void setItems(List<String> modelIds) {
         holders = new ArrayList<>();
         for (String modelId: modelIds) {
@@ -64,8 +76,8 @@ public class TestRecyclerView extends RecyclerView {
     }
 
     public static TestRecyclerView create(List<String> modelIds) {
-        final TestRecyclerView view = Mockito.mock(TestRecyclerView.class,
-                Mockito.withSettings().defaultAnswer(Mockito.CALLS_REAL_METHODS));
+        final TestRecyclerView view =
+                new TestRecyclerView(InstrumentationRegistry.getTargetContext());
         view.holders = new ArrayList<>();
         for (String modelId: modelIds) {
             view.holders.add(new TestViewHolder(Views.createTestView()));
diff --git a/tests/unit/com/android/documentsui/FocusManagerTest.java b/tests/unit/com/android/documentsui/FocusManagerTest.java
index cd71db6cd..b386f82b3 100644
--- a/tests/unit/com/android/documentsui/FocusManagerTest.java
+++ b/tests/unit/com/android/documentsui/FocusManagerTest.java
@@ -16,6 +16,7 @@
 
 package com.android.documentsui;
 
+import android.support.v7.widget.RecyclerView;
 import android.test.AndroidTestCase;
 import android.test.suitebuilder.annotation.SmallTest;
 
@@ -25,6 +26,7 @@ import com.android.documentsui.selection.SelectionHelper;
 import com.android.documentsui.testing.TestModel;
 import com.android.documentsui.testing.SelectionHelpers;
 import com.android.documentsui.testing.TestFeatures;
+import com.android.documentsui.testing.TestGridLayoutManager;
 import com.android.documentsui.testing.TestRecyclerView;
 
 import java.util.ArrayList;
@@ -39,12 +41,16 @@ public class FocusManagerTest extends AndroidTestCase {
 
     private FocusManager mManager;
     private TestRecyclerView mView;
+    private TestGridLayoutManager mTestGridLayoutManager;
     private SelectionHelper mSelectionMgr;
     private TestFeatures mFeatures;
 
     @Override
     public void setUp() throws Exception {
         mView = TestRecyclerView.create(ITEMS);
+        mTestGridLayoutManager = TestGridLayoutManager.create();
+        mView.setLayoutManager(mTestGridLayoutManager);
+
         mSelectionMgr = SelectionHelpers.createTestInstance(ITEMS);
         mFeatures = new TestFeatures();
         mManager = new FocusManager(mFeatures, mSelectionMgr, null, null, 0)
@@ -73,6 +79,11 @@ public class FocusManagerTest extends AndroidTestCase {
         assertFalse(mManager.focusDirectoryList());
     }
 
+    public void testFocusDirectoryList_noVisibleItems() {
+        mTestGridLayoutManager.setFirstVisibleItemPosition(RecyclerView.NO_POSITION);
+        assertFalse(mManager.focusDirectoryList());
+    }
+
     public void testFocusDirectoryList_hasSelection() {
         mSelectionMgr.select("0");
         assertFalse(mManager.focusDirectoryList());