diff --git a/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java b/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java
new file mode 100644
index 0000000..ca1994f
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+++ b/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java
@@ -0,0 +1,112 @@
+/*
+ * 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.server.wm;
+
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD;
+import static android.app.WindowConfiguration.WINDOWING_MODE_PINNED;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.Before;
+import org.junit.After;
+
+import android.platform.test.annotations.Presubmit;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+/**
+ * Tests for the {@link DisplayContent.TaskStackContainers} container in {@link DisplayContent}.
+ *
+ * Build/Install/Run:
+ *  bit FrameworksServicesTests:com.android.server.wm.TaskStackContainersTests
+ */
+@SmallTest
+@Presubmit
+@RunWith(AndroidJUnit4.class)
+public class TaskStackContainersTests extends WindowTestsBase {
+
+    private TaskStack mPinnedStack;
+
+    @Before
+    public void setUp() throws Exception {
+        super.setUp();
+        mPinnedStack = createStackControllerOnStackOnDisplay(
+                WINDOWING_MODE_PINNED, ACTIVITY_TYPE_STANDARD, mDisplayContent).mContainer;
+        // Stack should contain visible app window to be considered visible.
+        final Task pinnedTask = createTaskInStack(mPinnedStack, 0 /* userId */);
+        assertFalse(mPinnedStack.isVisible());
+        final WindowTestUtils.TestAppWindowToken pinnedApp =
+                WindowTestUtils.createTestAppWindowToken(mDisplayContent);
+        pinnedTask.addChild(pinnedApp, 0 /* addPos */);
+        assertTrue(mPinnedStack.isVisible());
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        mPinnedStack.removeImmediately();
+    }
+
+    @Test
+    public void testStackPositionChildAt() throws Exception {
+        // Test that always-on-top stack can't be moved to position other than top.
+        final TaskStack stack1 = createTaskStackOnDisplay(mDisplayContent);
+        final TaskStack stack2 = createTaskStackOnDisplay(mDisplayContent);
+
+        final WindowContainer taskStackContainer = stack1.getParent();
+
+        final int stack1Pos = taskStackContainer.mChildren.indexOf(stack1);
+        final int stack2Pos = taskStackContainer.mChildren.indexOf(stack2);
+        final int pinnedStackPos = taskStackContainer.mChildren.indexOf(mPinnedStack);
+        assertGreaterThan(pinnedStackPos, stack2Pos);
+        assertGreaterThan(stack2Pos, stack1Pos);
+
+        taskStackContainer.positionChildAt(WindowContainer.POSITION_BOTTOM, mPinnedStack, false);
+        assertEquals(taskStackContainer.mChildren.get(stack1Pos), stack1);
+        assertEquals(taskStackContainer.mChildren.get(stack2Pos), stack2);
+        assertEquals(taskStackContainer.mChildren.get(pinnedStackPos), mPinnedStack);
+
+        taskStackContainer.positionChildAt(1, mPinnedStack, false);
+        assertEquals(taskStackContainer.mChildren.get(stack1Pos), stack1);
+        assertEquals(taskStackContainer.mChildren.get(stack2Pos), stack2);
+        assertEquals(taskStackContainer.mChildren.get(pinnedStackPos), mPinnedStack);
+    }
+
+    @Test
+    public void testStackPositionBelowPinnedStack() throws Exception {
+        // Test that no stack can be above pinned stack.
+        final TaskStack stack1 = createTaskStackOnDisplay(mDisplayContent);
+
+        final WindowContainer taskStackContainer = stack1.getParent();
+
+        final int stackPos = taskStackContainer.mChildren.indexOf(stack1);
+        final int pinnedStackPos = taskStackContainer.mChildren.indexOf(mPinnedStack);
+        assertGreaterThan(pinnedStackPos, stackPos);
+
+        taskStackContainer.positionChildAt(WindowContainer.POSITION_TOP, stack1, false);
+        assertEquals(taskStackContainer.mChildren.get(stackPos), stack1);
+        assertEquals(taskStackContainer.mChildren.get(pinnedStackPos), mPinnedStack);
+
+        taskStackContainer.positionChildAt(taskStackContainer.mChildren.size() - 1, stack1, false);
+        assertEquals(taskStackContainer.mChildren.get(stackPos), stack1);
+        assertEquals(taskStackContainer.mChildren.get(pinnedStackPos), mPinnedStack);
+    }
+}