diff --git a/common/device-side/device-info/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivity.java b/common/device-side/device-info/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivity.java
index 62e512c..f9de6eb 100644
--- a/common/device-side/device-info/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivity.java
+++ b/common/device-side/device-info/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivity.java
@@ -182,6 +182,17 @@
     /**
      * Start a new group of result.
      */
+    public void startGroup() {
+        try {
+            mJsonWriter.beginObject();
+        } catch (Exception e) {
+            error("Failed to begin JSON group: " + e.getMessage());
+        }
+    }
+
+    /**
+     * Start a new group of result with specified name.
+     */
     public void startGroup(String name) {
         try {
             mJsonWriter.name(name);
@@ -203,6 +214,41 @@
     }
 
     /**
+     * Start a new array of result.
+     */
+    public void startArray() {
+        try {
+            mJsonWriter.beginArray();
+        } catch (Exception e) {
+            error("Failed to begin JSON array: " + e.getMessage());
+        }
+    }
+
+    /**
+     * Start a new array of result with specified name.
+     */
+    public void startArray(String name) {
+        checkName(name);
+        try {
+            mJsonWriter.name(name);
+            mJsonWriter.beginArray();
+        } catch (Exception e) {
+            error("Failed to begin JSON array: " + e.getMessage());
+        }
+    }
+
+    /**
+     * Complete adding result to the last started array.
+     */
+    public void endArray() {
+        try {
+            mJsonWriter.endArray();
+        } catch (Exception e) {
+            error("Failed to end JSON group: " + e.getMessage());
+        }
+    }
+
+    /**
      * Add a double value result.
      */
     public void addResult(String name, double value) {
diff --git a/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivityTest.java b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivityTest.java
index 8a8a66c..d092f4e 100644
--- a/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivityTest.java
+++ b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/DeviceInfoActivityTest.java
@@ -25,15 +25,15 @@
 /**
  * Test for {@link DeviceInfoActivity}.
  */
-public class DeviceInfoActivityTest extends ActivityInstrumentationTestCase2<SampleDeviceInfo> {
+public class DeviceInfoActivityTest extends ActivityInstrumentationTestCase2<TestDeviceInfo> {
 
     private static final String EXPECTED_FILE_PATH =
-            "/storage/emulated/0/device-info-files/SampleDeviceInfo.deviceinfo.json";
+            "/storage/emulated/0/device-info-files/TestDeviceInfo.deviceinfo.json";
 
-    private SampleDeviceInfo mActivity;
+    private TestDeviceInfo mActivity;
 
     public DeviceInfoActivityTest() {
-        super(SampleDeviceInfo.class);
+        super(TestDeviceInfo.class);
     }
 
     @Override
@@ -59,7 +59,7 @@
         assertEquals("Incorrect file path", EXPECTED_FILE_PATH, resultFilePath);
         // Check json file content
         String jsonContent = readFile(resultFilePath);
-        assertEquals("Incorrect json output", ExampleObjects.sampleDeviceInfoJson(), jsonContent);
+        assertEquals("Incorrect json output", ExampleObjects.testDeviceInfoJson(), jsonContent);
     }
 
     private String readFile(String filePath) throws IOException {
diff --git a/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/ExampleObjects.java b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/ExampleObjects.java
index 92e7df1..570bdd5 100644
--- a/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/ExampleObjects.java
+++ b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/ExampleObjects.java
@@ -20,53 +20,73 @@
  */
 public final class ExampleObjects {
 
+    // Must match DeviceInfoActivity.MAX_STRING_VALUE_LENGTH and
+    // DeviceInfoActivity.MAX_ARRAY_LENGTH
     private static final int MAX_LENGTH = 1000;
 
-    private static final String SAMPLE_DEVICE_INFO_JSON = "{\n" +
-        "  \"foo\": {\n" +
-        "    \"foo_boolean\": true,\n" +
-        "    \"bar\": {\n" +
-        "      \"bar_string\": [\n" +
-        "        \"bar-string-1\",\n" +
-        "        \"bar-string-2\",\n" +
-        "        \"bar-string-3\"\n" +
-        "      ],\n" +
-        "      \"bar_boolean\": [\n" +
-        "        true,\n" +
-        "        false\n" +
-        "      ],\n" +
-        "      \"bar_double\": [\n" +
-        "        1.7976931348623157E308,\n" +
-        "        4.9E-324\n" +
-        "      ],\n" +
-        "      \"bar_int\": [\n" +
-        "        2147483647,\n" +
-        "        -2147483648\n" +
-        "      ],\n" +
-        "      \"bar_long\": [\n" +
-        "        9223372036854775807,\n" +
-        "        -9223372036854775808\n" +
+    private static final String TEST_DEVICE_INFO_JSON = "{\n" +
+        "  \"test_boolean\": true,\n" +
+        "  \"test_double\": 1.23456789,\n" +
+        "  \"test_int\": 123456789,\n" +
+        "  \"test_long\": 9223372036854775807,\n" +
+        "  \"test_string\": \"test string\",\n" +
+        "  \"test_strings\": [\n" +
+        "    \"test string 1\",\n" +
+        "    \"test string 2\",\n" +
+        "    \"test string 3\"\n" +
+        "  ],\n" +
+        "  \"test_group\": {\n" +
+        "    \"test_boolean\": false,\n" +
+        "    \"test_double\": 9.87654321,\n" +
+        "    \"test_int\": 987654321,\n" +
+        "    \"test_long\": 9223372036854775807,\n" +
+        "    \"test_string\": \"test group string\",\n" +
+        "    \"test_strings\": [\n" +
+        "      \"test group string 1\",\n" +
+        "      \"test group string 2\",\n" +
+        "      \"test group string 3\"\n" +
+        "    ]\n" +
+        "  },\n" +
+        "  \"test_groups\": [\n" +
+        "    {\n" +
+        "      \"test_string\": \"test groups string 1\",\n" +
+        "      \"test_strings\": [\n" +
+        "        \"test groups string 1-1\",\n" +
+        "        \"test groups string 1-2\",\n" +
+        "        \"test groups string 1-3\"\n" +
         "      ]\n" +
         "    },\n" +
-        "    \"foo_double\": 1.7976931348623157E308,\n" +
-        "    \"foo_int\": 2147483647,\n" +
-        "    \"foo_long\": 9223372036854775807,\n" +
-        "    \"foo_string\": \"foo-string\",\n" +
-        "    \"long_string\": \"%s\",\n" +
-        "    \"long_int_array\": [\n%s" +
-        "    ]\n" +
-        "  }\n" +
+        "    {\n" +
+        "      \"test_string\": \"test groups string 2\",\n" +
+        "      \"test_strings\": [\n" +
+        "        \"test groups string 2-1\",\n" +
+        "        \"test groups string 2-2\",\n" +
+        "        \"test groups string 2-3\"\n" +
+        "      ]\n" +
+        "    },\n" +
+        "    {\n" +
+        "      \"test_string\": \"test groups string 3\",\n" +
+        "      \"test_strings\": [\n" +
+        "        \"test groups string 3-1\",\n" +
+        "        \"test groups string 3-2\",\n" +
+        "        \"test groups string 3-3\"\n" +
+        "      ]\n" +
+        "    }\n" +
+        "  ],\n" +
+        "  \"max_length_string\": \"%s\",\n" +
+        "  \"max_num_ints\": [\n%s" +
+        "  ]\n" +
         "}\n";
 
-    public static String sampleDeviceInfoJson() {
+    public static String testDeviceInfoJson() {
         StringBuilder longStringSb = new StringBuilder();
         StringBuilder longArraySb = new StringBuilder();
         int lastNum = MAX_LENGTH - 1;
         for (int i = 0; i < MAX_LENGTH; i++) {
             longStringSb.append("a");
-            longArraySb.append(String.format("      %d%s\n", i, ((i == lastNum)? "" : ",")));
+            longArraySb.append(String.format("    %d%s\n", i, ((i == lastNum)? "" : ",")));
         }
-        return String.format(SAMPLE_DEVICE_INFO_JSON,
+        return String.format(TEST_DEVICE_INFO_JSON,
             longStringSb.toString(), longArraySb.toString());
     }
 }
\ No newline at end of file
diff --git a/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/TestDeviceInfo.java b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/TestDeviceInfo.java
new file mode 100644
index 0000000..7f82942
--- /dev/null
+++ b/common/device-side/device-info/tests/src/com/android/compatibility/common/deviceinfo/TestDeviceInfo.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2015 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.compatibility.common.deviceinfo;
+
+import android.os.Bundle;
+
+import java.lang.StringBuilder;
+
+/**
+ * Collector for testing DeviceInfoActivity
+ */
+public class TestDeviceInfo extends DeviceInfoActivity {
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+    }
+
+    @Override
+    protected void collectDeviceInfo() {
+
+        // Test primitive results
+        addResult("test_boolean", true);
+        addResult("test_double", 1.23456789);
+        addResult("test_int", 123456789);
+        addResult("test_long", Long.MAX_VALUE);
+        addResult("test_string", "test string");
+        addArray("test_strings", new String[] {
+            "test string 1",
+            "test string 2",
+            "test string 3",
+        });
+
+        // Test group
+        startGroup("test_group");
+        addResult("test_boolean", false);
+        addResult("test_double", 9.87654321);
+        addResult("test_int", 987654321);
+        addResult("test_long", Long.MAX_VALUE);
+        addResult("test_string", "test group string");
+        addArray("test_strings", new String[] {
+            "test group string 1",
+            "test group string 2",
+            "test group string 3"
+        });
+        endGroup(); // test_group
+
+        // Test array of groups
+        startArray("test_groups");
+        for (int i = 1; i < 4; i++) {
+            startGroup();
+            addResult("test_string", "test groups string " + i);
+            addArray("test_strings", new String[] {
+                "test groups string " + i + "-1",
+                "test groups string " + i + "-2",
+                "test groups string " + i + "-3"
+            });
+            endGroup();
+        }
+        endArray(); // test_groups
+
+        // Test max
+        StringBuilder sb = new StringBuilder();
+        int[] arr = new int[1001];
+        for (int i = 0; i < 1001; i++) {
+            sb.append("a");
+            arr[i] = i;
+        }
+        addResult("max_length_string", sb.toString());
+        addArray("max_num_ints", arr);
+    }
+}