diff --git a/tests/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryTests.java
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+++ b/tests/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryTests.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2014 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.inputmethod.latin.personalization;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import com.android.inputmethod.latin.BinaryDictionary;
+import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.DictionaryFacilitator;
+import com.android.inputmethod.latin.ExpandableBinaryDictionary;
+import com.android.inputmethod.latin.ExpandableBinaryDictionary.AddMultipleDictionaryEntriesCallback;
+import com.android.inputmethod.latin.makedict.CodePointUtils;
+import com.android.inputmethod.latin.settings.SpacingAndPunctuations;
+
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.LargeTest;
+import android.util.Log;
+
+/**
+ * Unit tests for personalization dictionary
+ */
+@LargeTest
+public class PersonalizationDictionaryTests extends AndroidTestCase {
+    private static final String TAG = PersonalizationDictionaryTests.class.getSimpleName();
+
+    private static final Locale LOCALE_EN_US = new Locale("en", "US");
+    private static final String DUMMY_PACKAGE_NAME = "test.package.name";
+    private static final long TIMEOUT_TO_WAIT_DICTIONARY_OPERATIONS_IN_SECONDS = 120;
+
+    private DictionaryFacilitator getDictionaryFacilitator() {
+        final ArrayList<String> dictTypes = new ArrayList<>();
+        dictTypes.add(Dictionary.TYPE_MAIN);
+        dictTypes.add(Dictionary.TYPE_PERSONALIZATION);
+        final DictionaryFacilitator dictionaryFacilitator = new DictionaryFacilitator();
+        dictionaryFacilitator.resetDictionariesForTesting(getContext(), LOCALE_EN_US, dictTypes,
+                new HashMap<String, File>(), new HashMap<String, Map<String, String>>());
+        return dictionaryFacilitator;
+    }
+
+    public void testAddManyTokens() {
+        final DictionaryFacilitator dictionaryFacilitator = getDictionaryFacilitator();
+        dictionaryFacilitator.clearPersonalizationDictionary();
+        final int dataChunkCount = 20;
+        final int wordCountInOneChunk = 2000;
+        final Random random = new Random(System.currentTimeMillis());
+        final int[] codePointSet = CodePointUtils.LATIN_ALPHABETS_LOWER;
+
+        final SpacingAndPunctuations spacingAndPunctuations =
+                new SpacingAndPunctuations(getContext().getResources());
+
+        final int timeStampInSeconds = (int)TimeUnit.MILLISECONDS.toSeconds(
+                System.currentTimeMillis());
+
+        for (int i = 0; i < dataChunkCount; i++) {
+            final ArrayList<String> tokens = new ArrayList<>();
+            for (int j = 0; j < wordCountInOneChunk; j++) {
+                tokens.add(CodePointUtils.generateWord(random, codePointSet));
+            }
+            final PersonalizationDataChunk personalizationDataChunk = new PersonalizationDataChunk(
+                    true /* inputByUser */, tokens, timeStampInSeconds, DUMMY_PACKAGE_NAME);
+            final CountDownLatch countDownLatch = new CountDownLatch(1);
+            final AddMultipleDictionaryEntriesCallback callback =
+                    new AddMultipleDictionaryEntriesCallback() {
+                        @Override
+                        public void onFinished() {
+                            countDownLatch.countDown();
+                        }
+                    };
+            dictionaryFacilitator.addEntriesToPersonalizationDictionary(personalizationDataChunk,
+                    spacingAndPunctuations, callback);
+            try {
+                countDownLatch.await(TIMEOUT_TO_WAIT_DICTIONARY_OPERATIONS_IN_SECONDS,
+                        TimeUnit.SECONDS);
+            } catch (InterruptedException e) {
+                Log.e(TAG, "Interrupted while waiting for finishing dictionary operations.", e);
+            }
+        }
+        dictionaryFacilitator.flushPersonalizationDictionary();
+        try {
+            dictionaryFacilitator.waitForLoadingDictionariesForTesting(
+                    TIMEOUT_TO_WAIT_DICTIONARY_OPERATIONS_IN_SECONDS, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            Log.e(TAG, "Interrupted while waiting for finishing dictionary operations.", e);
+        }
+        final String dictName = ExpandableBinaryDictionary.getDictName(
+                PersonalizationDictionary.NAME, LOCALE_EN_US, null /* dictFile */);
+        final File dictFile = ExpandableBinaryDictionary.getDictFile(
+                getContext(), dictName, null /* dictFile */);
+
+        final BinaryDictionary binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, 0 /* size */,
+                true /* useFullEditDistance */, LOCALE_EN_US, Dictionary.TYPE_PERSONALIZATION,
+                true /* isUpdatable */);
+        assertTrue(binaryDictionary.isValidDictionary());
+    }
+}