diff --git a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
index b99aca2..5aee135 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
@@ -264,7 +264,7 @@
     static final int PTNODE_SHORTCUT_LIST_SIZE_SIZE = 2;
 
     // These values are used only by version 4 or later.
-    static final String TRIE_FILE_EXTENSION = ".trie";
+    public static final String TRIE_FILE_EXTENSION = ".trie";
     static final String FREQ_FILE_EXTENSION = ".freq";
     static final String UNIGRAM_TIMESTAMP_FILE_EXTENSION = ".timestamp";
     // tat = Terminal Address Table
diff --git a/tests/src/com/android/inputmethod/latin/Ver4BinaryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/Ver4BinaryDictionaryTests.java
new file mode 100644
index 0000000..25fb1c2
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/Ver4BinaryDictionaryTests.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2013 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;
+
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.LargeTest;
+import android.util.Log;
+
+import com.android.inputmethod.latin.makedict.DictEncoder;
+import com.android.inputmethod.latin.makedict.FormatSpec;
+import com.android.inputmethod.latin.makedict.FusionDictionary;
+import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
+import com.android.inputmethod.latin.makedict.Ver4DictEncoder;
+import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Locale;
+
+@LargeTest
+public class Ver4BinaryDictionaryTests extends AndroidTestCase {
+    private static final String TAG = Ver4BinaryDictionaryTests.class.getSimpleName();
+    private static final String TEST_LOCALE = "test";
+    private static final FormatSpec.FormatOptions FORMAT_OPTIONS =
+            new FormatSpec.FormatOptions(4, true /* supportsDynamicUpdate */);
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        super.tearDown();
+    }
+
+    // TODO: remove after native code support dictionary creation.
+    private DictionaryOptions getDictionaryOptions(final String id, final String version) {
+        final DictionaryOptions options = new DictionaryOptions(new HashMap<String, String>(),
+                false /* germanUmlautProcessing */, false /* frenchLigatureProcessing */);
+        options.mAttributes.put("version", version);
+        options.mAttributes.put("dictionary", id);
+        return options;
+    }
+
+    // TODO: remove after native code support dictionary creation.
+    private File getTrieFile(final String id, final String version) {
+        return new File(getContext().getCacheDir() + "/" + id + "." + version, 
+                TEST_LOCALE + "." + version + FormatSpec.TRIE_FILE_EXTENSION);
+    }
+
+    public void testIsValidDictionary() {
+        final String dictVersion = Long.toString(System.currentTimeMillis());
+        final File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
+
+        BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
+                0 /* offset */, trieFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+        assertFalse(binaryDictionary.isValidDictionary());
+
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
+                getDictionaryOptions(TEST_LOCALE, dictVersion));
+        DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
+        try {
+            encoder.writeDictionary(dict, FORMAT_OPTIONS);
+        } catch (IOException e) {
+            Log.e(TAG, "IOException while writing dictionary", e);
+        } catch (UnsupportedFormatException e) {
+            Log.e(TAG, "Unsupported format", e);
+        }
+
+        binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
+                0 /* offset */, trieFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+        assertTrue(binaryDictionary.isValidDictionary());
+    }
+}