diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java
new file mode 100644
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+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/util/FileDownloaderTest.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2018 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.example.android.systemupdatersample.util;
+
+import static junit.framework.Assert.assertEquals;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.example.android.systemupdatersample.tests.R;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+/**
+ * Tests for {@link FileDownloader}
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class FileDownloaderTest {
+
+    @Rule
+    public final ExpectedException thrown = ExpectedException.none();
+
+    private Context mTestContext;
+    private Context mTargetContext;
+
+    @Before
+    public void setUp() {
+        mTestContext = InstrumentationRegistry.getContext();
+        mTargetContext = InstrumentationRegistry.getTargetContext();
+    }
+
+    @Test
+    public void download_downloadsChunkOfZip() throws Exception {
+        // Prepare the target file
+        File packageFile = Paths
+                .get(mTargetContext.getCacheDir().getAbsolutePath(), "ota.zip")
+                .toFile();
+        Files.delete(packageFile.toPath());
+        Files.copy(mTestContext.getResources().openRawResource(R.raw.ota_002_package),
+                packageFile.toPath());
+        String url = "file://" + packageFile.getAbsolutePath();
+        // prepare where to download
+        File outFile = Paths
+                .get(mTargetContext.getCacheDir().getAbsolutePath(), "care_map.txt")
+                .toFile();
+        Files.delete(outFile.toPath());
+        // download a chunk of ota.zip
+        FileDownloader downloader = new FileDownloader(url, 160, 8, outFile);
+        downloader.download();
+        String downloadedContent = String.join("\n", Files.readAllLines(outFile.toPath()));
+        // Look at tools/create_test_ota.py
+        assertEquals("CARE_MAP", downloadedContent);
+    }
+
+}