diff --git a/staticlibs/tests/unit/jarjar-rules.txt b/staticlibs/tests/unit/jarjar-rules.txt
index fceccfb..0f131b2 100644
--- a/staticlibs/tests/unit/jarjar-rules.txt
+++ b/staticlibs/tests/unit/jarjar-rules.txt
@@ -1,6 +1,7 @@
 # TODO: move the classes to the target package in java
-rule android.net.util.IpRange* com.android.net.module.util.IpRange@1
-rule android.net.util.MacAddressUtils* com.android.net.module.util.MacAddressUtils@1
-rule android.net.util.LinkPropertiesUtils* com.android.net.module.util.LinkPropertiesUtils@1
-rule android.net.util.NetUtils* com.android.net.module.util.NetUtils@1
-rule android.net.util.nsd.** com.android.net.module.util.nsd.@1
+rule android.net.util.IpRange* com.android.net.moduletests.util.IpRange@1
+rule android.net.util.MacAddressUtils* com.android.net.moduletests.util.MacAddressUtils@1
+rule android.net.util.LinkPropertiesUtils* com.android.net.moduletests.util.LinkPropertiesUtils@1
+rule android.net.util.NetUtils* com.android.net.moduletests.util.NetUtils@1
+rule android.net.util.nsd.** com.android.net.moduletests.util.nsd.@1
+rule com.android.net.module.util.** com.android.net.moduletests.util.@1
diff --git a/staticlibs/tests/unit/src/android/net/util/StructTest.java b/staticlibs/tests/unit/src/android/net/util/StructTest.java
new file mode 100644
index 0000000..2d35891
--- /dev/null
+++ b/staticlibs/tests/unit/src/android/net/util/StructTest.java
@@ -0,0 +1,492 @@
+/*
+ * Copyright (C) 2020 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 android.net.util;
+
+import static com.android.testutils.MiscAsserts.assertThrows;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import android.net.IpPrefix;
+import android.net.util.Struct.Field;
+import android.net.util.Struct.Type;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.internal.util.HexDump;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.math.BigInteger;
+import java.net.InetAddress;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Arrays;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class StructTest {
+
+    // IPv6, 0 bytes of options, ifindex 15715755: 0x00efcdab, type 134 (RA), code 0, padding.
+    private static final String HDR_EMPTY = "0a00" + "0000" + "abcdef00" + "8600000000000000";
+
+    // BE16: 0xfeff, BE32: 0xfeffffff, BE64: 0xfffffffffffffffe, 0x7effffffffffffff
+    private static final String NETWORK_ORDER_MSG = "feff" + "feffffff" + "fffffffffffffffe"
+            + "7effffffffffffff";
+
+    // S8: 0x7f, S16: 0x7fff, S32: 0x7fffffff, S64: 0x7fffffffffffffff
+    private static final String SIGNED_DATA = "7f" + "ff7f" + "ffffff7f" + "ffffffffffffff7f";
+
+    // nS8: 0x81, nS16: 0x8001, nS32: 0x80000001, nS64: 800000000000000001
+    private static final String SIGNED_NEGATIVE_DATA = "81" + "0180" + "01000080"
+            + "0100000000000080";
+
+    // U8: 0xff, U16: 0xffff, U32: 0xffffffff, U64: 0xffffffffffffffff, U63: 0x7fffffffffffffff;
+    private static final String UNSIGNED_DATA = "ff" + "ffff" + "ffffffff" + "ffffffffffffffff"
+            + "ffffffffffffff7f";
+
+    // PREF64 option, 2001:db8:3:4:5:6::/96, lifetime: 10064
+    private static final String OPT_PREF64 = "2750" + "20010db80003000400050006";
+
+    private <T> T doParsingMessageTest(final String hexString, Class<T> clazz) {
+        final ByteBuffer buf = toByteBuffer(hexString);
+        buf.order(ByteOrder.LITTLE_ENDIAN);
+        return Struct.parse(clazz, buf);
+    }
+
+    static class HeaderMsgWithConstructor extends Struct {
+        static int sType;
+        static int sLength;
+
+        @Field(order = 0, type = Type.U8, padding = 1)
+        final short mFamily;
+        @Field(order = 1, type = Type.U16)
+        final int mLen;
+        @Field(order = 2, type = Type.S32)
+        final int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        final short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        final short mIcmpCode;
+
+        HeaderMsgWithConstructor(final short family, final int len, final int ifindex,
+                final short type, final short code) {
+            mFamily = family;
+            mLen = len;
+            mIfindex = ifindex;
+            mIcmpType = type;
+            mIcmpCode = code;
+        }
+    }
+
+    @Test
+    public void testClassWithExplicitConstructor() {
+        final HeaderMsgWithConstructor msg = doParsingMessageTest(HDR_EMPTY,
+                HeaderMsgWithConstructor.class);
+        assertEquals(10, msg.mFamily);
+        assertEquals(0, msg.mLen);
+        assertEquals(15715755, msg.mIfindex);
+        assertEquals(134, msg.mIcmpType);
+        assertEquals(0, msg.mIcmpCode);
+    }
+
+    static class HeaderMsgWithoutConstructor extends Struct {
+        static int sType;
+        static int sLength;
+
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testClassWithDefaultConstrcutor() {
+        final HeaderMsgWithoutConstructor msg = doParsingMessageTest(HDR_EMPTY,
+                HeaderMsgWithoutConstructor.class);
+        assertEquals(10, msg.mFamily);
+        assertEquals(0, msg.mLen);
+        assertEquals(15715755, msg.mIfindex);
+        assertEquals(134, msg.mIcmpType);
+        assertEquals(0, msg.mIcmpCode);
+    }
+
+    static class HeaderMessage {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_NotSubClass() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessage.class, buf));
+    }
+
+    static class HeaderMessageMissingAnnotation extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        int mIfindex;
+        @Field(order = 2, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 3, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_MissingAnnotationField() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageMissingAnnotation.class, buf));
+    }
+
+    static class NetworkOrderMessage extends Struct {
+        @Field(order = 0, type = Type.BE16)
+        final int mBE16;
+        @Field(order = 1, type = Type.BE32)
+        final long mBE32;
+        @Field(order = 2, type = Type.BE64)
+        final BigInteger mBE64;
+        @Field(order = 3, type = Type.BE64)
+        final long mBE63;
+
+        NetworkOrderMessage(final int be16, final long be32, final BigInteger be64,
+                final long be63) {
+            mBE16 = be16;
+            mBE32 = be32;
+            mBE64 = be64;
+            mBE63 = be63;
+        }
+    }
+
+    @Test
+    public void testNetworkOrder() {
+        final NetworkOrderMessage msg = doParsingMessageTest(NETWORK_ORDER_MSG,
+                NetworkOrderMessage.class);
+        assertEquals(65279, msg.mBE16);
+        assertEquals(4278190079L, msg.mBE32);
+        assertEquals(new BigInteger("18374686479671623679"), msg.mBE64);
+        assertEquals(9151314442816847871L, msg.mBE63);
+    }
+
+    static class UnsignedDataMessage extends Struct {
+        @Field(order = 0, type = Type.U8)
+        final short mU8;
+        @Field(order = 1, type = Type.U16)
+        final int mU16;
+        @Field(order = 2, type = Type.U32)
+        final long mU32;
+        @Field(order = 3, type = Type.U64)
+        final BigInteger mU64;
+        @Field(order = 4, type = Type.U64)
+        final long mU63;
+
+        UnsignedDataMessage(final short u8, final int u16, final long u32, final BigInteger u64,
+                final long u63) {
+            mU8 = u8;
+            mU16 = u16;
+            mU32 = u32;
+            mU64 = u64;
+            mU63 = u63;
+        }
+    }
+
+    @Test
+    public void testUnsignedData() {
+        final UnsignedDataMessage msg = doParsingMessageTest(UNSIGNED_DATA,
+                UnsignedDataMessage.class);
+        assertEquals(255, msg.mU8);
+        assertEquals(65535, msg.mU16);
+        assertEquals(4294967295L, msg.mU32);
+        assertEquals(new BigInteger("18446744073709551615"), msg.mU64);
+        assertEquals(9223372036854775807L, msg.mU63);
+    }
+
+    static class SignedDataMessage extends Struct {
+        @Field(order = 0, type = Type.S8)
+        final byte mS8;
+        @Field(order = 1, type = Type.S16)
+        final short mS16;
+        @Field(order = 2, type = Type.S32)
+        final int mS32;
+        @Field(order = 3, type = Type.S64)
+        final long mS64;
+        @Field(order = 4, type = Type.S8)
+        final byte mNS8;
+        @Field(order = 5, type = Type.S16)
+        final short mNS16;
+        @Field(order = 6, type = Type.S32)
+        final int mNS32;
+        @Field(order = 7, type = Type.S64)
+        final long mNS64;
+
+        SignedDataMessage(final byte s8, final short s16, final int s32, final long s64,
+                final byte nS8, final short nS16, final int nS32, final long nS64) {
+            mS8 = s8;
+            mS16 = s16;
+            mS32 = s32;
+            mS64 = s64;
+            mNS8 = nS8;
+            mNS16 = nS16;
+            mNS32 = nS32;
+            mNS64 = nS64;
+        }
+    }
+
+    @Test
+    public void testSignedData() {
+        final SignedDataMessage msg = doParsingMessageTest(SIGNED_DATA + SIGNED_NEGATIVE_DATA,
+                SignedDataMessage.class);
+        assertEquals(127, msg.mS8);
+        assertEquals(32767, msg.mS16);
+        assertEquals(2147483647, msg.mS32);
+        assertEquals(9223372036854775807L, msg.mS64);
+
+        assertEquals(-127, msg.mNS8);
+        assertEquals(-32767, msg.mNS16);
+        assertEquals(-2147483647, msg.mNS32);
+        assertEquals(-9223372036854775807L, msg.mNS64);
+    }
+
+    static class HeaderMessageWithDuplicateOrder extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 2, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 3, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_DuplicateFieldOrder() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageWithDuplicateOrder.class, buf));
+    }
+
+    static class HeaderMessageWithNegativeOrder extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = -4, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_NegativeFieldOrder() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageWithNegativeOrder.class, buf));
+    }
+
+    static class HeaderMessageOutOfIndexBounds extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 5, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_OutOfIndexBounds() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageOutOfIndexBounds.class, buf));
+    }
+
+    static class HeaderMessageMismatchedPrimitiveType extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        short mFamily;
+        @Field(order = 1, type = Type.U16)
+        short mLen; // should be integer
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        short mIcmpCode;
+    }
+
+    @Test
+    public void testInvalidClass_MismatchedPrimitiveDataType() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageMismatchedPrimitiveType.class, buf));
+    }
+
+    static class PrefixMessage extends Struct {
+        @Field(order = 0, type = Type.BE16)
+        final int mLifetime;
+        @Field(order = 1, type = Type.ByteArray, arraysize = 12)
+        final byte[] mPrefix;
+
+        PrefixMessage(final int lifetime, final byte[] prefix) {
+            mLifetime = lifetime;
+            mPrefix = prefix;
+        }
+    }
+
+    @Test
+    public void testPrefixArrayField() throws Exception {
+        final ByteBuffer buf = toByteBuffer(OPT_PREF64);
+        buf.order(ByteOrder.LITTLE_ENDIAN);
+
+        // The original PREF64 option message has just 12 bytes for prefix byte array
+        // (Highest 96 bits of the Prefix), copyOf pads the 128-bits IPv6 address with
+        // prefix and 4-bytes zeros.
+        final PrefixMessage msg = Struct.parse(PrefixMessage.class, buf);
+        final InetAddress addr = InetAddress.getByAddress(Arrays.copyOf(msg.mPrefix, 16));
+        final IpPrefix prefix = new IpPrefix(addr, 96);
+        assertEquals(10064, msg.mLifetime);
+        assertTrue(prefix.equals(new IpPrefix("2001:db8:3:4:5:6::/96")));
+    }
+
+    static class HeaderMessageWithMutableField extends Struct {
+        @Field(order = 0, type = Type.U8, padding = 1)
+        final short mFamily;
+        @Field(order = 1, type = Type.U16)
+        final int mLen;
+        @Field(order = 2, type = Type.S32)
+        int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        final short mIcmpCode;
+
+        HeaderMessageWithMutableField(final short family, final int len, final short code) {
+            mFamily = family;
+            mLen = len;
+            mIcmpCode = code;
+        }
+    }
+
+    @Test
+    public void testMixMutableAndImmutableFields() {
+        final ByteBuffer buf = toByteBuffer(HDR_EMPTY);
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(HeaderMessageWithMutableField.class, buf));
+    }
+
+    static class HeaderMsgWithStaticConstant extends Struct {
+        private static final String TAG = "HeaderMessage";
+        private static final int FIELD_COUNT = 5;
+
+        @Field(order = 0, type = Type.U8, padding = 1)
+        final short mFamily;
+        @Field(order = 1, type = Type.U16)
+        final int mLen;
+        @Field(order = 2, type = Type.S32)
+        final int mIfindex;
+        @Field(order = 3, type = Type.U8)
+        final short mIcmpType;
+        @Field(order = 4, type = Type.U8, padding = 6)
+        final short mIcmpCode;
+
+        HeaderMsgWithStaticConstant(final short family, final int len, final int ifindex,
+                final short type, final short code) {
+            mFamily = family;
+            mLen = len;
+            mIfindex = ifindex;
+            mIcmpType = type;
+            mIcmpCode = code;
+        }
+    }
+
+    @Test
+    public void testStaticConstantField() {
+        final HeaderMsgWithStaticConstant msg = doParsingMessageTest(HDR_EMPTY,
+                HeaderMsgWithStaticConstant.class);
+        assertEquals(10, msg.mFamily);
+        assertEquals(0, msg.mLen);
+        assertEquals(15715755, msg.mIfindex);
+        assertEquals(134, msg.mIcmpType);
+        assertEquals(0, msg.mIcmpCode);
+    }
+
+    static class MismatchedConstructor extends Struct {
+        @Field(order = 0, type = Type.U16) final int mInt1;
+        @Field(order = 1, type = Type.U16) final int mInt2;
+        MismatchedConstructor(String int1, String int2) {
+            mInt1 = Integer.valueOf(int1);
+            mInt2 = Integer.valueOf(int2);
+        }
+    }
+
+    @Test
+    public void testMisMatchedConstructor() {
+        final ByteBuffer buf = toByteBuffer("1234" + "5678");
+        assertThrows(IllegalArgumentException.class,
+                () -> Struct.parse(MismatchedConstructor.class, buf));
+    }
+
+    static class ClassWithTwoConstructors extends Struct {
+        @Field(order = 0, type = Type.U16) final int mInt1;
+        @Field(order = 1, type = Type.U16) final int mInt2;
+        ClassWithTwoConstructors(String int1, String int2) {
+            mInt1 = Integer.valueOf(int1);
+            mInt2 = Integer.valueOf(int2);
+        }
+        ClassWithTwoConstructors(int int1, int int2) {
+            mInt1 = int1;
+            mInt2 = int2;
+        }
+    }
+
+    @Test
+    public void testClassWithTwoConstructors() {
+        final ClassWithTwoConstructors msg = doParsingMessageTest("1234" + "5678",
+                ClassWithTwoConstructors.class);
+        assertEquals(13330 /* 0x3412 */, msg.mInt1);
+        assertEquals(30806 /* 0x7856 */, msg.mInt2);
+    }
+
+    private ByteBuffer toByteBuffer(final String hexString) {
+        return ByteBuffer.wrap(HexDump.hexStringToByteArray(hexString));
+    }
+}