diff --git a/httpclient5/src/test/java/org/apache/hc/client5/http/impl/InMemoryDnsResolverTest.java b/httpclient5/src/test/java/org/apache/hc/client5/http/impl/InMemoryDnsResolverTest.java
new file mode 100644
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--- /dev/null
+++ b/httpclient5/src/test/java/org/apache/hc/client5/http/impl/InMemoryDnsResolverTest.java
@@ -0,0 +1,68 @@
+/*
+ * ====================================================================
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+
+package org.apache.hc.client5.http.impl;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests {@link InMemoryDnsResolver}.
+ */
+public class InMemoryDnsResolverTest {
+
+    @Test
+    void resolve() throws UnknownHostException {
+        final InMemoryDnsResolver resolver = new InMemoryDnsResolver();
+        final String hostString = "127.0.0.1";
+        final byte[] address = new byte[] { 127, 0, 0, 1 };
+        resolver.add(hostString, InetAddress.getByAddress(hostString, address));
+        final InetAddress[] result1 = resolver.resolve(hostString);
+        assertEquals(1, result1.length);
+        assertArrayEquals(address, result1[0].getAddress());
+    }
+
+    @Test
+    void resolveIPv6ZoneId() throws UnknownHostException {
+        final InMemoryDnsResolver resolver = new InMemoryDnsResolver();
+        final String hostStr = "[fe80::221:b7ff:fe8a:57d5%en4]";
+        final byte[] address = new byte[] { (byte) 0xfe, (byte) 0x80, 0, 0, 0, 0, 0, 0, 0x02, 0x21, (byte) 0xb7, (byte) 0xff, (byte) 0xfe, (byte) 0x8a, 0x57,
+                (byte) 0xd5 };
+        resolver.add(hostStr, InetAddress.getByAddress(hostStr, address));
+        // This is an IPv6 address literal with zone ID
+        final InetAddress[] result = resolver.resolve(hostStr);
+        assertEquals(1, result.length);
+        assertArrayEquals(address, result[0].getAddress());
+
+    }
+
+}