diff --git a/bramble-core/src/test/java/org/briarproject/bramble/mailbox/ContactMailboxClientTest.java b/bramble-core/src/test/java/org/briarproject/bramble/mailbox/ContactMailboxClientTest.java
new file mode 100644
index 000000000..a264b7650
--- /dev/null
+++ b/bramble-core/src/test/java/org/briarproject/bramble/mailbox/ContactMailboxClientTest.java
@@ -0,0 +1,136 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.jmock.Expectations;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.briarproject.bramble.api.mailbox.MailboxConstants.CLIENT_SUPPORTS;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.bramble.test.TestUtils.getContactId;
+import static org.briarproject.bramble.test.TestUtils.getMailboxProperties;
+
+public class ContactMailboxClientTest extends BrambleMockTestCase {
+
+	private final MailboxWorkerFactory workerFactory =
+			context.mock(MailboxWorkerFactory.class);
+	private final ConnectivityChecker connectivityChecker =
+			context.mock(ConnectivityChecker.class);
+	private final TorReachabilityMonitor reachabilityMonitor =
+			context.mock(TorReachabilityMonitor.class);
+	private final MailboxWorker uploadWorker =
+			context.mock(MailboxWorker.class, "uploadWorker");
+	private final MailboxWorker downloadWorker =
+			context.mock(MailboxWorker.class, "downloadWorker");
+
+	private final MailboxProperties properties =
+			getMailboxProperties(false, CLIENT_SUPPORTS);
+	private final MailboxFolderId inboxId =
+			requireNonNull(properties.getInboxId());
+	private final MailboxFolderId outboxId =
+			requireNonNull(properties.getOutboxId());
+	private final ContactId contactId = getContactId();
+
+	private ContactMailboxClient client;
+
+	@Before
+	public void setUp() {
+		client = new ContactMailboxClient(workerFactory, connectivityChecker,
+				reachabilityMonitor);
+	}
+
+	@Test
+	public void testStartAndDestroyWithNoContactsAssigned() {
+		client.start();
+		client.destroy();
+	}
+
+	@Test
+	public void testAssignContactForUploadAndDestroyClient() {
+		client.start();
+
+		// When the contact is assigned, the worker should be created and
+		// started
+		expectCreateAndStartUploadWorker();
+		client.assignContactForUpload(contactId, properties, outboxId);
+
+		// When the client is destroyed, the worker should be destroyed
+		expectDestroyWorker(uploadWorker);
+		client.destroy();
+	}
+
+	@Test
+	public void testAssignAndDeassignContactForUpload() {
+		client.start();
+
+		// When the contact is assigned, the worker should be created and
+		// started
+		expectCreateAndStartUploadWorker();
+		client.assignContactForUpload(contactId, properties, outboxId);
+
+		// When the contact is deassigned, the worker should be destroyed
+		expectDestroyWorker(uploadWorker);
+		client.deassignContactForUpload(contactId);
+		context.assertIsSatisfied();
+
+		client.destroy();
+	}
+
+	@Test
+	public void assignContactForDownloadAndDestroyClient() {
+		client.start();
+
+		// When the contact is assigned, the worker should be created and
+		// started
+		expectCreateAndStartDownloadWorker();
+		client.assignContactForDownload(contactId, properties, inboxId);
+
+		// When the client is destroyed, the worker should be destroyed
+		expectDestroyWorker(downloadWorker);
+		client.destroy();
+	}
+
+	@Test
+	public void assignAndDeassignContactForDownload() {
+		client.start();
+
+		// When the contact is assigned, the worker should be created and
+		// started
+		expectCreateAndStartDownloadWorker();
+		client.assignContactForDownload(contactId, properties, inboxId);
+
+		// When the contact is deassigned, the worker should be destroyed
+		expectDestroyWorker(downloadWorker);
+		client.deassignContactForDownload(contactId);
+		context.assertIsSatisfied();
+
+		client.destroy();
+	}
+
+	private void expectCreateAndStartUploadWorker() {
+		context.checking(new Expectations() {{
+			oneOf(workerFactory).createUploadWorker(connectivityChecker,
+					properties, outboxId, contactId);
+			will(returnValue(uploadWorker));
+			oneOf(uploadWorker).start();
+		}});
+	}
+
+	private void expectCreateAndStartDownloadWorker() {
+		context.checking(new Expectations() {{
+			oneOf(workerFactory).createDownloadWorkerForContactMailbox(
+					connectivityChecker, reachabilityMonitor, properties);
+			will(returnValue(downloadWorker));
+			oneOf(downloadWorker).start();
+		}});
+	}
+
+	private void expectDestroyWorker(MailboxWorker worker) {
+		context.checking(new Expectations() {{
+			oneOf(worker).destroy();
+		}});
+	}
+}