Introduce test fixtures

This also removes the powermock dependency. Although powermock is a
fine library, it currently prevents dropping Junit4. And since we only
use the Whitebox API of powermock, this simply replaced powermock's
Whitebox with our own.

smack-extensions/src/testFixtures/java/org/jivesoftware/util/ConnectionUtils.java

@@ -0,0 +1,138 @@
+/**
+ *
+ * Copyright the original author or authors
+ *
+ * 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 org.jivesoftware.util;
+
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.isA;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import org.jivesoftware.smack.SmackException;
+import org.jivesoftware.smack.StanzaCollector;
+import org.jivesoftware.smack.XMPPConnection;
+import org.jivesoftware.smack.XMPPException.XMPPErrorException;
+import org.jivesoftware.smack.filter.StanzaFilter;
+import org.jivesoftware.smack.packet.IQ;
+import org.jivesoftware.smack.packet.Stanza;
+import org.jivesoftware.smack.packet.StanzaFactory;
+import org.jivesoftware.smack.packet.id.StandardStanzaIdSource;
+
+import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
+
+import org.jxmpp.jid.DomainBareJid;
+import org.jxmpp.jid.EntityFullJid;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+
+/**
+ * A collection of utility methods to create mocked XMPP connections.
+ *
+ * @author Henning Staib
+ */
+public class ConnectionUtils {
+
+    /**
+     * Creates a mocked XMPP connection that stores every stanza that is send over this
+     * connection in the given protocol instance and returns the predefined answer packets
+     * form the protocol instance.
+     * <p>
+     * This mocked connection can used to collect packets that require a reply using a
+     * StanzaCollector.
+     *
+     * <pre>
+     * <code>
+     *   StanzaCollector collector = connection.createStanzaCollector(new PacketFilter());
+     *   connection.sendStanza(packet);
+     *   Stanza reply = collector.nextResult();
+     * </code>
+     * </pre>
+     *
+     * @param protocol protocol helper containing answer packets
+     * @param initiatorJID the user associated to the XMPP connection
+     * @return a mocked XMPP connection
+     * @throws SmackException if Smack detected an exceptional situation.
+     * @throws XMPPErrorException if there was an XMPP error returned.
+     * @throws InterruptedException if the calling thread was interrupted.
+     */
+    public static XMPPConnection createMockedConnection(final Protocol protocol,
+                    EntityFullJid initiatorJID) throws SmackException, XMPPErrorException, InterruptedException {
+
+        DomainBareJid xmppServer = initiatorJID.asDomainBareJid();
+
+        // mock XMPP connection
+        XMPPConnection connection = mock(XMPPConnection.class);
+        when(connection.getUser()).thenReturn(initiatorJID);
+        when(connection.getXMPPServiceDomain()).thenReturn(xmppServer);
+
+        final StanzaFactory stanzaFactory = new StanzaFactory(new StandardStanzaIdSource());
+        when(connection.getStanzaFactory()).thenReturn(stanzaFactory);
+
+        // mock packet collector
+        final StanzaCollector collector = mock(StanzaCollector.class);
+        when(connection.createStanzaCollector(isA(StanzaFilter.class))).thenReturn(
+                        collector);
+        Answer<StanzaCollector> collectorAndSend = new Answer<StanzaCollector>() {
+            @Override
+            public StanzaCollector answer(InvocationOnMock invocation) throws Throwable {
+                Stanza packet = (Stanza) invocation.getArguments()[0];
+                protocol.getRequests().add(packet);
+                return collector;
+            }
+
+        };
+        when(connection.createStanzaCollectorAndSend(isA(IQ.class))).thenAnswer(collectorAndSend);
+
+        // mock send method
+        Answer<Object> addIncoming = new Answer<Object>() {
+            @Override
+            public Object answer(InvocationOnMock invocation) throws Throwable {
+                protocol.getRequests().add((Stanza) invocation.getArguments()[0]);
+                return null;
+            }
+        };
+        doAnswer(addIncoming).when(connection).sendStanza(isA(Stanza.class));
+
+        // mock receive methods
+        Answer<Stanza> answer = new Answer<Stanza>() {
+            @Override
+            public Stanza answer(InvocationOnMock invocation) throws Throwable {
+                return protocol.getResponses().poll();
+            }
+        };
+        when(collector.nextResult(anyInt())).thenAnswer(answer);
+        when(collector.nextResult()).thenAnswer(answer);
+        Answer<Stanza> answerOrThrow = new Answer<Stanza>() {
+            @Override
+            public Stanza answer(InvocationOnMock invocation) throws Throwable {
+                Stanza packet = protocol.getResponses().poll();
+                if (packet == null) return packet;
+                XMPPErrorException.ifHasErrorThenThrow(packet);
+                return packet;
+            }
+        };
+        when(collector.nextResultOrThrow()).thenAnswer(answerOrThrow);
+        when(collector.nextResultOrThrow(anyLong())).thenAnswer(answerOrThrow);
+
+        // initialize service discovery manager for this connection
+        ServiceDiscoveryManager.getInstanceFor(connection);
+
+        return connection;
+    }
+
+}