Fix #309: make channelName available in Postprocessor script

The Postprocessor scope derives channelName from
message.getMergedConnectorMessage().getChannelName(), but
Message.getMergedConnectorMessage() never populated channelName on the
merged ConnectorMessage. As a result the channelName variable was null
in Postprocessor scripts, even though it is available in Deploy,
Undeploy, and Preprocessor scripts.

Populate channelName on the merged connector message from the Message's
own channelName, falling back to the source connector message's
channelName (which is reliably set during processing).

Adds MessageTest covering the three cases.

Signed-off-by: Giovanni Giannola <giogiannola@globalesm.com>

Author: ggiannola

donkey/src/main/java/com/mirth/connect/donkey/model/message/Message.java

@@ -117,6 +117,7 @@ public ConnectorMessage getMergedConnectorMessage() {
         if (mergedConnectorMessage == null) {
             mergedConnectorMessage = new ConnectorMessage();
             mergedConnectorMessage.setChannelId(channelId);
+            mergedConnectorMessage.setChannelName(channelName);
             mergedConnectorMessage.setMessageId(messageId);
             mergedConnectorMessage.setServerId(serverId);
             mergedConnectorMessage.setReceivedDate(receivedDate);
@@ -128,6 +129,9 @@ public ConnectorMessage getMergedConnectorMessage() {
             ConnectorMessage sourceConnectorMessage = connectorMessages.get(0);
 
             if (sourceConnectorMessage != null) {
+                if (mergedConnectorMessage.getChannelName() == null) {
+                    mergedConnectorMessage.setChannelName(sourceConnectorMessage.getChannelName());
+                }
                 mergedConnectorMessage.setRaw(sourceConnectorMessage.getRaw());
                 mergedConnectorMessage.setProcessedRaw(sourceConnectorMessage.getProcessedRaw());
                 sourceMap = sourceConnectorMessage.getSourceMap();

donkey/src/test/java/com/mirth/connect/donkey/test/MessageTest.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) Mirth Corporation. All rights reserved.
+ * 
+ * http://www.mirthcorp.com
+ * 
+ * The software in this package is published under the terms of the MPL license a copy of which has
+ * been included with this distribution in the LICENSE.txt file.
+ */
+
+package com.mirth.connect.donkey.test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import java.util.Calendar;
+
+import org.junit.Test;
+
+import com.mirth.connect.donkey.model.message.ConnectorMessage;
+import com.mirth.connect.donkey.model.message.Message;
+import com.mirth.connect.donkey.model.message.Status;
+
+public class MessageTest {
+
+    private static final String CHANNEL_ID = "test-channel-id";
+    private static final String CHANNEL_NAME = "Test Channel";
+    private static final String SERVER_ID = "test-server-id";
+    private static final long MESSAGE_ID = 1L;
+
+    /**
+     * Regression test for issue #309: the channelName variable was not available in the
+     * Postprocessor script because the merged connector message (used to build the postprocessor
+     * scope) never had its channelName populated.
+     */
+    @Test
+    public void mergedConnectorMessageInheritsChannelNameFromSourceConnectorMessage() {
+        Calendar receivedDate = Calendar.getInstance();
+
+        Message message = new Message();
+        message.setMessageId(MESSAGE_ID);
+        message.setChannelId(CHANNEL_ID);
+        message.setServerId(SERVER_ID);
+        message.setReceivedDate(receivedDate);
+
+        ConnectorMessage sourceConnectorMessage = new ConnectorMessage(CHANNEL_ID, CHANNEL_NAME, MESSAGE_ID, 0, SERVER_ID, receivedDate, Status.RECEIVED);
+        message.getConnectorMessages().put(0, sourceConnectorMessage);
+
+        assertEquals(CHANNEL_NAME, message.getMergedConnectorMessage().getChannelName());
+    }
+
+    /**
+     * When the Message itself carries a channelName, it should be propagated to the merged
+     * connector message even if (theoretically) the source connector message did not have one.
+     */
+    @Test
+    public void mergedConnectorMessageUsesMessageChannelNameWhenSet() {
+        Calendar receivedDate = Calendar.getInstance();
+
+        Message message = new Message();
+        message.setMessageId(MESSAGE_ID);
+        message.setChannelId(CHANNEL_ID);
+        message.setChannelName(CHANNEL_NAME);
+        message.setServerId(SERVER_ID);
+        message.setReceivedDate(receivedDate);
+
+        ConnectorMessage sourceConnectorMessage = new ConnectorMessage(CHANNEL_ID, null, MESSAGE_ID, 0, SERVER_ID, receivedDate, Status.RECEIVED);
+        message.getConnectorMessages().put(0, sourceConnectorMessage);
+
+        assertEquals(CHANNEL_NAME, message.getMergedConnectorMessage().getChannelName());
+    }
+
+    /**
+     * With no channel name available anywhere, the merged connector message channelName stays null
+     * (i.e. the fix does not fabricate a value).
+     */
+    @Test
+    public void mergedConnectorMessageChannelNameNullWhenUnavailable() {
+        Calendar receivedDate = Calendar.getInstance();
+
+        Message message = new Message();
+        message.setMessageId(MESSAGE_ID);
+        message.setChannelId(CHANNEL_ID);
+        message.setServerId(SERVER_ID);
+        message.setReceivedDate(receivedDate);
+
+        ConnectorMessage sourceConnectorMessage = new ConnectorMessage(CHANNEL_ID, null, MESSAGE_ID, 0, SERVER_ID, receivedDate, Status.RECEIVED);
+        message.getConnectorMessages().put(0, sourceConnectorMessage);
+
+        assertNull(message.getMergedConnectorMessage().getChannelName());
+    }
+}