Add protected method to connect channel to streams

These methods can be overridden by subclasses of existing channels
to write to/read from streams,
for example, to replay some captured stream,
or just to do some tests based on ByteArrayInputStream.

Signed-off-by: Andrés Alcarraz <alcarraz@gmail.com>

jpos/src/main/java/org/jpos/iso/BaseChannel.java

@@ -291,6 +291,20 @@ protected void connect (Socket socket)
         setChanged();
         notifyObservers();
     }
+
+    /**
+     * Allow the channel to be connected to a pair of input and output streams.
+     * <p> 
+     * For instance for taking input from or outputting to a file or standard input/ouput.  
+     * 
+     * @param in Where to read from.
+     * @param out Where to write to.
+     */
+    protected void connect(InputStream in, OutputStream out) {
+        usable = in != null || out != null; //at least one of them has to be not null
+        if (in != null) serverIn = new DataInputStream(in);
+        if (out != null) serverOut = new DataOutputStream(out);
+    }
     protected void postConnectHook() throws IOException {
         // do nothing
     }

jpos/src/main/java/org/jpos/iso/channel/XMLChannel.java

@@ -22,9 +22,12 @@
 import org.jpos.iso.packager.XMLPackager;
 
 import java.io.BufferedReader;
+import java.io.DataInputStream;
 import java.io.EOFException;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.OutputStream;
 import java.net.ServerSocket;
 import java.net.Socket;
 
@@ -117,4 +120,9 @@ public void disconnect () throws IOException {
             reader.close ();
         reader = null;
     }
+
+    protected void connect(InputStream in, OutputStream out) {
+        super.connect(in, out);
+        reader = new BufferedReader(new InputStreamReader(in));
+    }
 }

jpos/src/test/java/org/jpos/iso/BaseChannelTest.java

@@ -18,18 +18,19 @@
 
 package org.jpos.iso;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertSame;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.Mockito.*;
 
 import static org.apache.commons.lang3.JavaVersion.JAVA_10;
 import static org.apache.commons.lang3.JavaVersion.JAVA_14;
 import static org.apache.commons.lang3.SystemUtils.isJavaVersionAtMost;
 
+import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.net.*;
@@ -1223,4 +1224,61 @@ public void testStreamReceive() throws Throwable {
         byte[] result = aSCIIChannel.streamReceive();
         assertEquals(0, result.length, "result.length");
     }
+
+    /**
+     * Connect using input stream, send a message and check what is written in the output stream 
+     * is the same as the packed message.
+     */
+    @Test
+    public void testConnectWithStreamsAndSend() throws ISOException, IOException {
+        BaseChannel ch = new PADChannel() {
+            @Override
+            public boolean isConnected() {
+                return serverOut != null;
+            }
+        };
+        ISOPackager packager = new ISO87APackager(); 
+        ch.setPackager(packager);
+
+        ISOMsg m = new ISOMsg();
+        m.setMTI("0800");
+        m.set(11, "000000");
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        ch.connect(null, out);
+        ch.send(m);
+        assertThat("Packed message should match output stream content", 
+                out.toByteArray(), is(equalTo(packager.pack(m))));
+        //Double check just to verify we are not comparing empty arrays.
+        m.set(41, "ABC");
+        assertThat("Packed message should not match a different message", 
+                out.toByteArray(), is(not(equalTo(packager.pack(m)))));
+    }
+
+    /**
+     * Connect using output stream, receive a message and check it is the same as sent. 
+     */
+    @Test
+    public void testConnectWithStreamsAndReceive() throws ISOException, IOException {
+        BaseChannel ch = new PADChannel(){
+            @Override
+            public boolean isConnected() {
+                return serverIn != null;
+            }
+        };
+        ISOPackager packager = new ISO87APackager();
+        ch.setPackager(packager);
+
+        ISOMsg m = new ISOMsg();
+        m.setMTI("0800");
+        m.set(11, "000000");
+        m.setPackager(packager);
+        ByteArrayInputStream in = new ByteArrayInputStream(m.pack());
+        ch.connect(in, null);
+        ISOMsg m2 = ch.receive();
+        assertThat("Received message should not be null", m2, is(notNullValue()));
+        assertThat("Received message should be the same as original",
+                m2.pack(), is(equalTo(m.pack())));
+
+    }
+
 }