added TestCase to cover General Exception

Trigger IllegalArgumentException by adding a new Channel, and filling it with Integer.MAX value (not fitting in short range), catch the log and check for "IllegalArgumentException"
-> For me : easiest way to catch the logError

io.openems.edge.bridge.modbus/test/io/openems/edge/bridge/modbus/BridgeModbusTcpImplTest.java

@@ -1,6 +1,7 @@
 package io.openems.edge.bridge.modbus;
 
 import static io.openems.edge.bridge.modbus.api.ModbusComponent.ChannelId.MODBUS_COMMUNICATION_FAILED;
+import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 
@@ -24,6 +25,9 @@
 import io.openems.edge.common.test.ComponentTest;
 import io.openems.edge.common.test.TestUtils;
 
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+
 public class BridgeModbusTcpImplTest {
 
 	private static final int UNIT_ID = 1;
@@ -43,6 +47,8 @@ public void test() throws Exception {
 			var processImage = new SimpleProcessImage(UNIT_ID);
 			Register register100 = new SimpleRegister(123);
 			processImage.addRegister(100, register100);
+			Register register101 = new SimpleRegister(321);
+			processImage.addRegister(101, register101);
 			slave.addProcessImage(UNIT_ID, processImage);
 			slave.open();
 
@@ -91,15 +97,63 @@ public void test() throws Exception {
 		}
 	}
 
+	@Test
+	public void testTriggerLogIllegalArgumentException() throws Exception {
+		final ThrowingRunnable<Exception> sleep = () -> Thread.sleep(CYCLE_TIME);
+		var port = TestUtils.findRandomOpenPortOnAllLocalInterfaces();
+		ModbusSlave slave = null;
+		PrintStream originalOut = System.out;
+		ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+		try {
+			/*
+			 * Open Modbus/TCP Slave
+			 */
+			slave = ModbusSlaveFactory.createTCPSlave(port, 1);
+			var processImage = new SimpleProcessImage(UNIT_ID);
+			Register register100 = new SimpleRegister(123);
+			Register register101 = new SimpleRegister(Integer.MAX_VALUE); // this will cause the IllegalArgumentException
+			processImage.addRegister(100, register100);
+			processImage.addRegister(101, register101);
+			slave.addProcessImage(UNIT_ID, processImage);
+			slave.open();
+			System.setOut(new PrintStream(outContent));
+			/*
+			 * Instantiate Modbus-Bridge
+			 */
+			var sut = new BridgeModbusTcpImpl();
+			var test = new ComponentTest(sut) //
+					.activate(MyConfigTcp.create() //
+							.setId("modbus0") //
+							.setIp("127.0.0.1") //
+							.setPort(port) //
+							.setInvalidateElementsAfterReadErrors(1) //
+							.setLogVerbosity(LogVerbosity.NONE) //
+							.build());
+			test.addComponent(new MyModbusComponent("device0", sut, UNIT_ID));
+				test //
+						.next(new TestCase() //
+								.onAfterProcessImage(sleep)); //
+			assertTrue(outContent.toString().contains("IllegalArgumentException"));
+
+		} finally {
+			if (slave != null) {
+				slave.close();
+				System.setOut(originalOut);
+				System.out.println(outContent);
+			}
+		}
+	}
+
 	private static class MyModbusComponent extends DummyModbusComponent {
 
 		public MyModbusComponent(String id, AbstractModbusBridge bridge, int unitId) throws OpenemsException {
 			super(id, bridge, unitId, ChannelId.values());
 		}
 
 		public enum ChannelId implements io.openems.edge.common.channel.ChannelId {
-			REGISTER_100(Doc.of(OpenemsType.INTEGER)); //
-
+			REGISTER_100(Doc.of(OpenemsType.INTEGER)), //
+			REGISTER_101(Doc.of(OpenemsType.SHORT)), //
+			;
 			private final Doc doc;
 
 			private ChannelId(Doc doc) {
@@ -116,7 +170,8 @@ public Doc doc() {
 		protected ModbusProtocol defineModbusProtocol() {
 			return new ModbusProtocol(this, //
 					new FC3ReadRegistersTask(100, Priority.HIGH, //
-							m(ChannelId.REGISTER_100, new UnsignedWordElement(100)))); //
+							m(ChannelId.REGISTER_100, new UnsignedWordElement(100)),
+							m(ChannelId.REGISTER_101, new UnsignedWordElement(101)))); //
 		}
 
 	}