Bael 9410 (#18758)

* BAEL-9410

* Remove log4j example

---------

Co-authored-by: Wynn Teo <[email protected]>

Author: wynnteo

logging-modules/log4j/src/test/java/com/baeldung/logging/log4j2/DynamicFileAppenderUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.logging.log4j2;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import org.apache.log4j.xml.DOMConfigurator;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.junit.jupiter.api.Test;
+
+public class DynamicFileAppenderUnitTest {
+    @Test
+    public void givenLog4j2DynamicFileNameConfig_whenLogToFile_thenFileIsCreated() throws Exception {
+        System.setProperty("log4j.configurationFile", "src/test/resources/log4j2-dynamic.xml");
+        System.setProperty("logfilename", "app-dynamic-log");
+
+        Logger logger = LogManager.getLogger(DynamicFileAppenderUnitTest.class);
+        String expectedMessage = "This is an ERROR log message to the same file.";
+        logger.error(expectedMessage);
+
+        File file = new File("app-dynamic-log.log");
+        assertTrue(file.exists(), "Log file should be created dynamically.");
+
+        String content = Files.readString(file.toPath());
+        assertTrue(content.contains(expectedMessage), "Log file should contain the logged message.");
+    }
+}

logging-modules/log4j/src/test/resources/log4j2-dynamic.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+    <Appenders>
+        <File name="DynamicFileAppender" fileName="${sys:logfilename}.log">
+            <PatternLayout pattern="%d [%t] %-5level %logger - %msg%n"/>
+        </File>
+    </Appenders>
+    <Loggers>
+        <Root level="INFO">
+            <AppenderRef ref="DynamicFileAppender"/>
+        </Root>
+    </Loggers>
+</Configuration>