Add assertions in unit test to test multiple appenders.

Author: phipag

powertools-logging/powertools-logging-log4j/src/main/java/software/amazon/lambda/powertools/logging/log4j/BufferingAppender.java

@@ -58,7 +58,7 @@
  * <h3>Configuration Example:</h3>
  * <pre>{@code
  * <BufferingAppender name="BufferedAppender" 
- *                    bufferAtVerbosity="INFO" 
+ *                    bufferAtVerbosity="DEBUG" 
  *                    maxBytes="20480" 
  *                    flushOnErrorLog="true">
  *   <AppenderRef ref="ConsoleAppender"/>
@@ -80,7 +80,7 @@
  *   <li>On Lambda completion: remaining buffered logs can be flushed via {@link software.amazon.lambda.powertools.logging.PowertoolsLogging}</li>
  * </ul>
  * 
- * @see software.amazon.lambda.powertools.logging.PowertoolsLogging#flushLogBuffer()
+ * @see software.amazon.lambda.powertools.logging.PowertoolsLogging#flushBuffer()
  */
 @Plugin(name = BUFFERING_APPENDER_PLUGIN_NAME, category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE)
 public class BufferingAppender extends AbstractAppender implements BufferManager {

powertools-logging/powertools-logging-log4j/src/test/java/software/amazon/lambda/powertools/logging/log4j/internal/Log4jLoggingManagerTest.java

@@ -1,6 +1,7 @@
 package software.amazon.lambda.powertools.logging.log4j.internal;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.contentOf;
 import static org.slf4j.event.Level.DEBUG;
 import static org.slf4j.event.Level.ERROR;
 import static org.slf4j.event.Level.WARN;
@@ -92,6 +93,9 @@ void shouldDetectMultipleBufferingAppendersRegardlessOfName() throws IOException
         // Then - both appenders should have flushed their buffers
         File logFile = new File("target/logfile.json");
         assertThat(logFile).exists();
+        assertThat(contentOf(logFile))
+                .contains("Test message 1")
+                .contains("Test message 2");
     }
 
     @AfterEach