Review fixes for log4j-mdc-1.2:javaagent (#18196)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>
Co-authored-by: Lauri Tulmin <ltulmin@splunk.com>
Co-authored-by: Lauri Tulmin <tulmin@gmail.com>

Author: otelbot[bot]

instrumentation/log4j/log4j-mdc-1.2/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/log4j/mdc/v1_2/ListAppender.java

@@ -12,7 +12,7 @@
 
 public class ListAppender extends AppenderSkeleton {
 
-  private static final List<LoggingEvent> events = new ArrayList<LoggingEvent>();
+  private static final List<LoggingEvent> events = new ArrayList<>();
 
   @Override
   protected void append(LoggingEvent loggingEvent) {
@@ -27,11 +27,11 @@ public boolean requiresLayout() {
   @Override
   public void close() {}
 
-  public static void clearEvents() {
+  static void clearEvents() {
     events.clear();
   }
 
-  public static List<LoggingEvent> getEvents() {
+  static List<LoggingEvent> getEvents() {
     return events;
   }
 }

instrumentation/log4j/log4j-mdc-1.2/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/log4j/mdc/v1_2/Log4j1MdcTest.java

@@ -36,17 +36,20 @@ void noIdsWhenNoSpan() {
     logger.info("log message 2");
 
     List<LoggingEvent> events = ListAppender.getEvents();
+    assertThat(events)
+        .extracting(LoggingEvent::getMessage)
+        .containsExactly("log message 1", "log message 2");
 
-    assertThat(events).hasSize(2);
-    assertThat(events.get(0).getMessage()).isEqualTo("log message 1");
-    assertThat(events.get(0).getMDC("trace_id")).isNull();
-    assertThat(events.get(0).getMDC("span_id")).isNull();
-    assertThat(events.get(0).getMDC("trace_flags")).isNull();
+    LoggingEvent firstEvent = events.get(0);
+    LoggingEvent secondEvent = events.get(1);
 
-    assertThat(events.get(1).getMessage()).isEqualTo("log message 2");
-    assertThat(events.get(1).getMDC("trace_id")).isNull();
-    assertThat(events.get(1).getMDC("span_id")).isNull();
-    assertThat(events.get(1).getMDC("trace_flags")).isNull();
+    assertThat(firstEvent.getMDC("trace_id")).isNull();
+    assertThat(firstEvent.getMDC("span_id")).isNull();
+    assertThat(firstEvent.getMDC("trace_flags")).isNull();
+
+    assertThat(secondEvent.getMDC("trace_id")).isNull();
+    assertThat(secondEvent.getMDC("span_id")).isNull();
+    assertThat(secondEvent.getMDC("trace_flags")).isNull();
   }
 
   @Test
@@ -70,25 +73,28 @@ void idsWhenSpan() {
             });
 
     List<LoggingEvent> events = ListAppender.getEvents();
+    assertThat(events)
+        .extracting(LoggingEvent::getMessage)
+        .containsExactly("log message 1", "log message 2", "log message 3");
+
+    LoggingEvent firstEvent = events.get(0);
+    LoggingEvent secondEvent = events.get(1);
+    LoggingEvent thirdEvent = events.get(2);
 
-    assertThat(events).hasSize(3);
-    assertThat(events.get(0).getMessage()).isEqualTo("log message 1");
-    assertThat(events.get(0).getMDC("trace_id")).isEqualTo(span1.getSpanContext().getTraceId());
-    assertThat(events.get(0).getMDC("span_id")).isEqualTo(span1.getSpanContext().getSpanId());
-    assertThat(events.get(0).getMDC("trace_flags"))
+    assertThat(firstEvent.getMDC("trace_id")).isEqualTo(span1.getSpanContext().getTraceId());
+    assertThat(firstEvent.getMDC("span_id")).isEqualTo(span1.getSpanContext().getSpanId());
+    assertThat(firstEvent.getMDC("trace_flags"))
         .isEqualTo(span1.getSpanContext().getTraceFlags().asHex());
 
-    assertThat(events.get(1).getMessage()).isEqualTo("log message 2");
-    assertThat(events.get(1).getMDC("trace_id")).isNull();
-    assertThat(events.get(1).getMDC("span_id")).isNull();
-    assertThat(events.get(1).getMDC("trace_flags")).isNull();
+    assertThat(secondEvent.getMDC("trace_id")).isNull();
+    assertThat(secondEvent.getMDC("span_id")).isNull();
+    assertThat(secondEvent.getMDC("trace_flags")).isNull();
 
-    assertThat(events.get(2).getMessage()).isEqualTo("log message 3");
     // this explicit getMDCCopy() call here is to make sure that whole instrumentation is tested
-    events.get(2).getMDCCopy();
-    assertThat(events.get(2).getMDC("trace_id")).isEqualTo(span2.getSpanContext().getTraceId());
-    assertThat(events.get(2).getMDC("span_id")).isEqualTo(span2.getSpanContext().getSpanId());
-    assertThat(events.get(2).getMDC("trace_flags"))
+    thirdEvent.getMDCCopy();
+    assertThat(thirdEvent.getMDC("trace_id")).isEqualTo(span2.getSpanContext().getTraceId());
+    assertThat(thirdEvent.getMDC("span_id")).isEqualTo(span2.getSpanContext().getSpanId());
+    assertThat(thirdEvent.getMDC("trace_flags"))
         .isEqualTo(span2.getSpanContext().getTraceFlags().asHex());
   }
 
@@ -97,13 +103,13 @@ void resourceAttributes() {
     logger.info("log message 1");
 
     List<LoggingEvent> events = ListAppender.getEvents();
-
-    assertThat(events).hasSize(1);
-    assertThat(events.get(0).getMessage()).isEqualTo("log message 1");
-    assertThat(events.get(0).getMDC("trace_id")).isNull();
-    assertThat(events.get(0).getMDC("span_id")).isNull();
-    assertThat(events.get(0).getMDC("trace_flags")).isNull();
-    assertThat(events.get(0).getMDC("service.name")).isEqualTo("unknown_service:java");
-    assertThat(events.get(0).getMDC("telemetry.sdk.language")).isEqualTo("java");
+    assertThat(events).extracting(LoggingEvent::getMessage).containsExactly("log message 1");
+
+    LoggingEvent event = events.get(0);
+    assertThat(event.getMDC("trace_id")).isNull();
+    assertThat(event.getMDC("span_id")).isNull();
+    assertThat(event.getMDC("trace_flags")).isNull();
+    assertThat(event.getMDC("service.name")).isEqualTo("unknown_service:java");
+    assertThat(event.getMDC("telemetry.sdk.language")).isEqualTo("java");
   }
 }