Refactor log4j-slf4j2-impl tests to use assertInstanceOf

Author: AlbaHerrerias

log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/Log4j1222Test.java

@@ -16,7 +16,7 @@
  */
 package org.apache.logging.slf4j;
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
@@ -47,8 +47,9 @@ public void run() {
 
         private void trigger() {
             Holder.LOGGER.info("Attempt to trigger");
-            assertTrue(
-                    Holder.LOGGER instanceof Log4jLogger,
+            assertInstanceOf(
+                    Log4jLogger.class,
+                    Holder.LOGGER,
                     "Logger is of type " + Holder.LOGGER.getClass().getName());
         }
     }

log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/LoggerContextTest.java

@@ -16,6 +16,7 @@
  */
 package org.apache.logging.slf4j;
 
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Set;
@@ -35,7 +36,7 @@ public void testCleanup() throws Exception {
         factory.getLogger("test");
         Set<LoggerContext> set = factory.getLoggerContexts();
         final LoggerContext ctx1 = set.toArray(LoggerContext.EMPTY_ARRAY)[0];
-        assertTrue(ctx1 instanceof LifeCycle, "LoggerContext is not enabled for shutdown");
+        assertInstanceOf(LifeCycle.class, ctx1, "LoggerContext is not enabled for shutdown");
         ((LifeCycle) ctx1).stop();
         set = factory.getLoggerContexts();
         assertTrue(set.isEmpty(), "Expected no LoggerContexts");

log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/MarkerTest.java

@@ -18,6 +18,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
@@ -59,7 +60,7 @@ public void testAddMarker() {
         final Marker log4jParent = MarkerManager.getMarker(parentMarkerName);
         final Marker log4jMarker = MarkerManager.getMarker(childMakerName);
 
-        assertTrue(slf4jMarker instanceof Log4jMarker, "Incorrect Marker class");
+        assertInstanceOf(Log4jMarker.class, slf4jMarker, "Incorrect Marker class");
         assertTrue(
                 log4jMarker.isInstanceOf(log4jParent),
                 String.format(