Try alternative class loader.

hikaricp-java6/src/test/java/com/zaxxer/hikari/MiscTest.java

@@ -109,9 +109,8 @@ public class MiscTest
 
          Connection connection = ds.getConnection();
          PoolUtilities.quietlySleep(TimeUnit.SECONDS.toMillis(3));
-         ps.flush();
-         connection.close();
          ps.close();
+         connection.close();
          String s = new String(baos.toByteArray());
          Assert.assertTrue(s.contains("Connection leak detection"));
       }

hikaricp-java6/src/test/java/com/zaxxer/hikari/TestElf.java

@@ -77,7 +77,7 @@ public final class TestElf
    {
       SimpleLogger simpleLogger = (SimpleLogger) LoggerFactory.getLogger(clazz);
       try {
-         Field field = SimpleLogger.class.getDeclaredField("TARGET_STREAM");
+         Field field = clazz.getClassLoader().loadClass("org.slf4j.impl.SimpleLogger").getDeclaredField("TARGET_STREAM");
          field.setAccessible(true);
          field.set(simpleLogger, stream);
       }

hikaricp/src/test/java/com/zaxxer/hikari/MiscTest.java

@@ -109,9 +109,8 @@ public class MiscTest
 
          Connection connection = ds.getConnection();
          PoolUtilities.quietlySleep(TimeUnit.SECONDS.toMillis(3));
-         ps.flush();
-         connection.close();
          ps.close();
+         connection.close();
          String s = new String(baos.toByteArray());
          Assert.assertTrue(s.contains("Connection leak detection"));
       }

hikaricp/src/test/java/com/zaxxer/hikari/TestElf.java

@@ -77,7 +77,7 @@ public final class TestElf
    {
       SimpleLogger simpleLogger = (SimpleLogger) LoggerFactory.getLogger(clazz);
       try {
-         Field field = SimpleLogger.class.getDeclaredField("TARGET_STREAM");
+         Field field = clazz.getClassLoader().loadClass("org.slf4j.impl.SimpleLogger").getDeclaredField("TARGET_STREAM");
          field.setAccessible(true);
          field.set(simpleLogger, stream);
       }