Index: trunk/test/unit/org/openstreetmap/josm/gui/layer/MainLayerManagerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/layer/MainLayerManagerTest.java	(revision 18381)
+++ trunk/test/unit/org/openstreetmap/josm/gui/layer/MainLayerManagerTest.java	(revision 18393)
@@ -3,7 +3,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
-import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.Arrays;
@@ -17,4 +17,5 @@
 import org.openstreetmap.josm.gui.layer.MainLayerManager.ActiveLayerChangeListener;
 import org.openstreetmap.josm.gui.util.GuiHelper;
+import org.openstreetmap.josm.tools.Logging;
 
 /**
@@ -146,5 +147,7 @@
         CapturingActiveLayerChangeListener listener = new CapturingActiveLayerChangeListener();
         layerManagerWithActive.addActiveLayerChangeListener(listener);
-        assertThrows(IllegalArgumentException.class, () -> layerManagerWithActive.addActiveLayerChangeListener(listener));
+        Logging.clearLastErrorAndWarnings();
+        layerManagerWithActive.addActiveLayerChangeListener(listener);
+        assertFalse(Logging.getLastErrorAndWarnings().isEmpty());
     }
 
@@ -172,6 +175,7 @@
     @Test
     void testRemoveActiveLayerChangeListenerNotInList() {
-        assertThrows(IllegalArgumentException.class,
-                () -> layerManagerWithActive.removeActiveLayerChangeListener(new CapturingActiveLayerChangeListener()));
+        Logging.clearLastErrorAndWarnings();
+        layerManagerWithActive.removeActiveLayerChangeListener(new CapturingActiveLayerChangeListener());
+        assertFalse(Logging.getLastErrorAndWarnings().isEmpty());
     }