Index: trunk/test/unit/org/openstreetmap/josm/data/osm/BBoxTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/osm/BBoxTest.java	(revision 17749)
+++ trunk/test/unit/org/openstreetmap/josm/data/osm/BBoxTest.java	(revision 17752)
@@ -4,4 +4,5 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -34,7 +35,26 @@
     void testEqualsContract() {
         TestUtils.assumeWorkingEqualsVerifier();
-        EqualsVerifier.forClass(BBox.class).usingGetClass()
+        EqualsVerifier.forClass(BBox.class)
             .suppress(Warning.NONFINAL_FIELDS)
             .verify();
+    }
+
+    /**
+     * Unit test of {@link BBox#equals} method.
+     */
+    @Test
+    void testEquals() {
+        BBox box = new BBox(1, 2, 3, 4);
+        assertEquals(box, box);
+        assertEquals(box, new BBox(box));
+        assertEquals(box, box.toImmutable());
+    }
+
+    /**
+     * Unit test of {@link BBox#toImmutable} method.
+     */
+    @Test
+    void testToImmutable() {
+        assertThrows(UnsupportedOperationException.class, () -> new BBox(1, 2, 3, 4).toImmutable().add(5, 6));
     }