IOKit: Make assumptions of test explicit, so that test is skipped and…

… not marked as failed

contrib/platform/test/com/sun/jna/platform/mac/IOKitTest.java

@@ -30,6 +30,7 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -166,8 +167,12 @@ public void testIteratorParentChild() {
 
             // Get device name
             String controllerName = controllerDevice.getName();
+            assertNotNull(controllerName);
             // Root controllers always begin with "AppleUSB"
-            assertEquals("AppleUSB", controllerName.substring(0, 8));
+            assumeTrue(
+                    "Expected USB controller not found (controllerName should start with AppleUSB)",
+                    controllerName.startsWith("AppleUSB")
+            );
 
             // Get the first child, to test vs. iterator
             boolean testFirstChild = true;