--- old/test/jdk/java/foreign/TestByteBuffer.java	2020-04-30 16:04:05.000000000 +0100
+++ new/test/jdk/java/foreign/TestByteBuffer.java	2020-04-30 16:04:05.000000000 +0100
@@ -78,7 +78,7 @@
 import org.testng.SkipException;
 import org.testng.annotations.*;
 import sun.nio.ch.DirectBuffer;
-
+import static jdk.incubator.foreign.MemorySegment.*;
 import static org.testng.Assert.*;
 
 public class TestByteBuffer {
@@ -236,6 +236,21 @@
         }
     }
 
+    static final int ALL_ACCESS_MODES = READ | WRITE | CLOSE | ACQUIRE | HANDOFF;
+
+    @Test
+    public void testDefaultAccessModesMappedSegment() throws Throwable {
+        try (MappedMemorySegment segment = MemorySegment.mapFromPath(tempPath, 8, FileChannel.MapMode.READ_WRITE)) {
+            assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES));
+            assertEquals(segment.accessModes(), ALL_ACCESS_MODES);
+        }
+
+        try (MappedMemorySegment segment = MemorySegment.mapFromPath(tempPath, 8, FileChannel.MapMode.READ_ONLY)) {
+            assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES & ~WRITE));
+            assertEquals(segment.accessModes(), ALL_ACCESS_MODES& ~WRITE);
+        }
+    }
+
     @Test
     public void testMappedSegment() throws Throwable {
         File f = new File("test2.out");
@@ -446,6 +461,21 @@
         }
     }
 
+    @Test
+    public void testDefaultAccessModesOfBuffer() {
+        ByteBuffer rwBuffer = ByteBuffer.wrap(new byte[4]);
+        try (MemorySegment segment = MemorySegment.ofByteBuffer(rwBuffer)) {
+            assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES));
+            assertEquals(segment.accessModes(), ALL_ACCESS_MODES);
+        }
+
+        ByteBuffer roBuffer = rwBuffer.asReadOnlyBuffer();
+        try (MemorySegment segment = MemorySegment.ofByteBuffer(roBuffer)) {
+            assertTrue(segment.hasAccessModes(ALL_ACCESS_MODES & ~WRITE));
+            assertEquals(segment.accessModes(), ALL_ACCESS_MODES & ~WRITE);
+        }
+    }
+
     @Test(dataProvider="bufferSources")
     public void testBufferToSegment(ByteBuffer bb, Predicate<MemorySegment> segmentChecker) {
         MemorySegment segment = MemorySegment.ofByteBuffer(bb);