--- a/langtools/test/jdk/jshell/ReplToolTesting.java	Wed Mar 23 13:44:53 2016 +0100
+++ b/langtools/test/jdk/jshell/ReplToolTesting.java	Wed Mar 23 13:40:42 2016 +0100
@@ -33,6 +33,9 @@
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.prefs.AbstractPreferences;
+import java.util.prefs.BackingStoreException;
+import java.util.prefs.Preferences;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -41,6 +44,8 @@
 import jdk.internal.jshell.tool.JShellTool;
 import jdk.jshell.SourceCodeAnalysis.Suggestion;
 
+import org.testng.annotations.BeforeMethod;
+
 import static java.util.stream.Collectors.toList;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertNotNull;
@@ -83,6 +88,7 @@
     private Map<String, ClassInfo> classes;
     private Map<String, ImportInfo> imports;
     private boolean isDefaultStartUp = true;
+    private Preferences prefs;
 
     public JShellTool repl = null;
 
@@ -219,6 +225,11 @@
         }
     }
 
+    @BeforeMethod
+    public void setUp() {
+        prefs = new MemoryPreferences();
+    }
+
     public void testRaw(String[] args, ReplTest... tests) {
         cmdin = new WaitingTestingInputStream();
         cmdout = new ByteArrayOutputStream();
@@ -234,7 +245,8 @@
                 new PrintStream(console),
                 userin,
                 new PrintStream(userout),
-                new PrintStream(usererr));
+                new PrintStream(usererr),
+                prefs);
         repl.testPrompt = true;
         try {
             repl.start(args);
@@ -447,7 +459,7 @@
 
     private List<String> computeCompletions(String code, boolean isSmart) {
         JShellTool js = this.repl != null ? this.repl
-                                      : new JShellTool(null, null, null, null, null, null, null);
+                                      : new JShellTool(null, null, null, null, null, null, null, prefs);
         int cursor =  code.indexOf('|');
         code = code.replace("|", "");
         assertTrue(cursor > -1, "'|' not found: " + code);
@@ -762,4 +774,62 @@
             }
         }
     }
+
+    public static final class MemoryPreferences extends AbstractPreferences {
+
+        private final Map<String, String> values = new HashMap<>();
+        private final Map<String, MemoryPreferences> nodes = new HashMap<>();
+
+        public MemoryPreferences() {
+            this(null, "");
+        }
+
+        public MemoryPreferences(MemoryPreferences parent, String name) {
+            super(parent, name);
+        }
+
+        @Override
+        protected void putSpi(String key, String value) {
+            values.put(key, value);
+        }
+
+        @Override
+        protected String getSpi(String key) {
+            return values.get(key);
+        }
+
+        @Override
+        protected void removeSpi(String key) {
+            values.remove(key);
+        }
+
+        @Override
+        protected void removeNodeSpi() throws BackingStoreException {
+            ((MemoryPreferences) parent()).nodes.remove(name());
+        }
+
+        @Override
+        protected String[] keysSpi() throws BackingStoreException {
+            return values.keySet().toArray(new String[0]);
+        }
+
+        @Override
+        protected String[] childrenNamesSpi() throws BackingStoreException {
+            return nodes.keySet().toArray(new String[0]);
+        }
+
+        @Override
+        protected AbstractPreferences childSpi(String name) {
+            return nodes.computeIfAbsent(name, n -> new MemoryPreferences(this, name));
+        }
+
+        @Override
+        protected void syncSpi() throws BackingStoreException {
+        }
+
+        @Override
+        protected void flushSpi() throws BackingStoreException {
+        }
+
+    }
 }