Index: src/main/java/org/apache/jackrabbit/test/api/observation/AddEventListenerTest.java
===================================================================
--- src/main/java/org/apache/jackrabbit/test/api/observation/AddEventListenerTest.java	(revision 508386)
+++ src/main/java/org/apache/jackrabbit/test/api/observation/AddEventListenerTest.java	(working copy)
@@ -191,6 +191,8 @@
         Node n = testRootNode.addNode(nodeName, nodeType);
         if (!n.isNodeType(mixReferenceable)) {
             n.addMixin(mixReferenceable);
+            // some implementations may require a save after addMixin()
+            testRootNode.save();
         }
         return n;
     }
Index: src/main/java/org/apache/jackrabbit/test/api/SetPropertyAssumeTypeTest.java
===================================================================
--- src/main/java/org/apache/jackrabbit/test/api/SetPropertyAssumeTypeTest.java	(revision 508386)
+++ src/main/java/org/apache/jackrabbit/test/api/SetPropertyAssumeTypeTest.java	(working copy)
@@ -352,6 +352,8 @@
 
         Node referenceableNode = testRootNode.addNode(nodeName2);
         referenceableNode.addMixin(mixReferenceable);
+        // some implementations may require a save after addMixin()
+        testRootNode.save();
 
         Property prop = testNode.setProperty(testPropName, referenceableNode);
         assertEquals("setProperty(String, Value) of a property of type undefined " +
Index: src/main/java/org/apache/jackrabbit/test/api/SetValueConstraintViolationExceptionTest.java
===================================================================
--- src/main/java/org/apache/jackrabbit/test/api/SetValueConstraintViolationExceptionTest.java	(revision 508386)
+++ src/main/java/org/apache/jackrabbit/test/api/SetValueConstraintViolationExceptionTest.java	(working copy)
@@ -448,6 +448,9 @@
             nodeNotSatisfied = testRootNode.addNode(nodeName4, nodeTypeNotSatisfied);
             nodeNotSatisfied.addMixin(mixReferenceable);
 
+            // some implementations may require a save after addMixin()
+            testRootNode.save();
+
             prop = node.setProperty(propDef.getName(), nodeSatisfied);
             testRootNode.save();
         } catch (ConstraintViolationException e) {
@@ -812,12 +815,15 @@
             // create a referenceable node satisfying the constraint
             nodeSatisfied = testRootNode.addNode(nodeName3, nodeTypeSatisfied);
             nodeSatisfied.addMixin(mixReferenceable);
-            Value valueSatisfied = superuser.getValueFactory().createValue(nodeSatisfied);
 
             // create a referenceable node not satisfying the constraint
             nodeNotSatisfied = testRootNode.addNode(nodeName4, nodeTypeNotSatisfied);
             nodeNotSatisfied.addMixin(mixReferenceable);
+            
+            // some implementations may require a save after addMixin()
+            testRootNode.save();
 
+            Value valueSatisfied = superuser.getValueFactory().createValue(nodeSatisfied);
             prop = node.setProperty(propDef.getName(), new Value[]{valueSatisfied});
             testRootNode.save();
         } catch (ConstraintViolationException e) {
Index: src/main/java/org/apache/jackrabbit/test/api/SetValueValueFormatExceptionTest.java
===================================================================
--- src/main/java/org/apache/jackrabbit/test/api/SetValueValueFormatExceptionTest.java	(revision 508386)
+++ src/main/java/org/apache/jackrabbit/test/api/SetValueValueFormatExceptionTest.java	(working copy)
@@ -212,6 +212,8 @@
         try {
             Node referenceableNode = testRootNode.addNode(nodeName3);
             referenceableNode.addMixin(mixReferenceable);
+            // some implementations may require a save after addMixin()
+            testRootNode.save();
 
             booleanProperty.setValue(referenceableNode);
             fail("Property.setValue(Node) must throw a ValueFormatException " +
@@ -261,6 +263,8 @@
                 throw new NotExecutableException(testNodeType + " does not support adding of mix:referenceable");
             } else {
                 n.addMixin(mixReferenceable);
+                // some implementations may require a save after addMixin()
+                testRootNode.save();
             }
         }
 
Index: src/main/java/org/apache/jackrabbit/test/api/TreeComparator.java
===================================================================
--- src/main/java/org/apache/jackrabbit/test/api/TreeComparator.java	(revision 508386)
+++ src/main/java/org/apache/jackrabbit/test/api/TreeComparator.java	(working copy)
@@ -234,7 +234,10 @@
             // the UUID during serialization.
             if (!referenceable.isNodeType(mixReferenceable)) {
                 referenceable.addMixin(mixReferenceable);
+                // some implementations may require a save after addMixin()                
+                session.save();
             }
+
             pt.setProperty(sc.referenceTestProperty, referenceable);
 
             // Create a boolean property on the root node, so I can test noRecurse and skipBinary at the same time