Index: modules/pvm/src/main/java/org/jbpm/pvm/internal/history/model/HistoryTaskImpl.java
===================================================================
--- modules/pvm/src/main/java/org/jbpm/pvm/internal/history/model/HistoryTaskImpl.java	(revision 6315)
+++ modules/pvm/src/main/java/org/jbpm/pvm/internal/history/model/HistoryTaskImpl.java	(working copy)
@@ -97,6 +97,7 @@
   
   public void addDetail(HistoryDetailImpl detail) {
     detail.setHistoryTask(this, nextDetailIndex);
+    this.details.add(detail);
     nextDetailIndex++;
   }
 
Index: modules/test-db/src/test/java/org/jbpm/test/history/HistoryTaskDetailTest.java
===================================================================
--- modules/test-db/src/test/java/org/jbpm/test/history/HistoryTaskDetailTest.java	(revision 0)
+++ modules/test-db/src/test/java/org/jbpm/test/history/HistoryTaskDetailTest.java	(revision 0)
@@ -0,0 +1,136 @@
+/*
+ * JBoss, Home of Professional Open Source
+ * Copyright 2005, JBoss Inc., and individual contributors as indicated
+ * by the @authors tag. See the copyright.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.jbpm.test.history;
+
+import java.util.Date;
+import java.util.List;
+import org.jbpm.api.cmd.Command;
+import org.jbpm.api.cmd.Environment;
+import org.jbpm.api.history.HistoryActivityInstance;
+import org.jbpm.api.task.Task;
+import org.jbpm.test.JbpmTestCase;
+
+
+/**
+ * @author Huisheng Xu
+ */
+public class HistoryTaskDetailTest extends JbpmTestCase {
+  private static final String PROCESS_XML =
+      "<process name='HistoryTaskDetail'>" +
+      "  <start>" +
+      "    <transition to='review' />" +
+      "  </start>" +
+      "  <task name='review' " +
+      "        assignee='johndoe'>" +
+      "    <transition to='wait' />" +
+      "  </task>" +
+      "  <state name='wait'/>" +
+      "</process>";
+
+  protected void setUp() throws Exception {
+    super.setUp();
+    deployJpdlXmlString(PROCESS_XML);
+  }
+
+  public void testHistoryAssignment() {
+    executionService.startProcessInstanceByKey("HistoryTaskDetail");
+
+    List<Task> tasks = taskService.findPersonalTasks("johndoe");
+    assertEquals(1, tasks.size());
+    String taskId = tasks.get(0).getId();
+    processEngine.execute(new TaskReassignCmd(taskId, "Lingo"));
+
+    assertEquals(1, taskService.findPersonalTasks("Lingo").size());
+    assertEquals(1, historyService.createHistoryDetailQuery().list().size());
+  }
+
+  public void testHistoryPriority() {
+    executionService.startProcessInstanceByKey("HistoryTaskDetail");
+
+    List<Task> tasks = taskService.findPersonalTasks("johndoe");
+    assertEquals(1, tasks.size());
+    String taskId = tasks.get(0).getId();
+    processEngine.execute(new TaskChangePriorityCmd(taskId, 10));
+
+    assertEquals(1, historyService.createHistoryDetailQuery().list().size());
+  }
+
+  public void testHistoryDuedate() {
+    executionService.startProcessInstanceByKey("HistoryTaskDetail");
+
+    List<Task> tasks = taskService.findPersonalTasks("johndoe");
+    assertEquals(1, tasks.size());
+    String taskId = tasks.get(0).getId();
+    processEngine.execute(new TaskChangeDuedateCmd(taskId, new Date()));
+
+    assertEquals(1, historyService.createHistoryDetailQuery().list().size());
+  }
+
+  static class TaskReassignCmd implements Command<Void> {
+    private String taskId;
+    private String newAssignee;
+    public TaskReassignCmd(String taskId, String newAssignee) {
+      this.taskId = taskId;
+      this.newAssignee = newAssignee;
+    }
+    public Void execute(Environment env) {
+      Task task = taskService.getTask(taskId);
+      task.setAssignee(newAssignee);
+      taskService.saveTask(task);
+
+      return null;
+    }
+  }
+
+  static class TaskChangePriorityCmd implements Command<Void> {
+    private String taskId;
+    private int newPriority;
+    public TaskChangePriorityCmd(String taskId, int newPriority) {
+      this.taskId = taskId;
+      this.newPriority = newPriority;
+    }
+    public Void execute(Environment env) {
+      Task task = taskService.getTask(taskId);
+      task.setPriority(newPriority);
+      taskService.saveTask(task);
+
+      return null;
+    }
+  }
+
+  static class TaskChangeDuedateCmd implements Command<Void> {
+    private String taskId;
+    private Date newDuedate;
+    public TaskChangeDuedateCmd(String taskId, Date newDuedate) {
+      this.taskId = taskId;
+      this.newDuedate = newDuedate;
+    }
+    public Void execute(Environment env) {
+      Task task = taskService.getTask(taskId);
+      task.setDuedate(newDuedate);
+      taskService.saveTask(task);
+
+      return null;
+    }
+  }
+
+}