请教一个easymock的问题

按照easymock的文档写了一个简单的例子,竟然报错:

import static org.easymock.EasyMock.*;
import junit.framework.TestCase;

public class ParserTest extends TestCase {
        private Parser parser;
        private SynFilter mock;
        private String text = "计算机";

        public static void main(String[] args) {
                junit.textui.TestRunner.run(ParserTest.class);
        }

        protected void setUp() throws Exception {
                super.setUp();
                mock = createMock(SynFilter.class);
                parser = new Parser();
                parser.setFilter(mock);
        }

        protected void tearDown() throws Exception {
                super.tearDown();
        }

        /*
         * Test method for 'Parser.parse(String)'
         */
        public void testParse() {
                mock.getSynonym("计算机");
                replay(mock);
                parser.parse("计算机");
                verify(mock);
        }

}


There was 1 error:
1) testParse(ParserTest)java.lang.IllegalStateException: missing behavior definition for the preceeding method call getSynonym("计算机")
        at org.easymock.internal.MocksControl.replay(MocksControl.java:61)
        at org.easymock.EasyMock.replay(EasyMock.java:1280)
        at ParserTest.testParse(ParserTest.java:29)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at ParserTest.main(ParserTest.java:10)