Mockito: Mock a JspWriter

MockAJspWriter.java

StringBuilder buffer = new StringBuilder();
JspWriter jspWriterMock = mock(JspWriter.class);  
Answer<JspWriter> answer = new Answer<JspWriter>() {  
 @Override  
 public JspWriter answer(final InvocationOnMock theInvocation) throws Throwable {  
  Method method = theInvocation.getMethod();  
  Method methodImpl = StringBuilder.class.getMethod(method.getName(), method.getParameterTypes());  
  methodImpl.invoke(buffer, theInvocation.getArguments());  
  return (JspWriter) theInvocation.getMock();  
 }  
};  
Answer<Void> answerB = new Answer<Void>() {  
 @Override  
 public Void answer(final InvocationOnMock theInvocation) throws Throwable {  
  buffer.append(theInvocation.getArguments()[0]);  
  return null;  
 }  
};  
when(jspWriterMock.append(Matchers.anyChar())).thenAnswer(answer);  
when(jspWriterMock.append(Matchers.anyString())).thenAnswer(answer);  
when(jspWriterMock.append(Matchers.anyString(),Matchers.anyInt(),Matchers.anyInt())).thenAnswer(answer);  
doAnswer(answerB).when(jspWriterMock).write(Matchers.anyString());  
doAnswer(answerB).when(jspWriterMock).write((char[])Matchers.anyVararg());  
doAnswer(answerB).when(jspWriterMock).write(Matchers.anyInt());