### Question:
WrappedHttpServletResponse implements Response { @Override public void addHeader(String name, String value) { response.addHeader(name, value); } WrappedHttpServletResponse(HttpServletResponse response); @Override void resetCookie(String name, String path); @Override void setCookie(String name, String value, String path, String domain, int maxAge, boolean secure, boolean httpOnly); @Override void setStatus(int status); @Override void addHeader(String name, String value); @Override void setHeader(String name, String value); @Override OutputStream getOutputStream(); @Override void sendError(int code); @Override void sendError(int code, String message); @Override void end();  }### Answer:
@Test public void testAddHeader() throws Exception { String headerValue = "foo"; response.addHeader(HEADER, headerValue); verify(mockResponse).addHeader(eq(HEADER), eq(headerValue)); assertTrue(mockResponse.containsHeader(HEADER)); }