### Question:
DefaultGroupExtractor implements GroupExtractor { public String getGroupName(final HttpServletRequest request) { Validate.notNull(request); String uri = request.getRequestURI(); final String includeUriPath = (String) request.getAttribute(ATTR_INCLUDE_PATH); uri = includeUriPath != null ? includeUriPath : uri; final String groupName = FilenameUtils.getBaseName(stripSessionID(uri)); return StringUtils.isEmpty(groupName) ? null : groupName; }  String getGroupName(final HttpServletRequest request); ResourceType getResourceType(final HttpServletRequest request); String encodeGroupUrl(final String groupName, final ResourceType resourceType, final boolean minimize); boolean isMinimized(final HttpServletRequest request); static final String ATTR_INCLUDE_PATH; static final String PARAM_MINIMIZE; }### Answer:
@Test(expected = NullPointerException.class) public void cannotExtractGroupNameWithNullUri() { groupExtractor.getGroupName(null); }