### Question:
ServletContextAttributeHelper { public static ServletContextAttributeHelper create(final FilterConfig filterConfig) { Validate.notNull(filterConfig); final String nameFromParam = filterConfig.getInitParameter(INIT_PARAM_NAME); final String name = nameFromParam != null ? nameFromParam : DEFAULT_NAME; return new ServletContextAttributeHelper(filterConfig.getServletContext(), name); } ServletContextAttributeHelper(final ServletContext servletContext);  ServletContextAttributeHelper(final ServletContext servletContext, final String name); static ServletContextAttributeHelper create(final FilterConfig filterConfig); WroManagerFactory getManagerFactory(); WroConfiguration getWroConfiguration(); void setWroConfiguration(final WroConfiguration config); void setManagerFactory(final WroManagerFactory managerFactory); void clear(); static final String DEFAULT_NAME; }### Answer:
@Test(expected = NullPointerException.class) public void cannotUseNullFilterConfig() { ServletContextAttributeHelper.create(null); }
@Test(expected = IllegalArgumentException.class) public void shouldFailWhenInitParamNameIsBlank() { Mockito.when(mockFilterConfig.getInitParameter(ServletContextAttributeHelper.INIT_PARAM_NAME)).thenReturn(" "); victim = ServletContextAttributeHelper.create(mockFilterConfig); }