### Question:
ELUtils { public static void buildFacesResolver(FacesCompositeELResolver composite, ApplicationAssociate associate) { checkNotNull(composite, associate); if (!tryAddCDIELResolver(composite)) { composite.addRootELResolver(IMPLICIT_RESOLVER); } composite.add(FLASH_RESOLVER); composite.addPropertyELResolver(COMPOSITE_COMPONENT_ATTRIBUTES_EL_RESOLVER); addELResolvers(composite, associate.getELResolversFromFacesConfig()); composite.add(associate.getApplicationELResolvers()); composite.addPropertyELResolver(RESOURCE_RESOLVER); composite.addPropertyELResolver(BUNDLE_RESOLVER); composite.addRootELResolver(FACES_BUNDLE_RESOLVER); addEL3_0_Resolvers(composite, associate); composite.addPropertyELResolver(MAP_RESOLVER); composite.addPropertyELResolver(LIST_RESOLVER); composite.addPropertyELResolver(ARRAY_RESOLVER); composite.addPropertyELResolver(BEAN_RESOLVER); composite.addRootELResolver(SCOPED_RESOLVER); } private  ELUtils(); static boolean isCompositeComponentExpr(String expression); static boolean isCompositeComponentMethodExprLookup(String expression); static boolean isCompositeComponentLookupWithArgs(String expression); static void buildFacesResolver(FacesCompositeELResolver composite, ApplicationAssociate associate); static Object evaluateValueExpression(ValueExpression expression, ELContext elContext); static ValueExpression createValueExpression(String expression, Class<?> expectedType); static boolean isScopeValid(String scopeName); static ExpressionFactory getDefaultExpressionFactory(FacesContext facesContext); static ExpressionFactory getDefaultExpressionFactory(ApplicationAssociate associate, FacesContext facesContext); static final ArrayELResolver ARRAY_RESOLVER; static final BeanELResolver BEAN_RESOLVER; static final FacesResourceBundleELResolver FACES_BUNDLE_RESOLVER; static final ImplicitObjectELResolver IMPLICIT_RESOLVER; static final FlashELResolver FLASH_RESOLVER; static final ListELResolver LIST_RESOLVER; static final MapELResolver MAP_RESOLVER; static final ResourceBundleELResolver BUNDLE_RESOLVER; static final ScopedAttributeELResolver SCOPED_RESOLVER; static final ResourceELResolver RESOURCE_RESOLVER; static final CompositeComponentAttributesELResolver COMPOSITE_COMPONENT_ATTRIBUTES_EL_RESOLVER; }### Answer:
@Test public void testNPEWhenStreamELResolverIsNull() { applicationAssociate.setExpressionFactory(new ExpressionFactoryImpl() { @Override public ELResolver getStreamELResolver() { return null; } }); DemuxCompositeELResolver elResolver = new DemuxCompositeELResolver(FacesCompositeELResolver.ELResolverChainType.Faces); ELUtils.buildFacesResolver(elResolver, applicationAssociate); }