when(delegate.getAttributes(toString, String.class)).thenReturn(attributes);
sources.add(delegate);
mds = new DelegatingMethodSecurityMetadataSource(sources);
assertSame(sources, mds.getMethodSecurityMetadataSources());
assertTrue(mds.getAllConfigAttributes().isEmpty());
MethodInvocation mi = new SimpleMethodInvocation("", toString);
assertSame(attributes, mds.getAttributes(mi));
// Exercise the cached case
assertSame(attributes, mds.getAttributes(mi));
assertTrue(mds.getAttributes(new SimpleMethodInvocation(null, String.class.getMethod("length"))).isEmpty());
}