}
    }

    @Nested
    @DisplayName("Invalid and null inputs")
    class InvalidInputs {
        @Test
        @DisplayName("getSigningKey throws when unavailable")
        void testGetSigningKeyThrows() {
            DummySSPContext ctx = new DummySSPContext(null, false, null, null, 0, false);
            CIFSException ex = assertThrows(CIFSException.class, ctx::getSigningKey);