@Test
public void findSagaInstanceKey_readerForMessageNotPartOfSaga_returnsNull() {

    // given
    final String keyValue = "theKeyValue";
    KeyReader reader = FunctionKeyReader.create(Integer.class, new KeyReadFunction<Integer>() {
        @Override
        public String key(Integer intVal) {
            return keyValue;
        }
    });
    when(testSaga.keyReaders()).thenReturn(Lists.newArrayList(reader));
    // when
    Object foundKey = sut.findSagaInstanceKey(Saga.class, SagaLookupContext.forMessage("my input event message"));
    // then
    assertThat("Expected returned key to be null.", foundKey, nullValue());
}