@Test public void testToFnWithContext() throws Exception { CombineFnWithContext<Integer, int[], Integer> fnWithContext = CombineFnUtil.toFnWithContext(Sum.ofIntegers()); List<Integer> inputs = ImmutableList.of(1, 2, 3, 4); Context nullContext = CombineContextFactory.nullContext(); int[] accum = fnWithContext.createAccumulator(nullContext); for (Integer i : inputs) { accum = fnWithContext.addInput(accum, i, nullContext); } assertEquals(10, fnWithContext.extractOutput(accum, nullContext).intValue()); } }