### Question:
DelegateIncrementalFileMergerOutput implements IncrementalFileMergerOutput { @Override public void update( @NonNull String path, @NonNull List<String> prevInputNames, @NonNull List<IncrementalFileMergerInput> inputs) { delegate.update(path, prevInputNames, inputs); } DelegateIncrementalFileMergerOutput(@NonNull IncrementalFileMergerOutput delegate); @Override void open(); @Override void close(); @Override void remove(@NonNull String path); @Override void create(@NonNull String path, @NonNull List<IncrementalFileMergerInput> inputs); @Override void update(
            @NonNull String path,
            @NonNull List<String> prevInputNames,
            @NonNull List<IncrementalFileMergerInput> inputs);  }### Answer:
@Test public void update() { ImmutableList<String> prevNames = ImmutableList.of(); ImmutableList<IncrementalFileMergerInput> inputs = ImmutableList.of(); delegate.update("foo", prevNames, inputs); Mockito.verify(mockOutput).update( Matchers.eq("foo"), Matchers.same(prevNames), Matchers.same(inputs)); }