assertEquals(joinProbe.getChannelCount(), 1);
Block probeBlock = page.getBlock(0);
PageBuilder pageBuilder = new PageBuilder(ImmutableList.of(VARCHAR));
for (int position = 0; position < page.getPositionCount(); position++) {
assertTrue(joinProbe.advanceNextPosition());
joinProbe.appendTo(pageBuilder);
assertEquals(joinProbe.getCurrentJoinPosition(), lookupSource.getJoinPosition(position, probeBlock));
}