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