here's a failing test (here simply copied from a bunch of selection-related tests in my github, just add to your own test - tableView with 5 items and everything in default state :-)

    @Test
    public void testClearSelectionAtIndex() {
        int index = 2;
        getSelectionModel().select(index);
        getSelectionModel().clearSelection(index);
        assertTrue("selection must be empty after unselect the selected",
                getSelectionModel().isEmpty());
        assertFalse("index must be unselected", getSelectionModel().isSelected(index));
        assertEquals("index must be cleared",
                -1, getSelectionModel().getSelectedIndex());
    }

it fails (for both single and multiple selectionMode) at the last assert, somehow the selectedIndex property doesn't seem to get updated.