### Question:
Nexus extends HorizontalTrack { @Override public boolean allowsConnection(Direction direction) { return !Direction.TOP.equals(direction); } Nexus(NexusContext context); @Override boolean allowsConnection(Direction direction); @Override boolean accepts(Direction direction, Marble marble); NexusContext getContext();  }### Answer:
@Test public void allowsConnectionLeft() { assertThat(nexus.allowsConnection(Direction.LEFT)).isTrue(); }
@Test public void allowsConnectionRight() { assertThat(nexus.allowsConnection(Direction.RIGHT)).isTrue(); }
@Test public void allowsConnectionBottom() { assertThat(nexus.allowsConnection(Direction.BOTTOM)).isTrue(); }
@Test public void disallowsConnectionTop() { assertThat(nexus.allowsConnection(Direction.TOP)).isFalse(); }