### Question:
WatchesPathReport { public Set<Long> getSessions(String path) { Set<Long> s = path2Ids.get(path); return s != null ? Collections.unmodifiableSet(s) : null; } WatchesPathReport(Map<String, Set<Long>> path2Ids); boolean hasSessions(String path); Set<Long> getSessions(String path); Map<String, Set<Long>> toMap();  }### Answer:
@Test public void testGetSessions() { Set<Long> s = r.getSessions("path1"); assertEquals(2, s.size()); assertTrue(s.contains(101L)); assertTrue(s.contains(102L)); s = r.getSessions("path2"); assertEquals(1, s.size()); assertTrue(s.contains(201L)); assertNull(r.getSessions("path3")); }