### Question:
ReaperMonitor { public double getRateOfDeletion() { if (reaperRuns.isEmpty()) { return 0D; } double numDeletedSessions = 0D; for (ReaperRun reaperRun : reaperRuns) { numDeletedSessions += reaperRun.getNumberOfDeletedSessions(); } return numDeletedSessions / reaperRuns.size(); }  void add(final long startTime, final long runTime, final long numberOfDeletedSessions); double getRateOfDeletion();  }### Answer:
@Test public void shouldGetZeroWhenNoRunsAdded() { double result = reaperMonitor.getRateOfDeletion(); assertEquals(result, 0D); }