### Question:
Perforce implements SourceCodeManagementSystem { @Override public String getId() { return "p4"; } Perforce();  Perforce(OperatingSystem operatingSystem); @Override String getId(); @Override void prepareForUpdate(File file); @Override void prepareForDelete(File file);  }### Answer:
@Test public void returnsId() { assertEquals("ID", "p4", p4.getId()); }