### Question:
CustomBaseUrlArchive extends AbstractArchive { @Override public String getExtension() { return delegate.getExtension(); } CustomBaseUrlArchive(Archive delegate, String baseUrl); @Override String getExtension(); @Override String getArchiveName(); @Override String getPathToExecutable(); @Override String getVersion(); @Override String getClassifier();  }### Answer:
@Test public void testGetExtension() { when(delegate.getExtension()).thenReturn(EXTENSION); assertThat(archive.getExtension()).isEqualTo(EXTENSION); }