### Question:
VFS { public static VFS getInstance() { return VFSHolder.INSTANCE; }  static VFS getInstance(); static void addImplClass(Class<? extends VFS> clazz); abstract boolean isValid(); List<String> list(String path); static final Class<?>[] IMPLEMENTATIONS; static final List<Class<? extends VFS>> USER_IMPLEMENTATIONS; }### Answer:
@Test public void getInstanceShouldNotBeNull() throws Exception { VFS vsf = VFS.getInstance(); Assert.assertNotNull(vsf); }
@Test void getInstanceShouldNotBeNull() { VFS vsf = VFS.getInstance(); Assertions.assertNotNull(vsf); }