System.Savepoint sp = Database.setSavepoint();
try {
    //all you anonymous code
} catch(DmlException e) {
    System.debug('DmlException='+e);
} finally {
    Database.rollback(sp);
}

doStuffHere();
throw new NullPointerException();

$ force apex -test
>> Start typing Apex code; press CTRL-D(for Mac/Linux) / Ctrl-Z (for Windows) when finished
Test.startTest();
List<Account> accounts = [SELECT Id FROM Account];
System.assertEquals(3, accounts.size(), 'number of accounts');
Test.stopTest();

>> Executing code...
ERROR: System.AssertException: Assertion Failed: number of accounts: Expected: 3, Actual: 152
$ echo $?
1