First,let's have a look at Salesforce API about adderror:
addError(errorMsg)
Marks a record with a custom error message and prevents any DML operation from occurring.
Notice that the first word is 'Marks', means this function will not stop any script.
I wrote a trigger for test this.
trigger testAddError on Account (before update) {
integer i = 0;
for(Account a :trigger.New){
system.debug('before test error'+ i);
if(i == 0)
a.name.adderror('testError' + i);
system.debug('after test error'+ i);
i++;
}
}
then I update a Account. here is the log
12:57:24:091 USER_DEBUG [4]|DEBUG|before test error0 12:57:24:091 USER_DEBUG [7]|DEBUG|after test error0