Verifying Verification Components

[sas73]

What is the preferred way to verify that a verification component calls uvm_error when it's supposed to without that error causing an error for my test? I know about SVUnit and its mocking capabilities but is it a way to do this within UVM?

[David Black]

I would do something I've previously done with SystemC (where uvm_error hails from). Basically, replaced the report handler with my own intercept to recategorize errors. Then added a mechanism to register "expected" errors, warnings, fatals. Prior to a point where an error was going to be injected, I would issue something like:

begin_expect_error( "packet failure", 2 );
inject_error( ... );
wait_for_appropriate_time_or_event();
end_expect_error( "packet failure" );

If the report handler sees up to two errors, I would change the message severity to INFO and count off the expected error. At the end_expect_error call, I would check that exactly the number of expected errors occurred or consider it an error. Also, have to consider the possibility of the end_ call never happening.

[sas73]

Thanks for the reply David. This is similar do what has been done in SVUnit. They provide their own UVM reporter and redefine `uvm_error to call that instead. I was hoping that UVM already had a more built-in mechanism for intercepting messages. If so, I could simply put the intercepted messages in a queue, verify that the queue contains the messages I expect and then pass/fail the test accordingly. I have to dig deeper and learn more but I was hoping that there would be a UVM action I can use or maybe uvm_report_catcher which by the name of it sounds related. Maybe these concepts can't be used for what I'm trying to do? 

[kirloy369]

maybe uvm_report_catcher is what you need

http://www.vlsiencyclopedia.com/2016/10/build-smart-tests-using-uvm-report-catcher.html

[sas73]

Thanks @kirloy369! Looks more UVM idiomatic. Doesn't necessarily make it a better solution that what has been proposed before but I wanted to start by trying out how it was intended to be done.

[dave_59]

Give your error message a unique ID. Use  set_report_severity_id_override to change the severity of that ID from UVM_ERROR to UVM_INFO. Then call get_id_count at the end of your test to make sure it's non-zero. 

[sas73]

Thanks @dave_59. That would be the easiest way but in my case I want to verify that the message fields are what I expect, not only that a report has been produced. I ended up pushing the report message to a queue and then pop it in my test to verify the fields.

[David Black]

@kilroy369 I had forgotten that one. Much better suggestion. Same basic idea.