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Am I done testing yet? A (fun!) coverage question..

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I want to verify the following behavior:

"DUT shall only accept command A, and reject all others while in the Powerup state.  While not in Powerup, accept all commands"

This is the state of the DUT following a reset.


Option 1 - No covergroup

After a reset, send all commands that are NOT A, followed by command A.  If the scoreboard doesn't fail, then I'm good to go.


Option 2 - Covergroup

Have a monitor hanging off an agent that, when it detects a command is written, it crossed the state of the DUT with the command being written.


With option 1, I have no coverage metric that the test was even performed.  However, I can very quickly write a test, and it doesn't require any components.  The integrity of the test is paramount here.

With option 2, I've got to use a bound virtual interface to access the state bits of the DUT, and also build a coverage collector.



My heart wants to simply define my coverage model entirely via covergroups, and then generate stimuli until I meet 100%.

My brain, however, says no, no...  don't verify that you sent the sequence Cmd A -> Cmd C -> Cmd E -> Cmd A, just write a directed test that does that.



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