How to properly extend a test case from different parents

UVM
,
1

I am trying to figure out what is the correct way of achieving the following objective with the use of inheritance.

base_test extends uvm_test

dut1_base_test extends base_test

dut2_base_test extends base_test

my_test extends (sometimes dut1_base_test, sometimes dut2_base_test). ← how do I do this?

dut1_base_test and dut2_base test have all the same tasks and function, but the tasks/function implementation is different. base_test also has all the same tasks and functions with empty implementations.

How do I programmatically tell my_test to extend from base_test1 or base_test2? The test does not need to change, only the underlying implementations of its tasks and functions.

the goal is that sometimes my_test will run against dut1 and sometimes against dut2. Dut1 and Dut2 look the same from the outside (same I/o) and are picked based on a verilog configuration/libmap.

I can’t quite wrap my head around class overriding as we have a chain of inheritance. if my_test extends base_test and then I override base_test to dut1_base_test, then it would seem like dut1_base_test now extends itself, as it’s parent has been overridden.

at this stage everything works if I only change the code from “extends dut1_base_test” to extends “dut2_base_test”. But obviously I do not want to change the code every time I want to do this. is there a way to do this right with factory overrides?

Appreciate any help on how to approach this correctly.

2

The SystemVerilog way of doing this is with a parameterized class.

class my_test #(type base) extends base;
  `uvm_component_param_utils(my_test_dut1)

endclass

However, the UVM factory requires a fixed string to be registered with the factory for the top level test, involving an additional extension.

class my_test_dut1 extends my_test#(dut1_base_test);
  `uvm_component_utils(my_test_dut1)
 
endclass
class my_test_dut2 extends my_test#(dut2_base_test);
  `uvm_component_utils(my_test_dut2)
 
endclass

I also might suggest looking at the decorator design pattern.