+UVM_TESTNAME: Factory-Based Test Selection at Runtime

run_test() and factory selection

Calling run_test() without a string argument tells UVM to read +UVM_TESTNAME=<class_name> and construct that test type via the factory registry.

[TEST][UVM] selection flow

simv +UVM_TESTNAME=burst_traffic_test
        │
        ▼
run_test()  (no arg)
        │
        ▼
uvm_factory::create_component_by_name("burst_traffic_test", ...)
        │
        ▼
uvm_test_top = burst_traffic_test instance

// tb/top.sv — thin bridge, no hardcoded test name
initial begin
  uvm_config_db#(virtual axi_if)::set(null, "*", "vif", axi_vif);
  run_test();  // honors +UVM_TESTNAME from command line
end

# Regression selects scenario at runtime
./simv +UVM_TESTNAME=smoke_sanity_test
./simv +UVM_TESTNAME=protocol_illegal_len_test +ntb_random_seed=9001

Key takeaways

• One simv binary can run the entire test library via +UVM_TESTNAME.

• Factory registration (`uvm_component_utils) must include every runnable test.

• Top module should call run_test() — not run_test("hardcoded_name").

Common pitfalls

• Typo in test class name — factory error at runtime, not compile time.

• Forgetting to include new test files in the tests package.

• Mixing run_test("foo") in some builds and CLI selection in others.

Test registration and list hygiene

Test selection only works when every runnable test is compiled, registered, and named consistently.

Registration checklist

class smoke_sanity_test extends base_test;
  `uvm_component_utils(smoke_sanity_test)
  // ...
endclass

// tests_pkg must include the file:
`include "smoke/smoke_sanity_test.sv"

• Class name must match +UVM_TESTNAME exactly (case-sensitive).

• Use testlists (smoke.list, nightly.list) that reference class names.

• Keep a generated manifest in CI to catch missing registrations.

Explicit vs CLI selection

[TEST] when to pass run_test("name")

debug single test in IDE:
  run_test("repro_bug_441_test")  // OK for local debug

production / CI default:
  run_test()  // always prefer +UVM_TESTNAME

# testlist-driven loop
for t in $(cat nightly.list); do
  ./simv +UVM_TESTNAME=$t +ntb_random_seed=$RANDOM || exit 1
done

Common pitfalls

• Renaming test classes without updating testlists and dashboards.

• Runnable tests left out of package includes — silent omission from regressions.

• Using display names in scripts instead of exact SystemVerilog class names.