Add golden file and completing-attempt run to s_always liveness test

test_regress/t/t_prop_s_always_liveness.out

@@ -0,0 +1,4 @@
+*-* All Finished *-*
+[115] %Error: t_prop_s_always_liveness.v:28: Assertion failed in top.t
+%Error: t/t_prop_s_always_liveness.v:28: Verilog $stop
+Aborting...

test_regress/t/t_prop_s_always_liveness.py

@@ -12,6 +12,6 @@ import vltest_bootstrap
 test.scenarios('vlt')
 
 test.compile(verilator_flags2=['--assert'])
-test.execute(fails=True)
+test.execute(fails=True, expect_filename=test.golden_filename)
 
 test.passes()

test_regress/t/t_prop_s_always_liveness.v

@@ -15,24 +15,34 @@ module t (
 
   int cyc = 0;
   logic a_high = 1'b1;
-  logic a_low  = 1'b0;
+  logic a_low = 1'b0;
 
   int low_s_fail_q[$];
   int low_w_fail_q[$];
 
-  as_liveness: assert property (@(posedge clk) s_always [2:5] a_high);
-  as_weak: assert property (@(posedge clk) always [2:5] a_high);
+  // A new attempt starts every tick, so the last hi attempts still have an open
+  // [2:5] window when the trace ends. Even though a_high is constantly true,
+  // those unfinished attempts report a liveness failure; Verilator OR-reduces
+  // them into one end-of-simulation error. (Questa 2022.3: 6 earlier attempts
+  // complete, the 5 youngest fire the strong else at $finish.)
+  assert property (@(posedge clk) s_always [2:5] a_high);
+  // Weak always makes no end-of-trace obligation: silent.
+  assert property (@(posedge clk) always [2:5] a_high);
 
-  as_low_s: assert property (@(posedge clk) s_always [2:5] a_low)
-    ; else low_s_fail_q.push_back(cyc);
-  as_low_w: assert property (@(posedge clk) always [2:5] a_low)
-    ; else low_w_fail_q.push_back(cyc);
+  // Constant-false fails at the first window tick: a safety violation reported
+  // identically by weak and strong (the strong-only liveness affects just the
+  // still-open tail). Verilator counts 9 each at cyc 10. (Questa reads 8 -- a
+  // same-timestep else-vs-read ordering difference, not a semantic one.)
+  assert property (@(posedge clk) s_always [2:5] a_low)
+    else low_s_fail_q.push_back(cyc);
+  assert property (@(posedge clk) always [2:5] a_low)
+    else low_w_fail_q.push_back(cyc);
 
   always @(posedge clk) begin
     cyc <= cyc + 1;
-    if (cyc == 4) begin
-      `checkd(low_s_fail_q.size(), 3);
-      `checkd(low_w_fail_q.size(), 3);
+    if (cyc == 10) begin
+      `checkd(low_s_fail_q.size(), low_w_fail_q.size());
+      `checkd(low_w_fail_q.size(), 9);
       $write("*-* All Finished *-*\n");
       $finish;
     end