Fail the contention test when the two writers never collided: it would prove nothing (the review of 2026-10-10)

node-tools/internal/runtime/state_counter_test.go

@@ -122,6 +122,9 @@ func TestTwoWritersIncrementingOneCounterOnTheBusLoseNoUpdate(t *testing.T) {
 	if string(e.Value) != "2000" || len(seen) != 2*each {
 		t.Fatalf("the counter ended at %s with %d numbers handed out, not 2000: an increment was lost", e.Value, len(seen))
 	}
+	if lost[0]+lost[1] == 0 {
+		t.Fatal("the two writers never collided: the test proved nothing about contention")
+	}
 	t.Logf("2000 increments, %d writes lost to the other writer and tried again", lost[0]+lost[1])
 }