chore: import upstream snapshot with attribution

tests/fixtures/sample.sv

@@ -0,0 +1,44 @@
+package math_pkg;
+endpackage
+
+interface class Processor;
+endclass
+
+class BaseProcessor;
+endclass
+
+class Payload;
+endclass
+
+class Config;
+endclass
+
+class Result #(type T = Payload);
+  T value;
+endclass
+
+class DataProcessor extends BaseProcessor implements Processor;
+  Result #(Payload) current;
+  rand Config m_cfg;
+  protected BaseProcessor m_parent;
+
+  function Result #(Payload) build(Payload input);
+    return current;
+  endfunction
+endclass
+
+module leaf;
+endmodule
+
+module top;
+  import math_pkg::*;
+
+  function int add(input int a, input int b);
+    return a + b;
+  endfunction
+
+  task tick;
+  endtask
+
+  leaf u_leaf();
+endmodule