Evaluator tests: fix issue with replay buffer path

tests/gflownet/evaluator/test_base.py

@@ -221,7 +221,7 @@ def test__should_eval_top_k(constant_evaluator, period, step, target, first_it,
     ],
 )
 def test__eval(gflownet_for_tests, parameterization):
-    assert Path("./replay.pkl").exists()
+    assert gflownet_for_tests.buffer.replay_pkl.exists()
     # results: {"metrics": dict[str, float], "figs": list[plt.Figure]}
     results = gflownet_for_tests.evaluator.eval()
     figs = gflownet_for_tests.evaluator.plot(**results["data"])