[Test] cover both python and cpp mode for largefifo_rtlsim

tests/fpgadataflow/test_fifosizing.py

@@ -49,14 +49,19 @@ def fetch_test_model(topology, wbits=2, abits=2):
 
 @pytest.mark.slow
 @pytest.mark.vivado
-@pytest.mark.parametrize("method", ["largefifo_rtlsim", "characterize"])
+@pytest.mark.parametrize(
+    "method", ["largefifo_rtlsim_python", "largefifo_rtlsim_cpp", "characterize"]
+)
 def test_fifosizing_linear(method):
+    force_python_rtlsim = "python" in method
+    method_key = "largefifo_rtlsim" if "largefifo_rtlsim" in method else "characterize"
     tmp_output_dir = fetch_test_model("tfc")
     cfg = build_cfg.DataflowBuildConfig(
         output_dir=tmp_output_dir,
         auto_fifo_depths=True,
-        auto_fifo_strategy=method,
+        auto_fifo_strategy=method_key,
         target_fps=10000,
+        force_python_rtlsim=force_python_rtlsim,
         synth_clk_period_ns=10.0,
         board="Pynq-Z1",
         rtlsim_batch_size=100,