diff --git a/tests/test_PostProcessing.py b/tests/test_PostProcessing.py
index 7009d6c6cfb42d3cf744c41e1f72102b6e58b10b..c94e587af3d692229d1318dd5294377087c9ac70 100644
--- a/tests/test_PostProcessing.py
+++ b/tests/test_PostProcessing.py
@@ -229,6 +229,25 @@ def test_check_reg_quality_pce(pce_engine) -> None:
 #%% _get_sample
 #%% _eval_model
 #%% _plot_validation
+def test_plot_validation(pce_engine) -> None:
+    """
+    Check the regression quality for PCE metamodel
+    """
+    engine = pce_engine
+    post = PostProcessing(engine)
+    post.pce_out_mean, post.pce_out_std = engine.eval_metamodel([[0],[0.5]])
+    post.model_out_dict = {'Z': [[0.4],[0.3]]}
+    post._plot_validation()
+
+def test_plot_validation(gpe_engine) -> None:
+    """
+    Check the regression quality for PCE metamodel
+    """
+    engine = pce_engine
+    post = PostProcessing(engine)
+    post.pce_out_mean, post.pce_out_std = engine.eval_metamodel([[0],[0.5]])
+    post.model_out_dict = {'Z': [[0.4],[0.3]]}
+    post._plot_validation()
 
 #%% _plot_validation_multi
     
\ No newline at end of file