diff --git a/jass/models/plots.py b/jass/models/plots.py
index 3953d0f3419db0e4bbebd31e675a7d54a0be2991..f00b5ad6904aab83cdd942ed1e4f954a9b6ad802 100644
--- a/jass/models/plots.py
+++ b/jass/models/plots.py
@@ -39,7 +39,7 @@ def create_global_plot(work_file_path: str, global_plot_path: str):
     """
 
     regions = read_hdf(work_file_path, "Regions")
-    chr_length = regions.groupby('CHR').max().position
+    #chr_length = regions.groupby('CHR').max().position
     N_reg= regions.Region.max()
     maxy = 0
 
diff --git a/jass/test/expected_graphs/expected_global_plot.png b/jass/test/expected_graphs/expected_global_plot.png
new file mode 100644
index 0000000000000000000000000000000000000000..a1896d6c7795ac13c1aa6e542cf41f7246e43a08
Binary files /dev/null and b/jass/test/expected_graphs/expected_global_plot.png differ
diff --git a/jass/test/test_plots.py b/jass/test/test_plots.py
index ad0012abe26c219928e091f836c1a26e87034b9f..390dbe614c8dbaabe1f5fbb9b6eda95b5902bb35 100644
--- a/jass/test/test_plots.py
+++ b/jass/test/test_plots.py
@@ -12,10 +12,12 @@ from . import JassTestCase
 class TestPlots(JassTestCase):
 
     test_folder = "data_real"
+    expected_res_folder = "expected_graphs"
 
     def setUp(self):
         # Create a temporary directory
         self.test_dir = Path(tempfile.mkdtemp())
+        self.ref_res_dir=Path(os.path.join(os.path.dirname(os.path.abspath(__file__)), self.expected_res_folder))
         self.worktable_hdf_path = self.get_file_path_fn("worktable-withnans.hdf5")
 
     def tearDown(self):
@@ -25,6 +27,15 @@ class TestPlots(JassTestCase):
 
     def test_create_global_plot(self):
         plots.create_global_plot(self.worktable_hdf_path, self.test_dir / "global_plot.png")
+        #plots.create_global_plot(self.worktable_hdf_path,  "/Users/vlegrand/tmp/global_plot.png")
+        fnew=open(self.test_dir / "global_plot.png",'rb')
+        fref=open(self.ref_res_dir / "expected_global_plot.png",'rb')
+        content_new=fnew.read()
+        content_ref=fref.read()
+        assert(content_new==content_ref)
+        fnew.close()
+        fref.close()
+
 
     def test_create_qq_plot(self):
         plots.create_qq_plot(self.worktable_hdf_path, self.test_dir / "qq_plot.png")