fix(diagrams): Set a dummy filename to prevent raise error when both name and filename are not provided(#203)

diagrams/__init__.py

@@ -101,8 +101,9 @@ class Diagram:
         :param edge_attr: Provide edge_attr dot config attributes.
         """
         self.name = name
-
-        if not filename:
+        if not name and not filename:
+          filename = "diagrams_file"
+        elif not filename:
             filename = "_".join(self.name.split()).lower()
         self.filename = filename
         self.dot = Digraph(self.name, filename=self.filename)

tests/test_diagram.py

@@ -100,6 +100,13 @@ class DiagramTest(unittest.TestCase):
             Node("node1")
         self.assertTrue(os.path.exists(f"{self.name}.png"))
 
+    def test_empty_name(self):
+      """Check that providing an empty name don't crash, but save in a diagrams_file.xxx file."""
+      self.name = 'diagrams_file'
+      with Diagram(show=False):
+          Node("node1")
+      self.assertTrue(os.path.exists(f"diagrams_file.png"))
+
 
 class ClusterTest(unittest.TestCase):
     def setUp(self):