diff --git a/seminar/tests_treelib.py b/seminar/tests_treelib.py
new file mode 100644
index 00000000..9c67ca22
--- /dev/null
+++ b/seminar/tests_treelib.py
@@ -0,0 +1,32 @@
+from django.test import TestCase
+import seminar.treelib as tl
+import seminar.models as m
+
+class SimpleTreeLibTests(TestCase):
+	def setUp(self):
+		# Vyrobíme pár nějakých Nodů
+		self.root = m.CastNode(root=None, first_child=None, succ=None, nadpis="Root")
+		self.root.save()
+		self.some_node = m.CastNode(root=self.root, first_child=None, succ=None, nadpis="Přetržené")
+		self.other_node = m.CastNode(root=self.root, first_child=None, succ=None, nadpis="Dítě")
+		self.some_orphan = m.CastNode(root=None, first_child=None, succ=None, nadpis="Ošklivé")
+		self.other_orphan = m.CastNode(root=None, first_child=None, succ=None, nadpis="Káčátko")
+		
+		# Trochu je pospojujeme
+		self.root.first_child = self.some_node
+		self.some_node.succ = self.other_node
+		self.some_orphan.first_child = self.other_orphan
+
+		# Všechno uložíme
+		self.other_node.save()
+		self.some_node.save()
+		self.other_orphan.save()
+		self.some_orphan.save()
+		self.root.save()
+	
+	def test_safe_functions(self):
+		self.assertEqual(tl.safe_pred(self.other_node), self.some_node)
+		self.assertIsNone(tl.safe_pred(self.root))
+		self.assertIsNone(tl.safe_pred(self.some_node))
+		self.assertIsNone(tl.safe_pred(self.some_orphan))
+		self.assertIsNone(tl.safe_pred(self.other_orphan))