diff --git a/info4/kapitel-8/Interpreter/test_loop_interpreter.py b/info4/kapitel-8/Interpreter/test_loop_interpreter.py
new file mode 100644
index 0000000000000000000000000000000000000000..f8552a8db0e7e79e17539fa86c4b981f742b8449
--- /dev/null
+++ b/info4/kapitel-8/Interpreter/test_loop_interpreter.py
@@ -0,0 +1,209 @@
+from interpreter import interpret
+import unittest
+
+
+class InterpreterTest(unittest.TestCase):
+    def test_assignment_default_zero(self):
+        self.assertEqual(interpret('x0:=x0 + 0'), 0)
+        self.assertEqual(interpret('x0:=x1 + 0'), 0)
+        self.assertEqual(interpret('x0:=x2 + 0'), 0)
+
+    def test_assignment_non_negative(self):
+        self.assertEqual(interpret('x0:=x0-1'), 0)
+        self.assertEqual(interpret('x0:=x1-1'), 0)
+        self.assertEqual(interpret('x0:=x2-6'), 0)
+
+    def test_assignment_number(self):
+        self.assertEqual(interpret("x0:=5"), 5)
+        self.assertEqual(interpret("x0:=2"), 2)
+        self.assertEqual(interpret('x0:=3'), 3)
+
+    def test_assignment_variable(self):
+        self.assertEqual(interpret('x0:=x0+1'), 1)
+        self.assertEqual(interpret('x0:= 5; x0:=x0-1'), 4)
+        self.assertEqual(interpret('x0:=x1-1; x0:=x0+1'), 1)
+
+    def test_assignment_wrong_syntax(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=x2')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=0+x2')
+        with self.assertRaises(SyntaxError):
+            interpret('x5:=-1+x4')
+        with self.assertRaises(SyntaxError):
+            interpret('x5:=-x3+x1')
+        with self.assertRaises(SyntaxError):
+            interpret('x5:=x1-x3')
+        with self.assertRaises(SyntaxError):
+            interpret('x2:=x1+x4')
+        with self.assertRaises(SyntaxError):
+            interpret('x2:=x1+2;')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=c')
+        with self.assertRaises(SyntaxError):
+            interpret('xi:=2')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=xj+1')
+
+    def test_loop_assignment(self):
+        self.assertEqual(interpret('x1:=1; LOOP x1 DO x0:=1 END'), 1)
+        self.assertEqual(interpret('x1:=2; LOOP x1 DO x0:=x0 + 2 END'), 4)
+
+    def test_loop_empty_assignment(self):
+        self.assertEqual(interpret('LOOP x1 DO x0:=1 END'), 0)
+        self.assertEqual(interpret('x2:=2;LOOP x1 DO x0:=x2+1 END'), 0)
+
+    def test_loop_nested_assignment(self):
+        self.assertEqual(interpret('x1:=3; LOOP x1 DO x2:=x2+1; LOOP x2 DO x0:=x0+1 END END'), 6)
+        self.assertEqual(interpret('x1:=3; x2:=3; LOOP x1 DO x2:=x2-1; LOOP x2 DO x0:=x0+1 END END'), 3)
+
+    def test_loop_forbidden_identifier(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; LOOP x1 DO x1:=x1+1 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; LOOP x1 DO x2:=x1 + 2 END')
+
+    def test_loop_empty_forbidden_identifier(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x2 DO x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO x2:=x1 - 2 END')
+
+    def test_loop_nested_forbidden_identifier(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=2; LOOP x1 DO LOOP x1 DO x0:=x0+1 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; x2:=2 LOOP x1 DO LOOP x2 DO x1:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; x2:=2 LOOP x1 DO LOOP x2 DO x2:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; x2:=2 LOOP x1 DO LOOP x2 DO x0:=x2+2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; x2:=2 LOOP x1 DO LOOP x2 DO x0:=x1-2 END END')
+
+    def test_loop_nested_empty_forbidden_identifier(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO LOOP x2 DO x2:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO LOOP x2 DO x0:=x2+2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO LOOP x2 DO x0:=x1 + 0 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO LOOP x2 DO x1:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 DO LOOP x1 DO x2:=2 END END')
+
+    def test_loop_wrong_syntax(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP 2 DO x2:=5 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; LOOP x1 DO x2:=5; END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; LOOP x1 DO; x2:=5 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=1; LOOP x1 DO x2:=5 END;')
+
+    def test_assignment_with_loop(self):
+        self.assertEqual(interpret('x0:=2; LOOP x0 DO x1:=x1+1 END; x0:=x1+0'), 2)
+        self.assertEqual(interpret('x1:=x1+1; LOOP x0 DO x1:=x1+1 END; x0:=x1+0'), 1)
+
+    def test_syntax_unnecessary_semicolon(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1:=x1+1 END;')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1:=x1+1;; x1:=x1+1 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=x1+1;; x1:=x1+1')
+        with self.assertRaises(SyntaxError):
+            interpret(';x1:=x1+1')
+
+    def test_syntax_missing_semicolon(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2 LOOP x0 DO x1:=x1+1 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1:=x1+1 x1:=x1+1 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO x1:=x1+1 x1:=x1+1 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1:=x1+1 END x0:=x1+0')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO x1:=x1+1 END x0:=x1+0')
+
+    def test_syntax_missing_do(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x1 x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x1:=2; LOOP x1 x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP x1 x2:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=1; LOOP x0 DO LOOP x1 x2:=2 END END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=1; x1:=2; LOOP x0 DO LOOP x1 x2:=2 END END')
+
+    def test_syntax_missing_end(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP x1 DO x2:=2')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=5; LOOP x0 DO LOOP x1 DO x2:=2')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=4; x1:=7; LOOP x0 DO LOOP x1 DO x2:=2')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP x1 DO x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO LOOP x1 DO x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; x1:=3; LOOP x0 DO LOOP x1 DO x2:=2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0 := 2; LOOP x0 DO x1 := 1; x2 := x2 + 1')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1:=2; x2:=0')
+
+    def test_syntax_missing_program(self):
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP x1 DO END END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP x1 DO x2:=2; END')
+
+    def test_syntax_missing_operator(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=x1 2')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x2 DO x0:=x1 2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x2:=3; LOOP x2 DO x1:=x1 2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x2 DO LOOP x3 DO x1:=x1 2 END END')
+
+    def test_syntax_missing_equals(self):
+        with self.assertRaises(SyntaxError):
+            interpret('x1 2')
+        with self.assertRaises(SyntaxError):
+            interpret('x1 x2+2')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1 2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO x1 2 END')
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO x1 x2+3 END')
+        with self.assertRaises(SyntaxError):
+            interpret('x0:=2; LOOP x0 DO x1 x2-1 END')
+
+    def test_syntax_missing_identifier(self):
+        with self.assertRaises(SyntaxError):
+            interpret("x1:=; LOOP x1 DO x2:=2 END")
+        with self.assertRaises(SyntaxError):
+            interpret("LOOP x1 DO x2:= END")
+        with self.assertRaises(SyntaxError):
+            interpret("LOOP x1 DO x2:=x0+ END")
+        with self.assertRaises(SyntaxError):
+            interpret('LOOP x0 DO LOOP DO x1:=x2+0 END END')
+
+    def test_newlines(self):
+        self.assertEqual(interpret('''x2:=3;
+        x0:=x2+2'''), 5)
+        self.assertEqual(interpret('x1:=x1-2;\n x0:=x1+2'), 2)