diff --git a/tests/test_jasinta.py b/tests/test_jasinta.py
--- a/tests/test_jasinta.py
+++ b/tests/test_jasinta.py
@@ -6,9 +6,9 @@ from pyjsparser import parse
 from jasinta import interpret
 
 
-class TestBasicAddition(TestCase):
+class TestBasics(TestCase):
 	@patch("builtins.print")
-	def test_interpret(self, mock_print):
+	def test_addition(self, mock_print):
 		s = """var a=3;
 var b=1;
 var c=a+b;
@@ -17,10 +17,8 @@ document.write(c);"""
 		interpret(parse(s))
 		mock_print.assert_called_with(4)
 
-
-class TestAssignment(TestCase):
 	@patch("builtins.print")
-	def test_interpret(self, mock_print):
+	def test_assignment(self, mock_print):
 		s = """var a=1;
 var b=1;
 a+=b;
@@ -29,3 +27,18 @@ document.write(b);"""
 
 		interpret(parse(s))
 		mock_print.assert_called_with(3)
+
+
+class TestString(TestCase):
+	@patch("builtins.print")
+	def test_assignment(self, mock_print):
+		s = """var s = "abcdefgh";
+var a = s.charAt(0);
+var bcd = s.slice(1, 4);
+var efg = s.substr(4, 3);
+var h = String.fromCharCode(104);
+document.cookie = a+bcd+efg+h;
+document.write(document.cookie);"""
+
+		interpret(parse(s))
+		mock_print.assert_called_with("abcdefgh")