diff --git a/common/lib/xmodule/xmodule/html_module.py b/common/lib/xmodule/xmodule/html_module.py
index bbf24a6320..8af3693b3f 100644
--- a/common/lib/xmodule/xmodule/html_module.py
+++ b/common/lib/xmodule/xmodule/html_module.py
@@ -32,6 +32,8 @@ class HtmlModule(HtmlFields, XModule):
css = {'scss': [resource_string(__name__, 'css/html/display.scss')]}
def get_html(self):
+ if self.system.anonymous_student_id:
+ return self.data.replace("%%USER_ID%%", self.system.anonymous_student_id)
return self.data
diff --git a/common/lib/xmodule/xmodule/tests/test_html_module.py b/common/lib/xmodule/xmodule/tests/test_html_module.py
new file mode 100644
index 0000000000..e56e9babe7
--- /dev/null
+++ b/common/lib/xmodule/xmodule/tests/test_html_module.py
@@ -0,0 +1,40 @@
+import unittest
+
+from mock import Mock
+
+from xmodule.html_module import HtmlModule
+from xmodule.modulestore import Location
+
+from . import test_system
+
+class HtmlModuleSubstitutionTestCase(unittest.TestCase):
+ location = Location(["i4x", "edX", "toy", "html", "simple_html"])
+ descriptor = Mock()
+
+ def test_substitution_works(self):
+ sample_xml = '''%%USER_ID%%'''
+ module_data = {'data': sample_xml}
+ module_system = test_system()
+ module = HtmlModule(module_system, self.location, self.descriptor, module_data)
+ self.assertEqual(module.get_html(), str(module_system.anonymous_student_id))
+
+
+ def test_substitution_without_magic_string(self):
+ sample_xml = '''
+
+ Hi USER_ID!11!
+
+ '''
+ module_data = {'data': sample_xml}
+ module = HtmlModule(test_system(), self.location, self.descriptor, module_data)
+ self.assertEqual(module.get_html(), sample_xml)
+
+
+ def test_substitution_without_anonymous_student_id(self):
+ sample_xml = '''%%USER_ID%%'''
+ module_data = {'data': sample_xml}
+ module_system = test_system()
+ module_system.anonymous_student_id = None
+ module = HtmlModule(module_system, self.location, self.descriptor, module_data)
+ self.assertEqual(module.get_html(), sample_xml)
+