On second thought, make can_execute_unsafe_code a function returning a boolean.

common/lib/capa/capa/responsetypes.py

@@ -504,7 +504,7 @@ class JavascriptResponse(LoncapaResponse):
     def call_node(self, args):
         # Node.js code is un-sandboxed. If the XModuleSystem says we aren't
         # allowed to run unsafe code, then stop now.
-        if not self.system.can_execute_unsafe_code:
+        if not self.system.can_execute_unsafe_code():
             raise LoncapaProblemError("Execution of unsafe Javascript code is not allowed.")
 
         subprocess_args = ["node"]

common/lib/capa/capa/tests/__init__.py

@@ -40,7 +40,7 @@ def test_system():
         node_path=os.environ.get("NODE_PATH", "/usr/local/lib/node_modules"),
         anonymous_student_id='student',
         cache=None,
-        can_execute_unsafe_code=False,
+        can_execute_unsafe_code=lambda: False,
     )
     return the_system
 

common/lib/capa/capa/tests/test_responsetypes.py

@@ -747,7 +747,7 @@ class JavascriptResponseTest(ResponseTest):
         os.system("coffee -c %s" % (coffee_file_path))
 
         system = test_system()
-        system.can_execute_unsafe_code = True
+        system.can_execute_unsafe_code = lambda: True
         problem = self.build_problem(
             system=system,
             generator_src="test_problem_generator.js",
@@ -765,7 +765,7 @@ class JavascriptResponseTest(ResponseTest):
         # If the system says to disallow unsafe code execution, then making
         # this problem will raise an exception.
         system = test_system()
-        system.can_execute_unsafe_code = False
+        system.can_execute_unsafe_code = lambda: False
 
         with self.assertRaises(LoncapaProblemError):
             problem = self.build_problem(

common/lib/xmodule/xmodule/x_module.py

@@ -702,7 +702,7 @@ class ModuleSystem(object):
                  open_ended_grading_interface=None,
                  s3_interface=None,
                  cache=None,
-                 can_execute_unsafe_code=False,
+                 can_execute_unsafe_code=None,
                 ):
         '''
         Create a closure around the system environment.
@@ -750,8 +750,8 @@ class ModuleSystem(object):
             .get(key) returns an object from the cache or None.
             .set(key, value, timeout_secs=None) stores a value in the cache with a timeout.
 
-        can_execute_unsafe_code - A boolean, whether or not to allow the execution
-            of unsafe, unsandboxed code.
+        can_execute_unsafe_code - A function returning a boolean, whether or
+            not to allow the execution of unsafe, unsandboxed code.
 
         '''
         self.ajax_url = ajax_url
@@ -778,7 +778,7 @@ class ModuleSystem(object):
         self.s3_interface = s3_interface
 
         self.cache = cache or DoNothingCache()
-        self.can_execute_unsafe_code = can_execute_unsafe_code
+        self.can_execute_unsafe_code = can_execute_unsafe_code or (lambda: False)
 
     def get(self, attr):
         '''	provide uniform access to attributes (like etree).'''