Control traceback length via assignment config

otter/assign/assignment.py

@@ -19,6 +19,13 @@ class Assignment(fica.Config, Loggable):
     Configurations for the assignment.
     """
 
+
+    traceback_length: Optional[str] = fica.Key(
+        description="how much of the traceback message to print upon test failure",
+        default="assertion_msg",
+        validator=fica.validators.choice(["full", "assertion_msg", "none"])
+    )
+
     name: Optional[str] = fica.Key(
         description="a name for the assignment (to validate that students submit to the correct " \
             "autograder)",

otter/test_files/ok_test.py

@@ -51,7 +51,17 @@ def run_doctest(name, doctest_string, global_environment):
     if result.failed == 0:
         return (True, '')
     else:
-        return False, runresults.getvalue()
+        from ..assign.assignment import Assignment
+        if Assignment().traceback_length == 'full':
+            return False, runresults.getvalue()
+        elif Assignment().traceback_length == 'assertion_msg':
+            err_msg = runresults.getvalue()
+            if 'AssertionError: ' in err_msg:
+                return False, err_msg[err_msg.index('AssertionError: '):]
+            else:
+                return False, ''
+        elif Assignment().traceback_length == 'none':
+            return False, ''
 
 
 class OKTestFile(TestFile):