New "exception" checker, for expected exceptions.

dmoj/checkers/__init__.py

@@ -8,6 +8,7 @@
     floatsrel,
     identical,
     linecount,
+    exception,
     linematches,
     rstripped,
     sorted,

dmoj/checkers/__init__.pyi

@@ -32,6 +32,7 @@ floatsabs: Checker
 floatsrel: Checker
 identical: Checker
 linecount: Checker
+exception: Checker
 linematches: Checker
 rstripped: Checker
 sorted: Checker

dmoj/checkers/exception.py

@@ -0,0 +1,30 @@
+from re import split as resplit
+from typing import Union
+
+from dmoj.result import CheckerResult
+from dmoj.utils.unicode import utf8bytes
+
+verdict = '\u2717\u2713'
+
+
+def check(
+    process_output: bytes, judge_output: bytes, point_value: float = 1, exceptionType: str = '', **kwargs
+) -> Union[CheckerResult, bool]:      
+    found = kwargs['result'].feedback.split('.')[-1]    
+    passed = (found == exceptionType or len(found) > 0 and len(exceptionType) == 0)
+
+    if  kwargs['result'].output != '':        
+        extended_feedback = ('Any type of exception' if exceptionType == '' else 'An exception of type "' + exceptionType) + '" was expected, but none has been raised:\nYour output: ' + kwargs['result'].output
+    else:
+        extended_feedback = None if passed else 'An exception was raised, but another exception type was expected:\nRaised: ' + found + '\nExpected: ' + exceptionType
+
+    kwargs['result'].proc_output = ''
+    kwargs['result'].result_flag = 0 if passed else 1
+
+    return CheckerResult(        
+        passed=passed,
+        points=point_value,        
+        extended_feedback=extended_feedback
+    )    
+
+check.run_on_error = True  # type: ignore