--- a/testcases.py	Mon Feb 28 15:10:40 2011 +0000
+++ b/testcases.py	Mon Feb 28 15:32:22 2011 +0000
@@ -52,6 +52,7 @@
 # Exceptions
 
 class TestCaseNotPassed(Exception): __slots__ = ()
+class TestCaseSkipped(TestCaseNotPassed): __slots__ = ()
 class TimeLimitExceeded(TestCaseNotPassed): __slots__ = ()
 class CPUTimeLimitExceeded(TimeLimitExceeded): __slots__ = ()
 class WallTimeLimitExceeded(TimeLimitExceeded): __slots__ = ()
@@ -160,7 +161,8 @@
 			case.realoutname = case.problem.config.dummyoutname
 	
 	@abstractmethod
-	def test(case): raise NotImplementedError
+	def test(case):
+		raise NotImplementedError
 	
 	def __call__(case, callback):
 		case.has_called_back = False
@@ -178,6 +180,14 @@
 				callback()
 			case.cleanup()
 	
+	@property
+	def has_iofiles(case):
+		return False
+	
+	@property
+	def has_ansfile(case):
+		return False
+	
 	def cleanup(case):
 		#if getattr(case, 'infile', None):
 		#	case.infile.close()
@@ -229,6 +239,13 @@
 			raise CannotReadAnswerFile(e)
 
 
+class SkippedTestCase(TestCase):
+	__slots__ = ()
+	
+	def test(case, callback):
+		raise TestCaseSkipped
+
+
 class ValidatedTestCase(TestCase):
 	__slots__ = 'validator'
 	
@@ -278,9 +295,17 @@
 class BatchTestCase(ValidatedTestCase):
 	__slots__ = ()
 	
+	@property
+	def has_iofiles(case):
+		return (not case.problem.config.stdio or
+		        case.validator and not callable(case.validator))
+	
+	@property
+	def has_ansfile(case):
+		return case.validator and not callable(case.validator)
+	
 	def test(case, callback):
 		case.open_infile()
-		case.time_started = None
 		if case.problem.config.stdio:
 			if options.erase and not case.validator or not case.problem.config.inname:
 				# TODO: re-use the same file name if possible
@@ -414,9 +439,14 @@
 			if not group:
 				continue
 			yield problem.TestGroup(prob.config.groupweight.get(k, prob.config.groupweight.get(None)))
+			case_type = _types[prob.config.kind]
 			for j, i in enumerate(group):
 				s = str(i).zfill(prob.config.padtests)
-				yield _types[prob.config.kind](prob, s, False, getpoints(i, j, k))
+				if not (yield case_type(prob, s, False, getpoints(i, j, k))):
+					if options.skim:
+						case_type = SkippedTestCase
+				else:
+					yield
 			yield problem.test_context_end
 	else:
 		for i in prob.config.tests: