Marc-Andre Lemburg <mal@lemburg.com>:

New test for huge formatting strings (these could cause core
dumps in previous versions).

By Trent Mick.

Lib/test/test_format.py

+from test_support import verbose
+import string, sys
+
+# test string formatting operator (I am not sure if this is being tested
+# elsewhere but, surely, some of the given cases are *not* tested because
+# they crash python)
+# test on unicode strings as well
+
+def testformat(formatstr, args, output=None):
+	if verbose:
+		if output:
+			print "%s %% %s =? %s ..." %\
+				(repr(formatstr), repr(args), repr(output)),
+		else:
+			print "%s %% %s works? ..." % (repr(formatstr), repr(args)),
+	try:
+		result = formatstr % args
+	except OverflowError:
+		if verbose:
+			print 'overflow (this is fine)'
+	else:
+		if output and result != output:
+			if verbose:
+				print 'no'
+			print "%s %% %s == %s != %s" %\
+				(repr(formatstr), repr(args), repr(result), repr(output))
+		else:
+			if verbose:
+				print 'yes'
+
+def testboth(formatstr, *args):
+	testformat(formatstr, *args)
+	testformat(unicode(formatstr), *args)
+		
+
+testboth("%.1d", (1,), "1")
+testboth("%.*d", (sys.maxint,1))  # expect overflow
+testboth("%.100d", (1,), '0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001')
+testboth("%#.117x", (1,), '0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001')
+testboth("%#.118x", (1,), '0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001')
+
+testboth("%f", (1.0,), "1.000000")
+# these are trying to test the limits of the internal magic-number-length
+# formatting buffer, if that number changes then these tests are less
+# effective
+testboth("%#.*g", (109, -1.e+49/3.))
+testboth("%#.*g", (110, -1.e+49/3.))
+testboth("%#.*g", (110, -1.e+100/3.))
+
+# test some ridiculously large precision, expect overflow
+testboth('%12.*f', (123456, 1.0))
+