Issue #6268: Fix seek() method of codecs.open(), don't read the BOM twice
after seek(0)
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index f8563f6..306a3b2 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -1496,6 +1496,26 @@
self.assertEquals(srw.read(), u"\xfc")
+class BomTest(unittest.TestCase):
+ def test_seek0(self):
+ data = "1234567890"
+ tests = ("utf-16",
+ "utf-16-le",
+ "utf-16-be",
+ "utf-32",
+ "utf-32-le",
+ "utf-32-be")
+ for encoding in tests:
+ with codecs.open('foo', 'wt+', encoding=encoding) as f:
+ # Check if the BOM is written only once
+ f.write(data)
+ f.write(data)
+ f.seek(0)
+ self.assertEquals(f.read(), data * 2)
+ f.seek(0)
+ self.assertEquals(f.read(), data * 2)
+
+
def test_main():
test_support.run_unittest(
UTF32Test,
@@ -1524,6 +1544,7 @@
BasicStrTest,
CharmapTest,
WithStmtTest,
+ BomTest,
)