Merge for issue #15744: add tests for the writelines() method of file objects.

1 files changed, 22 insertions, 0 deletions

diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 906952c..0847961 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -10,6 +10,7 @@ from weakref import proxy
 from functools import wraps
 
 from test.support import TESTFN, check_warnings, run_unittest, make_bad_fd
+from collections import UserList
 
 from _io import FileIO as _FileIO
 
@@ -68,6 +69,27 @@ class AutoFileTests(unittest.TestCase):
         n = self.f.readinto(a)
         self.assertEqual(array('b', [1, 2]), a[:n])
 
+    def testWritelinesList(self):
+        l = [b'123', b'456']
+        self.f.writelines(l)
+        self.f.close()
+        self.f = _FileIO(TESTFN, 'rb')
+        buf = self.f.read()
+        self.assertEqual(buf, b'123456')
+
+    def testWritelinesUserList(self):
+        l = UserList([b'123', b'456'])
+        self.f.writelines(l)
+        self.f.close()
+        self.f = _FileIO(TESTFN, 'rb')
+        buf = self.f.read()
+        self.assertEqual(buf, b'123456')
+
+    def testWritelinesError(self):
+        self.assertRaises(TypeError, self.f.writelines, [1, 2, 3])
+        self.assertRaises(TypeError, self.f.writelines, None)
+        self.assertRaises(TypeError, self.f.writelines, "abc")
+
     def test_none_args(self):
         self.f.write(b"hi\nbye\nabc")
         self.f.close()