From d8bf6653c5564768c2aa22aa5bfa7b6036e30f84 Mon Sep 17 00:00:00 2001
From: Seth Sims <xzy3@cdc.gov>
Date: Mon, 19 Oct 2020 08:16:22 -0400
Subject: [PATCH 1/2] bpo-41270: Making NamedTemporaryFile act as its own
 iterator to mimic normal file objects.

NamedTemporaryFile returns a proxy object _TemporaryFileWrapper. However it does not proxy
the __next__ method so the object cannot be used by for loops or by the next() builtin
without calling iter() on it first. This changes that by explicity poxying the __next__
method.
---
 Lib/tempfile.py                                     |  3 +++
 Lib/test/test_tempfile.py                           | 13 +++++++++++++
 Misc/ACKS                                           |  1 +
 .../2020-07-10-14-33-52.bpo-41270.pjUqyd.rst        |  1 +
 4 files changed, 18 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2020-07-10-14-33-52.bpo-41270.pjUqyd.rst

diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index 770f72c25295cb..4d991623d80d59 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -499,6 +499,9 @@ def close(self):
         """
         self._closer.close()
 
+    def __next__(self):
+        return next(self.file)
+
     # iter() doesn't use __getattr__ to find the __iter__ method
     def __iter__(self):
         # Don't return iter(self.file), but yield from it to avoid closing
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index 8ace883d74bb24..a3f44551195b33 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -886,6 +886,19 @@ def make_file():
             self.assertEqual(l, lines[i])
         self.assertEqual(i, len(lines) - 1)
 
+    def test_next(self):
+        lines = [b'spam\n', b'eggs\n', b'beans\n']
+        with tempfile.NamedTemporaryFile(mode='w+b') as fd:
+            fd.write(b''.join(lines))
+            fd.seek(0)
+
+            for i, l in enumerate(lines):
+                self.assertEqual(l, next(fd))
+            self.assertEqual(i, len(lines) - 1)
+
+            with self.assertRaises(StopIteration):
+                next(fd)
+
     def test_creates_named(self):
         # NamedTemporaryFile creates files with names
         f = tempfile.NamedTemporaryFile()
diff --git a/Misc/ACKS b/Misc/ACKS
index 7f4a9bcbc0f8cd..dd00da8eeedf88 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1599,6 +1599,7 @@ Kirill Simonov
 Nathan Paul Simons
 Guilherme Simões
 Adam Simpkins
+Seth Sims
 Karthikeyan Singaravelan
 Mandeep Singh
 Ravi Sinha
diff --git a/Misc/NEWS.d/next/Library/2020-07-10-14-33-52.bpo-41270.pjUqyd.rst b/Misc/NEWS.d/next/Library/2020-07-10-14-33-52.bpo-41270.pjUqyd.rst
new file mode 100644
index 00000000000000..897099bb4fbb64
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-07-10-14-33-52.bpo-41270.pjUqyd.rst
@@ -0,0 +1 @@
+Added :func:`tempfile._TemporaryFileWrapper.__next__` so that the object returned by :func:`tempfile.NamedTemporaryFile` can be used to iterate over the contents of the file.

From ece481137a834cfd053355753f50b7ff2291ab0a Mon Sep 17 00:00:00 2001
From: Seth Sims <xzy3@cdc.gov>
Date: Mon, 2 Nov 2020 09:19:47 -0500
Subject: [PATCH 2/2] Addressing comments to simplify test case.

---
 Lib/test/test_tempfile.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index a3f44551195b33..11d71c7b841876 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -892,10 +892,7 @@ def test_next(self):
             fd.write(b''.join(lines))
             fd.seek(0)
 
-            for i, l in enumerate(lines):
-                self.assertEqual(l, next(fd))
-            self.assertEqual(i, len(lines) - 1)
-
+            self.assertEqual(list(fd), lines)
             with self.assertRaises(StopIteration):
                 next(fd)