Use 'with' for opening most file and SFTPFIle objects

12 files changed, 281 insertions, 363 deletions

diff --git a/demos/demo_sftp.py b/demos/demo_sftp.py
index 1cccffc2..9476f76c 100755
--- a/demos/demo_sftp.py
+++ b/demos/demo_sftp.py
@@ -96,7 +96,8 @@ try:
         sftp.mkdir("demo_sftp_folder")
     except IOError:
         print('(assuming demo_sftp_folder/ already exists)')
-    sftp.open('demo_sftp_folder/README', 'w').write('This was created by demo_sftp.py.\n')
+    with sftp.open('demo_sftp_folder/README', 'w') as f:
+        f.write('This was created by demo_sftp.py.\n')
     with open('demo_sftp.py', 'r') as f:
         data = f.read()
     sftp.open('demo_sftp_folder/demo_sftp.py', 'w').write(data)
diff --git a/paramiko/auth_handler.py b/paramiko/auth_handler.py
index 3e389da8..5046cac5 100644
--- a/paramiko/auth_handler.py
+++ b/paramiko/auth_handler.py
@@ -93,7 +93,7 @@ class AuthHandler (object):
             self._request_auth()
         finally:
             self.transport.lock.release()
-    
+
     def auth_interactive(self, username, handler, event, submethods=''):
         """
         response_list = handler(title, instructions, prompt_list)
@@ -108,7 +108,7 @@ class AuthHandler (object):
             self._request_auth()
         finally:
             self.transport.lock.release()
-    
+
     def abort(self):
         if self.auth_event is not None:
             self.auth_event.set()
diff --git a/paramiko/client.py b/paramiko/client.py
index 3ce01687..7cf897fa 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -192,11 +192,10 @@ class SSHClient (object):
         if self.known_hosts is not None:
             self.load_host_keys(self.known_hosts)
 
-        f = open(filename, 'w')
-        for hostname, keys in self._host_keys.items():
-            for keytype, key in keys.items():
-                f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
-        f.close()
+        with open(filename, 'w') as f:
+            for hostname, keys in self._host_keys.items():
+                for keytype, key in keys.items():
+                    f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
 
     def get_host_keys(self):
         """
diff --git a/paramiko/hostkeys.py b/paramiko/hostkeys.py
index 16f7f901..cf586a29 100644
--- a/paramiko/hostkeys.py
+++ b/paramiko/hostkeys.py
@@ -172,8 +172,7 @@ class HostKeys (MutableMapping):
 
         @raise IOError: if there was an error reading the file
         """
-        f = open(filename, 'r')
-        try:
+        with open(filename, 'r') as f:
             for lineno, line in enumerate(f):
                 line = line.strip()
                 if (len(line) == 0) or (line[0] == '#'):
@@ -186,8 +185,6 @@ class HostKeys (MutableMapping):
                             e.hostnames.remove(h)
                     if len(e.hostnames):
                         self._entries.append(e)
-        finally:
-            f.close()
 
     def save(self, filename):
         """
@@ -203,14 +200,11 @@ class HostKeys (MutableMapping):
 
         @since: 1.6.1
         """
-        f = open(filename, 'w')
-        try:
+        with open(filename, 'w') as f:
             for e in self._entries:
                 line = e.to_line()
                 if line:
                     f.write(line)
-        finally:
-            f.close()
 
     def lookup(self, hostname):
         """
diff --git a/paramiko/pkey.py b/paramiko/pkey.py
index a2f27edd..0a174ca7 100644
--- a/paramiko/pkey.py
+++ b/paramiko/pkey.py
@@ -282,11 +282,8 @@ class PKey (object):
             encrypted, and C{password} is C{None}.
         @raise SSHException: if the key file is invalid.
         """
-        f = open(filename, 'r')
-        try:
+        with open(filename, 'r') as f:
             data = self._read_private_key(tag, f, password)
-        finally:
-            f.close()
         return data
 
     def _read_private_key(self, tag, f, password=None):
@@ -354,13 +351,10 @@ class PKey (object):
 
         @raise IOError: if there was an error writing the file.
         """
-        f = open(filename, 'w', o600)
-        try:
+        with open(filename, 'w', o600) as f:
             # grrr... the mode doesn't always take hold
             os.chmod(filename, o600)
             self._write_private_key(tag, f, data, password)
-        finally:
-            f.close()
 
     def _write_private_key(self, tag, f, data, password=None):
         f.write('-----BEGIN %s PRIVATE KEY-----\n' % tag)
diff --git a/paramiko/primes.py b/paramiko/primes.py
index 13ec52d0..d10a15fb 100644
--- a/paramiko/primes.py
+++ b/paramiko/primes.py
@@ -113,8 +113,7 @@ class ModulusPack (object):
         @raise IOError: passed from any file operations that fail.
         """
         self.pack = {}
-        f = open(filename, 'r')
-        try:
+        with open(filename, 'r') as f:
             for line in f:
                 line = line.strip()
                 if (len(line) == 0) or (line[0] == '#'):
@@ -123,8 +122,6 @@ class ModulusPack (object):
                     self._parse_modulus(line)
                 except:
                     continue
-        finally:
-            f.close()
 
     def get_modulus(self, min, prefer, max):
         bitsizes = sorted(self.pack.keys())
diff --git a/paramiko/sftp_client.py b/paramiko/sftp_client.py
index 1082c6cb..2b3eb187 100644
--- a/paramiko/sftp_client.py
+++ b/paramiko/sftp_client.py
@@ -561,10 +561,9 @@ class SFTPClient (BaseSFTP):
 
         @since: 1.4
         """
-        fr = self.file(remotepath, 'wb')
-        fr.set_pipelined(True)
-        size = 0
-        try:
+        with self.file(remotepath, 'wb') as fr:
+            fr.set_pipelined(True)
+            size = 0
             while True:
                 data = fl.read(32768)
                 fr.write(data)
@@ -573,8 +572,6 @@ class SFTPClient (BaseSFTP):
                     callback(size, file_size)
                 if len(data) == 0:
                     break
-        finally:
-            fr.close()
         if confirm:
             s = self.stat(remotepath)
             if s.st_size != size:
@@ -610,11 +607,8 @@ class SFTPClient (BaseSFTP):
         @since: 1.4
         """
         file_size = os.stat(localpath).st_size
-        fl = open(localpath, 'rb')
-        try:
+        with open(localpath, 'rb') as fl:
             return self.putfo(fl, remotepath, os.stat(localpath).st_size, callback, confirm)
-        finally:
-            fl.close()
 
     def getfo(self, remotepath, fl, callback=None):
         """
@@ -636,10 +630,9 @@ class SFTPClient (BaseSFTP):
 
         @since: 1.4
         """
-        fr = self.open(remotepath, 'rb')
-        file_size = self.stat(remotepath).st_size
-        fr.prefetch()
-        try:
+        with self.open(remotepath, 'rb') as fr:
+            file_size = self.stat(remotepath).st_size
+            fr.prefetch()
             size = 0
             while True:
                 data = fr.read(32768)
@@ -649,8 +642,6 @@ class SFTPClient (BaseSFTP):
                     callback(size, file_size)
                 if len(data) == 0:
                     break
-        finally:
-            fr.close()
         return size
 
     def get(self, remotepath, localpath, callback=None):
@@ -671,11 +662,8 @@ class SFTPClient (BaseSFTP):
         @since: 1.4
         """
         file_size = self.stat(remotepath).st_size
-        fl = open(localpath, 'wb')
-        try:
+        with open(localpath, 'wb') as fl:
             size = self.getfo(remotepath, fl, callback)
-        finally:
-            fl.close()
         s = os.stat(localpath)
         if s.st_size != size:
             raise IOError('size mismatch in get!  %d != %d' % (s.st_size, size))
diff --git a/paramiko/sftp_server.py b/paramiko/sftp_server.py
index 7dcef6b4..4539edea 100644
--- a/paramiko/sftp_server.py
+++ b/paramiko/sftp_server.py
@@ -166,11 +166,8 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         if attr._flags & attr.FLAG_AMTIME:
             os.utime(filename, (attr.st_atime, attr.st_mtime))
         if attr._flags & attr.FLAG_SIZE:
-            f = open(filename, 'w+')
-            try:
+            with open(filename, 'w+') as f:
                 f.truncate(attr.st_size)
-            finally:
-                f.close()
     set_file_attr = staticmethod(set_file_attr)
 
 
diff --git a/tests/test_hostkeys.py b/tests/test_hostkeys.py
index a7621d8b..5290a4dc 100644
--- a/tests/test_hostkeys.py
+++ b/tests/test_hostkeys.py
@@ -56,9 +56,8 @@ Ngw3qIch/WgRmMHy4kBq1SsXMjQCte1So6HBMvBPIW5SiMTmjCfZZiw4AYHK+B/JaOwaG9yRg2Ejg\
 class HostKeysTest (unittest.TestCase):
 
     def setUp(self):
-        f = open('hostfile.temp', 'w')
-        f.write(test_hosts_file)
-        f.close()
+        with open('hostfile.temp', 'w') as f:
+            f.write(test_hosts_file)
 
     def tearDown(self):
         os.unlink('hostfile.temp')
diff --git a/tests/test_sftp.py b/tests/test_sftp.py
index 70fd9103..e3dc7882 100755
--- a/tests/test_sftp.py
+++ b/tests/test_sftp.py
@@ -186,10 +186,9 @@ class SFTPTest (unittest.TestCase):
         """
         verify that a file can be created and written, and the size is correct.
         """
-        f = sftp.open(FOLDER + '/duck.txt', 'w')
         try:
-            f.write(ARTICLE)
-            f.close()
+            with sftp.open(FOLDER + '/duck.txt', 'w') as f:
+                f.write(ARTICLE)
             self.assertEqual(sftp.stat(FOLDER + '/duck.txt').st_size, 1483)
         finally:
             sftp.remove(FOLDER + '/duck.txt')
@@ -209,40 +208,36 @@ class SFTPTest (unittest.TestCase):
         """
         verify that a file can be opened for append, and tell() still works.
         """
-        f = sftp.open(FOLDER + '/append.txt', 'w')
         try:
-            f.write('first line\nsecond line\n')
-            self.assertEqual(f.tell(), 23)
-            f.close()
-
-            f = sftp.open(FOLDER + '/append.txt', 'a+')
-            f.write('third line!!!\n')
-            self.assertEqual(f.tell(), 37)
-            self.assertEqual(f.stat().st_size, 37)
-            f.seek(-26, f.SEEK_CUR)
-            self.assertEqual(f.readline(), 'second line\n')
+            with sftp.open(FOLDER + '/append.txt', 'w') as f:
+                f.write('first line\nsecond line\n')
+                self.assertEqual(f.tell(), 23)
+
+            with sftp.open(FOLDER + '/append.txt', 'a+') as f:
+                f.write('third line!!!\n')
+                self.assertEqual(f.tell(), 37)
+                self.assertEqual(f.stat().st_size, 37)
+                f.seek(-26, f.SEEK_CUR)
+                self.assertEqual(f.readline(), 'second line\n')
         finally:
-            f.close()
             sftp.remove(FOLDER + '/append.txt')
 
     def test_5_rename(self):
         """
         verify that renaming a file works.
         """
-        f = sftp.open(FOLDER + '/first.txt', 'w')
         try:
-            f.write('content!\n')
-            f.close()
+            with sftp.open(FOLDER + '/first.txt', 'w') as f:
+                f.write('content!\n')
             sftp.rename(FOLDER + '/first.txt', FOLDER + '/second.txt')
             try:
                 f = sftp.open(FOLDER + '/first.txt', 'r')
                 self.assertTrue(False, 'no exception on reading nonexistent file')
             except IOError:
                 pass
-            f = sftp.open(FOLDER + '/second.txt', 'r')
-            f.seek(-6, f.SEEK_END)
-            self.assertEqual(u(f.read(4)), 'tent')
-            f.close()
+            with sftp.open(FOLDER + '/second.txt', 'r') as f:
+                f.seek(-6, f.SEEK_END)
+                self.assertEqual(u(f.read(4)), 'tent')
         finally:
             try:
                 sftp.remove(FOLDER + '/first.txt')
@@ -300,10 +295,9 @@ class SFTPTest (unittest.TestCase):
         """
         verify that the setstat functions (chown, chmod, utime, truncate) work.
         """
-        f = sftp.open(FOLDER + '/special', 'w')
         try:
-            f.write('x' * 1024)
-            f.close()
+            with sftp.open(FOLDER + '/special', 'w') as f:
+                f.write('x' * 1024)
 
             stat = sftp.stat(FOLDER + '/special')
             sftp.chmod(FOLDER + '/special', (stat.st_mode & ~o777) | o600)
@@ -339,40 +333,38 @@ class SFTPTest (unittest.TestCase):
         verify that the fsetstat functions (chown, chmod, utime, truncate)
         work on open files.
         """
-        f = sftp.open(FOLDER + '/special', 'w')
         try:
-            f.write('x' * 1024)
-            f.close()
-
-            f = sftp.open(FOLDER + '/special', 'r+')
-            stat = f.stat()
-            f.chmod((stat.st_mode & ~o777) | o600)
-            stat = f.stat()
-
-            expected_mode = o600
-            if sys.platform == 'win32':
-                # chmod not really functional on windows
-                expected_mode = o666
-            if sys.platform == 'cygwin':
-                # even worse.
-                expected_mode = o644
-            self.assertEqual(stat.st_mode & o777, expected_mode)
-            self.assertEqual(stat.st_size, 1024)
-
-            mtime = stat.st_mtime - 3600
-            atime = stat.st_atime - 1800
-            f.utime((atime, mtime))
-            stat = f.stat()
-            self.assertEqual(stat.st_mtime, mtime)
-            if sys.platform not in ('win32', 'cygwin'):
-                self.assertEqual(stat.st_atime, atime)
-
-            # can't really test chown, since we'd have to know a valid uid.
-
-            f.truncate(512)
-            stat = f.stat()
-            self.assertEqual(stat.st_size, 512)
-            f.close()
+            with sftp.open(FOLDER + '/special', 'w') as f:
+                f.write('x' * 1024)
+
+            with sftp.open(FOLDER + '/special', 'r+') as f:
+                stat = f.stat()
+                f.chmod((stat.st_mode & ~o777) | o600)
+                stat = f.stat()
+
+                expected_mode = o600
+                if sys.platform == 'win32':
+                    # chmod not really functional on windows
+                    expected_mode = o666
+                if sys.platform == 'cygwin':
+                    # even worse.
+                    expected_mode = o644
+                self.assertEqual(stat.st_mode & o777, expected_mode)
+                self.assertEqual(stat.st_size, 1024)
+
+                mtime = stat.st_mtime - 3600
+                atime = stat.st_atime - 1800
+                f.utime((atime, mtime))
+                stat = f.stat()
+                self.assertEqual(stat.st_mtime, mtime)
+                if sys.platform not in ('win32', 'cygwin'):
+                    self.assertEqual(stat.st_atime, atime)
+
+                # can't really test chown, since we'd have to know a valid uid.
+
+                f.truncate(512)
+                stat = f.stat()
+                self.assertEqual(stat.st_size, 512)
         finally:
             sftp.remove(FOLDER + '/special')
 
@@ -384,25 +376,23 @@ class SFTPTest (unittest.TestCase):
         buffering is reset on 'seek'.
         """
         try:
-            f = sftp.open(FOLDER + '/duck.txt', 'w')
-            f.write(ARTICLE)
-            f.close()
+            with sftp.open(FOLDER + '/duck.txt', 'w') as f:
+                f.write(ARTICLE)
 
-            f = sftp.open(FOLDER + '/duck.txt', 'r+')
-            line_number = 0
-            loc = 0
-            pos_list = []
-            for line in f:
-                line_number += 1
-                pos_list.append(loc)
-                loc = f.tell()
-            f.seek(pos_list[6], f.SEEK_SET)
-            self.assertEqual(f.readline(), 'Nouzilly, France.\n')
-            f.seek(pos_list[17], f.SEEK_SET)
-            self.assertEqual(f.readline()[:4], 'duck')
-            f.seek(pos_list[10], f.SEEK_SET)
-            self.assertEqual(f.readline(), 'duck types were equally resistant to exogenous insulin compared with chicken.\n')
-            f.close()
+            with sftp.open(FOLDER + '/duck.txt', 'r+') as f:
+                line_number = 0
+                loc = 0
+                pos_list = []
+                for line in f:
+                    line_number += 1
+                    pos_list.append(loc)
+                    loc = f.tell()
+                f.seek(pos_list[6], f.SEEK_SET)
+                self.assertEqual(f.readline(), 'Nouzilly, France.\n')
+                f.seek(pos_list[17], f.SEEK_SET)
+                self.assertEqual(f.readline()[:4], 'duck')
+                f.seek(pos_list[10], f.SEEK_SET)
+                self.assertEqual(f.readline(), 'duck types were equally resistant to exogenous insulin compared with chicken.\n')
         finally:
             sftp.remove(FOLDER + '/duck.txt')
 
@@ -411,17 +401,15 @@ class SFTPTest (unittest.TestCase):
         create a text file, seek back and change part of it, and verify that the
         changes worked.
         """
-        f = sftp.open(FOLDER + '/testing.txt', 'w')
         try:
-            f.write('hello kitty.\n')
-            f.seek(-5, f.SEEK_CUR)
-            f.write('dd')
-            f.close()
+            with sftp.open(FOLDER + '/testing.txt', 'w') as f:
+                f.write('hello kitty.\n')
+                f.seek(-5, f.SEEK_CUR)
+                f.write('dd')
 
             self.assertEqual(sftp.stat(FOLDER + '/testing.txt').st_size, 13)
-            f = sftp.open(FOLDER + '/testing.txt', 'r')
-            data = f.read(20)
-            f.close()
+            with sftp.open(FOLDER + '/testing.txt', 'r') as f:
+                data = f.read(20)
             self.assertEqual(data, 'hello kiddy.\n')
         finally:
             sftp.remove(FOLDER + '/testing.txt')
@@ -434,16 +422,14 @@ class SFTPTest (unittest.TestCase):
             # skip symlink tests on windows
             return
 
-        f = sftp.open(FOLDER + '/original.txt', 'w')
         try:
-            f.write('original\n')
-            f.close()
+            with sftp.open(FOLDER + '/original.txt', 'w') as f:
+                f.write('original\n')
             sftp.symlink('original.txt', FOLDER + '/link.txt')
             self.assertEqual(sftp.readlink(FOLDER + '/link.txt'), 'original.txt')
 
-            f = sftp.open(FOLDER + '/link.txt', 'r')
-            self.assertEqual(f.readlines(), ['original\n'])
-            f.close()
+            with sftp.open(FOLDER + '/link.txt', 'r') as f:
+                self.assertEqual(f.readlines(), ['original\n'])
 
             cwd = sftp.normalize('.')
             if cwd[-1] == '/':
@@ -477,18 +463,16 @@ class SFTPTest (unittest.TestCase):
         """
         verify that buffered writes are automatically flushed on seek.
         """
-        f = sftp.open(FOLDER + '/happy.txt', 'w', 1)
         try:
-            f.write('full line.\n')
-            f.write('partial')
-            f.seek(9, f.SEEK_SET)
-            f.write('?\n')
-            f.close()
-
-            f = sftp.open(FOLDER + '/happy.txt', 'r')
-            self.assertEqual(f.readline(), 'full line?\n')
-            self.assertEqual(f.read(7), 'partial')
-            f.close()
+            with sftp.open(FOLDER + '/happy.txt', 'w', 1) as f:
+                f.write('full line.\n')
+                f.write('partial')
+                f.seek(9, f.SEEK_SET)
+                f.write('?\n')
+
+            with sftp.open(FOLDER + '/happy.txt', 'r') as f:
+                self.assertEqual(f.readline(), 'full line?\n')
+                self.assertEqual(f.read(7), 'partial')
         finally:
             try:
                 sftp.remove(FOLDER + '/happy.txt')
@@ -544,9 +528,8 @@ class SFTPTest (unittest.TestCase):
             self.assertEqual(['beta'], sftp.listdir('.'))
 
             sftp.chdir('beta')
-            f = sftp.open('fish', 'w')
-            f.write('hello\n')
-            f.close()
+            with sftp.open('fish', 'w') as f:
+                f.write('hello\n')
             sftp.chdir('..')
             self.assertEqual(['fish'], sftp.listdir('beta'))
             sftp.chdir('..')
@@ -575,17 +558,15 @@ class SFTPTest (unittest.TestCase):
         fd, localname = mkstemp()
         os.close(fd)
         text = b('All I wanted was a plastic bunny rabbit.\n')
-        f = open(localname, 'wb')
-        f.write(text)
-        f.close()
+        with open(localname, 'wb') as f:
+            f.write(text)
         saved_progress = []
         def progress_callback(x, y):
             saved_progress.append((x, y))
         sftp.put(localname, FOLDER + '/bunny.txt', progress_callback)
 
-        f = sftp.open(FOLDER + '/bunny.txt', 'rb')
-        self.assertEqual(text, f.read(128))
-        f.close()
+        with sftp.open(FOLDER + '/bunny.txt', 'rb') as f:
+            self.assertEqual(text, f.read(128))
         self.assertEqual((41, 41), saved_progress[-1])
 
         os.unlink(localname)
@@ -594,9 +575,8 @@ class SFTPTest (unittest.TestCase):
         saved_progress = []
         sftp.get(FOLDER + '/bunny.txt', localname, progress_callback)
 
-        f = open(localname, 'rb')
-        self.assertEqual(text, f.read(128))
-        f.close()
+        with open(localname, 'rb') as f:
+            self.assertEqual(text, f.read(128))
         self.assertEqual((41, 41), saved_progress[-1])
 
         os.unlink(localname)
@@ -608,20 +588,18 @@ class SFTPTest (unittest.TestCase):
         (it's an sftp extension that we support, and may be the only ones who
         support it.)
         """
-        f = sftp.open(FOLDER + '/kitty.txt', 'w')
-        f.write('here kitty kitty' * 64)
-        f.close()
+        with sftp.open(FOLDER + '/kitty.txt', 'w') as f:
+            f.write('here kitty kitty' * 64)
 
         try:
-            f = sftp.open(FOLDER + '/kitty.txt', 'r')
-            sum = f.check('sha1')
-            self.assertEqual('91059CFC6615941378D413CB5ADAF4C5EB293402', u(hexlify(sum)).upper())
-            sum = f.check('md5', 0, 512)
-            self.assertEqual('93DE4788FCA28D471516963A1FE3856A', u(hexlify(sum)).upper())
-            sum = f.check('md5', 0, 0, 510)
-            self.assertEqual('EB3B45B8CD55A0707D99B177544A319F373183D241432BB2157AB9E46358C4AC90370B5CADE5D90336FC1716F90B36D6',
-                              u(hexlify(sum)).upper())
-            f.close()
+            with sftp.open(FOLDER + '/kitty.txt', 'r') as f:
+                sum = f.check('sha1')
+                self.assertEqual('91059CFC6615941378D413CB5ADAF4C5EB293402', u(hexlify(sum)).upper())
+                sum = f.check('md5', 0, 512)
+                self.assertEqual('93DE4788FCA28D471516963A1FE3856A', u(hexlify(sum)).upper())
+                sum = f.check('md5', 0, 0, 510)
+                self.assertEqual('EB3B45B8CD55A0707D99B177544A319F373183D241432BB2157AB9E46358C4AC90370B5CADE5D90336FC1716F90B36D6',
+                                  u(hexlify(sum)).upper())
         finally:
             sftp.unlink(FOLDER + '/kitty.txt')
 
@@ -645,9 +623,8 @@ class SFTPTest (unittest.TestCase):
         """
         verify that unicode strings are encoded into utf8 correctly.
         """
-        f = sftp.open(FOLDER + '/something', 'w')
-        f.write('okay')
-        f.close()
+        with sftp.open(FOLDER + '/something', 'w') as f:
+            f.write('okay')
 
         try:
             sftp.rename(FOLDER + '/something', FOLDER + '/' + unicode_folder)
@@ -660,9 +637,8 @@ class SFTPTest (unittest.TestCase):
         sftp.mkdir(FOLDER + '/' + unicode_folder)
         try:
             sftp.chdir(FOLDER + '/' + unicode_folder)
-            f = sftp.open('something', 'w')
-            f.write('okay')
-            f.close()
+            with sftp.open('something', 'w') as f:
+                f.write('okay')
             sftp.unlink('something')
         finally:
             sftp.chdir()
@@ -675,14 +651,12 @@ class SFTPTest (unittest.TestCase):
         f = sftp.open(FOLDER + '/zero', 'w')
         f.close()
         try:
-            f = sftp.open(FOLDER + '/zero', 'r')
-            f.readv([(0, 12)])
-            f.close()
+            with sftp.open(FOLDER + '/zero', 'r') as f:
+                f.readv([(0, 12)])
 
-            f = sftp.open(FOLDER + '/zero', 'r')
-            f.prefetch()
-            f.read(100)
-            f.close()
+            with sftp.open(FOLDER + '/zero', 'r') as f:
+                f.prefetch()
+                f.read(100)
         finally:
             sftp.unlink(FOLDER + '/zero')
 
@@ -695,9 +669,8 @@ class SFTPTest (unittest.TestCase):
         fd, localname = mkstemp()
         os.close(fd)
         text = 'All I wanted was a plastic bunny rabbit.\n'
-        f = open(localname, 'w')
-        f.write(text)
-        f.close()
+        with open(localname, 'w') as f:
+            f.write(text)
         saved_progress = []
         def progress_callback(x, y):
             saved_progress.append((x, y))
@@ -705,9 +678,8 @@ class SFTPTest (unittest.TestCase):
 
         self.assertEqual(SFTPAttributes().attr, res.attr)
 
-        f = sftp.open(FOLDER + '/bunny.txt', 'r')
-        self.assertEqual(text, f.read(128))
-        f.close()
+        with sftp.open(FOLDER + '/bunny.txt', 'r') as f:
+            self.assertEqual(text, f.read(128))
         self.assertEqual((41, 41), saved_progress[-1])
 
         os.unlink(localname)
@@ -719,19 +691,17 @@ class SFTPTest (unittest.TestCase):
 
         does not work except through paramiko.  :(  openssh fails.
         """
-        f = sftp.open(FOLDER + '/append.txt', 'a')
         try:
-            f.write('first line\nsecond line\n')
-            f.seek(11, f.SEEK_SET)
-            f.write('third line\n')
-            f.close()
-
-            f = sftp.open(FOLDER + '/append.txt', 'r')
-            self.assertEqual(f.stat().st_size, 34)
-            self.assertEqual(f.readline(), 'first line\n')
-            self.assertEqual(f.readline(), 'second line\n')
-            self.assertEqual(f.readline(), 'third line\n')
-            f.close()
+            with sftp.open(FOLDER + '/append.txt', 'a') as f:
+                f.write('first line\nsecond line\n')
+                f.seek(11, f.SEEK_SET)
+                f.write('third line\n')
+
+            with sftp.open(FOLDER + '/append.txt', 'r') as f:
+                self.assertEqual(f.stat().st_size, 34)
+                self.assertEqual(f.readline(), 'first line\n')
+                self.assertEqual(f.readline(), 'second line\n')
+                self.assertEqual(f.readline(), 'third line\n')
         finally:
             sftp.remove(FOLDER + '/append.txt')
 
diff --git a/tests/test_sftp_big.py b/tests/test_sftp_big.py
index dc9cba93..6870c6b4 100644
--- a/tests/test_sftp_big.py
+++ b/tests/test_sftp_big.py
@@ -66,9 +66,8 @@ class BigSFTPTest (unittest.TestCase):
         numfiles = 100
         try:
             for i in range(numfiles):
-                f = sftp.open('%s/file%d.txt' % (FOLDER, i), 'w', 1)
-                f.write('this is file #%d.\n' % i)
-                f.close()
+                with sftp.open('%s/file%d.txt' % (FOLDER, i), 'w', 1) as f:
+                    f.write('this is file #%d.\n' % i)
                 sftp.chmod('%s/file%d.txt' % (FOLDER, i), o660)
 
             # now make sure every file is there, by creating a list of filenmes
@@ -76,9 +75,8 @@ class BigSFTPTest (unittest.TestCase):
             numlist = list(range(numfiles))
             while len(numlist) > 0:
                 r = numlist[random.randint(0, len(numlist) - 1)]
-                f = sftp.open('%s/file%d.txt' % (FOLDER, r))
-                self.assertEqual(f.readline(), 'this is file #%d.\n' % r)
-                f.close()
+                with sftp.open('%s/file%d.txt' % (FOLDER, r)) as f:
+                    self.assertEqual(f.readline(), 'this is file #%d.\n' % r)
                 numlist.remove(r)
         finally:
             for i in range(numfiles):
@@ -95,12 +93,11 @@ class BigSFTPTest (unittest.TestCase):
         kblob = (1024 * 'x')
         start = time.time()
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'w') as f:
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
@@ -108,11 +105,10 @@ class BigSFTPTest (unittest.TestCase):
             sys.stderr.write('%ds ' % round(end - start))
             
             start = time.time()
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'r')
-            for n in range(1024):
-                data = f.read(1024)
-                self.assertEqual(data, kblob)
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'r') as f:
+                for n in range(1024):
+                    data = f.read(1024)
+                    self.assertEqual(data, kblob)
 
             end = time.time()
             sys.stderr.write('%ds ' % round(end - start))
@@ -127,13 +123,12 @@ class BigSFTPTest (unittest.TestCase):
         kblob = bytes().join([struct.pack('>H', n) for n in range(512)])
         start = time.time()
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'wb')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'wb') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
@@ -141,22 +136,21 @@ class BigSFTPTest (unittest.TestCase):
             sys.stderr.write('%ds ' % round(end - start))
             
             start = time.time()
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'rb')
-            f.prefetch()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'rb') as f:
+                f.prefetch()
 
-            # read on odd boundaries to make sure the bytes aren't getting scrambled
-            n = 0
-            k2blob = kblob + kblob
-            chunk = 629
-            size = 1024 * 1024
-            while n < size:
-                if n + chunk > size:
-                    chunk = size - n
-                data = f.read(chunk)
-                offset = n % 1024
-                self.assertEqual(data, k2blob[offset:offset + chunk])
-                n += chunk
-            f.close()
+                # read on odd boundaries to make sure the bytes aren't getting scrambled
+                n = 0
+                k2blob = kblob + kblob
+                chunk = 629
+                size = 1024 * 1024
+                while n < size:
+                    if n + chunk > size:
+                        chunk = size - n
+                    data = f.read(chunk)
+                    offset = n % 1024
+                    self.assertEqual(data, k2blob[offset:offset + chunk])
+                    n += chunk
 
             end = time.time()
             sys.stderr.write('%ds ' % round(end - start))
@@ -167,13 +161,12 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         kblob = bytes().join([struct.pack('>H', n) for n in range(512)])
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'wb')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'wb') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
             
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
@@ -182,20 +175,19 @@ class BigSFTPTest (unittest.TestCase):
             k2blob = kblob + kblob
             chunk = 793
             for i in range(10):
-                f = sftp.open('%s/hongry.txt' % FOLDER, 'rb')
-                f.prefetch()
-                base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
-                offsets = [base_offset + j * chunk for j in range(100)]
-                # randomly seek around and read them out
-                for j in range(100):
-                    offset = offsets[random.randint(0, len(offsets) - 1)]
-                    offsets.remove(offset)
-                    f.seek(offset)
-                    data = f.read(chunk)
-                    n_offset = offset % 1024
-                    self.assertEqual(data, k2blob[n_offset:n_offset + chunk])
-                    offset += chunk
-                f.close()
+                with sftp.open('%s/hongry.txt' % FOLDER, 'rb') as f:
+                    f.prefetch()
+                    base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
+                    offsets = [base_offset + j * chunk for j in range(100)]
+                    # randomly seek around and read them out
+                    for j in range(100):
+                        offset = offsets[random.randint(0, len(offsets) - 1)]
+                        offsets.remove(offset)
+                        f.seek(offset)
+                        data = f.read(chunk)
+                        n_offset = offset % 1024
+                        self.assertEqual(data, k2blob[n_offset:n_offset + chunk])
+                        offset += chunk
             end = time.time()
             sys.stderr.write('%ds ' % round(end - start))
         finally:
@@ -205,13 +197,12 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         kblob = bytes().join([struct.pack('>H', n) for n in range(512)])
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'wb')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'wb') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
@@ -220,21 +211,20 @@ class BigSFTPTest (unittest.TestCase):
             k2blob = kblob + kblob
             chunk = 793
             for i in range(10):
-                f = sftp.open('%s/hongry.txt' % FOLDER, 'rb')
-                base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
-                # make a bunch of offsets and put them in random order
-                offsets = [base_offset + j * chunk for j in range(100)]
-                readv_list = []
-                for j in range(100):
-                    o = offsets[random.randint(0, len(offsets) - 1)]
-                    offsets.remove(o)
-                    readv_list.append((o, chunk))
-                ret = f.readv(readv_list)
-                for i in range(len(readv_list)):
-                    offset = readv_list[i][0]
-                    n_offset = offset % 1024
-                    self.assertEqual(next(ret), k2blob[n_offset:n_offset + chunk])
-                f.close()
+                with sftp.open('%s/hongry.txt' % FOLDER, 'rb') as f:
+                    base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
+                    # make a bunch of offsets and put them in random order
+                    offsets = [base_offset + j * chunk for j in range(100)]
+                    readv_list = []
+                    for j in range(100):
+                        o = offsets[random.randint(0, len(offsets) - 1)]
+                        offsets.remove(o)
+                        readv_list.append((o, chunk))
+                    ret = f.readv(readv_list)
+                    for i in range(len(readv_list)):
+                        offset = readv_list[i][0]
+                        n_offset = offset % 1024
+                        self.assertEqual(next(ret), k2blob[n_offset:n_offset + chunk])
             end = time.time()
             sys.stderr.write('%ds ' % round(end - start))
         finally:
@@ -248,29 +238,26 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         kblob = (1024 * 'x')
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'w') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
 
             for i in range(10):
-                f = sftp.open('%s/hongry.txt' % FOLDER, 'r')
+                with sftp.open('%s/hongry.txt' % FOLDER, 'r') as f:
+                    f.prefetch()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'r') as f:
                 f.prefetch()
-                f.close()
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'r')
-            f.prefetch()
-            for n in range(1024):
-                data = f.read(1024)
-                self.assertEqual(data, kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+                for n in range(1024):
+                    data = f.read(1024)
+                    self.assertEqual(data, kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
         finally:
             sftp.remove('%s/hongry.txt' % FOLDER)
@@ -282,33 +269,31 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         kblob = bytes().join([struct.pack('>H', n) for n in range(512)])
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'wb')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'wb') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
             
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
 
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'rb')
-            f.prefetch()
-            data = f.read(1024)
-            self.assertEqual(data, kblob)
-            
-            chunk_size = 793
-            base_offset = 512 * 1024
-            k2blob = kblob + kblob
-            chunks = [(base_offset + (chunk_size * i), chunk_size) for i in range(20)]
-            for data in f.readv(chunks):
-                offset = base_offset % 1024
-                self.assertEqual(chunk_size, len(data))
-                self.assertEqual(k2blob[offset:offset + chunk_size], data)
-                base_offset += chunk_size
-
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'rb') as f:
+                f.prefetch()
+                data = f.read(1024)
+                self.assertEqual(data, kblob)
+
+                chunk_size = 793
+                base_offset = 512 * 1024
+                k2blob = kblob + kblob
+                chunks = [(base_offset + (chunk_size * i), chunk_size) for i in range(20)]
+                for data in f.readv(chunks):
+                    offset = base_offset % 1024
+                    self.assertEqual(chunk_size, len(data))
+                    self.assertEqual(k2blob[offset:offset + chunk_size], data)
+                    base_offset += chunk_size
+
             sys.stderr.write(' ')
         finally:
             sftp.remove('%s/hongry.txt' % FOLDER)
@@ -321,24 +306,22 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         kblob = bytes().join([struct.pack('>H', n) for n in range(512)])
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'wb')
-            f.set_pipelined(True)
-            for n in range(1024):
-                f.write(kblob)
-                if n % 128 == 0:
-                    sys.stderr.write('.')
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'wb') as f:
+                f.set_pipelined(True)
+                for n in range(1024):
+                    f.write(kblob)
+                    if n % 128 == 0:
+                        sys.stderr.write('.')
             sys.stderr.write(' ')
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
             
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'rb')
-            data = list(f.readv([(23 * 1024, 128 * 1024)]))
-            self.assertEqual(1, len(data))
-            data = data[0]
-            self.assertEqual(128 * 1024, len(data))
+            with sftp.open('%s/hongry.txt' % FOLDER, 'rb') as f:
+                data = list(f.readv([(23 * 1024, 128 * 1024)]))
+                self.assertEqual(1, len(data))
+                data = data[0]
+                self.assertEqual(128 * 1024, len(data))
             
-            f.close()
             sys.stderr.write(' ')
         finally:
             sftp.remove('%s/hongry.txt' % FOLDER)
@@ -350,9 +333,8 @@ class BigSFTPTest (unittest.TestCase):
         sftp = get_sftp()
         mblob = (1024 * 1024 * 'x')
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'w', 128 * 1024)
-            f.write(mblob)
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'w', 128 * 1024) as f:
+                f.write(mblob)
 
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
         finally:
@@ -367,21 +349,19 @@ class BigSFTPTest (unittest.TestCase):
         t.packetizer.REKEY_BYTES = 512 * 1024
         k32blob = (32 * 1024 * 'x')
         try:
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'w', 128 * 1024)
-            for i in range(32):
-                f.write(k32blob)
-            f.close()
-            
+            with sftp.open('%s/hongry.txt' % FOLDER, 'w', 128 * 1024) as f:
+                for i in range(32):
+                    f.write(k32blob)
+
             self.assertEqual(sftp.stat('%s/hongry.txt' % FOLDER).st_size, 1024 * 1024)
             self.assertNotEqual(t.H, t.session_id)
             
             # try to read it too.
-            f = sftp.open('%s/hongry.txt' % FOLDER, 'r', 128 * 1024)
-            f.prefetch()
-            total = 0
-            while total < 1024 * 1024:
-                total += len(f.read(32 * 1024))
-            f.close()
+            with sftp.open('%s/hongry.txt' % FOLDER, 'r', 128 * 1024) as f:
+                f.prefetch()
+                total = 0
+                while total < 1024 * 1024:
+                    total += len(f.read(32 * 1024))
         finally:
             sftp.remove('%s/hongry.txt' % FOLDER)
             t.packetizer.REKEY_BYTES = pow(2, 30)
diff --git a/tests/test_util.py b/tests/test_util.py
index dba52236..be107195 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -142,9 +142,8 @@ class UtilTest(ParamikoTest):
         self.assertEqual(hex, '9110e2f6793b69363e58173e9436b13a5a4b339005741d5c680e505f57d871347b4239f14fb5c46e857d5e100424873ba849ac699cea98d729e57b3e84378e8b')
 
     def test_5_host_keys(self):
-        f = open('hostfile.temp', 'w')
-        f.write(test_hosts_file)
-        f.close()
+        with open('hostfile.temp', 'w') as f:
+            f.write(test_hosts_file)
         try:
             hostdict = paramiko.util.load_host_keys('hostfile.temp')
             self.assertEqual(2, len(hostdict))