diff --git a/osc/commandline.py b/osc/commandline.py
index c1c042b0..5bd5a7b3 100644
--- a/osc/commandline.py
+++ b/osc/commandline.py
@@ -4249,13 +4249,10 @@ Please submit there instead, or use --nodevelproject to force direct submission.
     def _prdiff_output_diff(self, opts, rdiff):
         if opts.diffstat:
             print()
-            p = subprocess.Popen("diffstat",
-                                 stdin=subprocess.PIPE,
-                                 stdout=subprocess.PIPE,
-                                 close_fds=True)
-            p.stdin.write(rdiff)
-            p.stdin.close()
-            print("".join(decode_it(x) for x in p.stdout.readlines()))
+            with subprocess.Popen("diffstat", stdin=subprocess.PIPE, stdout=subprocess.PIPE, close_fds=True) as p:
+                p.stdin.write(rdiff)
+                p.stdin.close()
+                print("".join(decode_it(x) for x in p.stdout.readlines()))
         elif opts.unified:
             print()
             if isinstance(rdiff, str):
diff --git a/osc/connection.py b/osc/connection.py
index 0154c0f8..db7afd64 100644
--- a/osc/connection.py
+++ b/osc/connection.py
@@ -123,6 +123,24 @@ HTTP_PROXY_MANAGER = get_proxy_manager("HTTP_PROXY")
 HTTPS_PROXY_MANAGER = get_proxy_manager("HTTPS_PROXY")
 
 
+def http_request_wrap_file(func):
+    """
+    Turn file path into a file object and close it automatically
+    by using a context manager.
+    """
+    def new_func(method, url, headers=None, data=None, file=None):
+        if file:
+            with open(file, "rb") as f:
+                return func(method, url, headers, data, file=f)
+        else:
+            return func(method, url, headers, data, file)
+
+    new_func.__name__ = func.__name__
+    new_func.__doc__ = func.__doc__
+    return new_func
+
+
+@http_request_wrap_file
 def http_request(method, url, headers=None, data=None, file=None):
     """
     Send a HTTP request to a server.
@@ -162,8 +180,8 @@ def http_request(method, url, headers=None, data=None, file=None):
             data = data.encode("utf-8")
         content_length = len(data)
     elif file:
-        content_length = os.path.getsize(file)
-        data = open(file, "rb")
+        content_length = os.fstat(file.fileno()).st_size
+        data = file
     else:
         content_length = 0
 
diff --git a/osc/core.py b/osc/core.py
index 3716281e..f039315f 100644
--- a/osc/core.py
+++ b/osc/core.py
@@ -2023,7 +2023,8 @@ class Package:
                 if not add:
                     tmpl = b'-%s'
                     ltmpl = b'@@ -1,%d +0,0 @@\n'
-                lines = [tmpl % i for i in open(fname, 'rb').readlines()]
+                with open(fname, 'rb') as f:
+                    lines = [tmpl % i for i in f.readlines()]
                 if len(lines):
                     diff.append(ltmpl % len(lines))
                     if not lines[-1].endswith(b'\n'):
@@ -3277,7 +3278,8 @@ def store_readlist(dir, name):
 
     r = []
     if os.path.exists(os.path.join(dir, store, name)):
-        r = [line.rstrip('\n') for line in open(os.path.join(dir, store, name))]
+        with open(os.path.join(dir, store, name)) as f:
+            r = [line.rstrip('\n') for line in f]
     return r
 
 def read_tobeadded(dir):
@@ -3293,7 +3295,8 @@ def read_sizelimit(dir):
     fname = os.path.join(dir, store, '_size_limit')
 
     if os.path.exists(fname):
-        r = open(fname).readline().strip()
+        with open(fname) as f:
+            r = f.readline().strip()
 
     if r is None or not r.isdigit():
         return None
@@ -3351,7 +3354,8 @@ def check_store_version(dir):
 
     versionfile = os.path.join(dir, store, '_osclib_version')
     try:
-        v = open(versionfile).read().strip()
+        with open(versionfile) as f:
+            v = f.read().strip()
     except:
         v = ''
 
@@ -4741,7 +4745,8 @@ def binary(s):
 
 def binary_file(fn):
     """read 4096 bytes from a file named fn, and call binary() on the data"""
-    return binary(open(fn, 'rb').read(4096))
+    with open(fn, 'rb') as f:
+        return binary(f.read(4096))
 
 
 def get_source_file_diff(dir, filename, rev, oldfilename = None, olddir = None, origfilename = None):
@@ -6500,7 +6505,8 @@ def store_read_project(dir):
     global store
 
     try:
-        p = open(os.path.join(dir, store, '_project')).readlines()[0].strip()
+        with open(os.path.join(dir, store, '_project')) as f:
+            p = f.readline().strip()
     except OSError:
         msg = 'Error: \'%s\' is not an osc project dir or working copy' % os.path.abspath(dir)
         if os.path.exists(os.path.join(dir, '.svn')):
@@ -6513,7 +6519,8 @@ def store_read_package(dir):
     global store
 
     try:
-        p = open(os.path.join(dir, store, '_package')).readlines()[0].strip()
+        with open(os.path.join(dir, store, '_package')) as f:
+            p = f.readline().strip()
     except OSError:
         msg = 'Error: \'%s\' is not an osc package working copy' % os.path.abspath(dir)
         if os.path.exists(os.path.join(dir, '.svn')):
@@ -6541,7 +6548,8 @@ def store_read_apiurl(dir, defaulturl=True):
 
     fname = os.path.join(dir, store, '_apiurl')
     try:
-        url = open(fname).readlines()[0].strip()
+        with open(fname) as f:
+            url = f.readlines()[0].strip()
         # this is needed to get a proper apiurl
         # (former osc versions may stored an apiurl with a trailing slash etc.)
         apiurl = conf.urljoin(*conf.parse_apisrv_url(None, url))
@@ -6612,8 +6620,8 @@ def store_read_file(dir, file):
     global store
 
     try:
-        content = open(os.path.join(dir, store, file)).read()
-        return content
+        with open(os.path.join(dir, store, file)) as f:
+            return f.read()
     except:
         return None
 
diff --git a/tests/common.py b/tests/common.py
index 0cb5c200..0e6766b8 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -233,8 +233,7 @@ class OscTestCase(unittest.TestCase):
 
     def _check_list(self, fname, exp):
         fname = os.path.join('.osc', fname)
-        self.assertTrue(os.path.exists(fname))
-        self.assertEqual(open(fname).read(), exp)
+        self.assertFileContentEqual(fname, exp)
 
     def _check_addlist(self, exp):
         self._check_list('_to_be_added', exp)
@@ -262,6 +261,22 @@ class OscTestCase(unittest.TestCase):
             self.assertTrue(os.path.exists(os.path.join('.osc', i.get('name'))))
             self.assertEqual(osc.core.dgst(os.path.join('.osc', i.get('name'))), i.get('md5'))
 
+    def assertFilesEqual(self, first, second):
+        self.assertTrue(os.path.exists(first))
+        self.assertTrue(os.path.exists(second))
+        with open(first) as f1, open(second) as f2:
+            self.assertEqual(f1.read(), f2.read())
+
+    def assertFileContentEqual(self, file_path, expected_content):
+        self.assertTrue(os.path.exists(file_path))
+        with open(file_path) as f:
+            self.assertEqual(f.read(), expected_content)
+
+    def assertFileContentNotEqual(self, file_path, expected_content):
+        self.assertTrue(os.path.exists(file_path))
+        with open(file_path) as f:
+            self.assertNotEqual(f.read(), expected_content)
+
     def assertXMLEqual(self, act, exp):
         if xml_equal(act, exp):
             return
diff --git a/tests/test_addfiles.py b/tests/test_addfiles.py
index 4dba1f3f..bfee7ff4 100644
--- a/tests/test_addfiles.py
+++ b/tests/test_addfiles.py
@@ -66,12 +66,12 @@ class TestAddFiles(OscTestCase):
         """replace a deleted file ('foo')"""
         self._change_to_pkg('simple')
         p = osc.core.Package('.')
-        open('foo', 'w').write('replaced file\n')
+        with open('foo', 'w') as f:
+            f.write('replaced file\n')
         p.addfile('foo')
         exp = 'A    foo\n'
         self.assertEqual(sys.stdout.getvalue(), exp)
-        self.assertTrue(os.path.exists(os.path.join('.osc', 'foo')))
-        self.assertNotEqual(open(os.path.join('.osc', 'foo')).read(), 'replaced file\n')
+        self.assertFileContentNotEqual(os.path.join('.osc', 'foo'), 'replaced file\n')
         self.assertFalse(os.path.exists(os.path.join('.osc', '_to_be_deleted')))
         self._check_status(p, 'foo', 'R')
         self._check_addlist('foo\n')
diff --git a/tests/test_commit.py b/tests/test_commit.py
index 2aab8b1e..667ab6ea 100644
--- a/tests/test_commit.py
+++ b/tests/test_commit.py
@@ -40,7 +40,7 @@ class TestCommit(OscTestCase):
         self.assertEqual(sys.stdout.getvalue(), exp)
         self._check_digests('testSimple_cfilesremote')
         self.assertTrue(os.path.exists('nochange'))
-        self.assertEqual(open('nochange').read(), open(os.path.join('.osc', 'nochange')).read())
+        self.assertFilesEqual('nochange', os.path.join('.osc', 'nochange'))
         self._check_status(p, 'nochange', ' ')
         self._check_status(p, 'foo', ' ')
         self._check_status(p, 'merge', ' ')
@@ -64,7 +64,7 @@ class TestCommit(OscTestCase):
         self.assertEqual(sys.stdout.getvalue(), exp)
         self._check_digests('testAddfile_cfilesremote')
         self.assertTrue(os.path.exists('add'))
-        self.assertEqual(open('add').read(), open(os.path.join('.osc', 'add')).read())
+        self.assertFilesEqual('add', os.path.join('.osc', 'add'))
         self.assertFalse(os.path.exists(os.path.join('.osc', '_to_be_added')))
         self._check_status(p, 'add', ' ')
         self._check_status(p, 'foo', ' ')
@@ -241,7 +241,7 @@ class TestCommit(OscTestCase):
         self.assertEqual(sys.stdout.getvalue(), exp)
         self._check_digests('testAddfile_cfilesremote')
         self.assertTrue(os.path.exists('add'))
-        self.assertEqual(open('add').read(), open(os.path.join('.osc', 'add')).read())
+        self.assertFilesEqual('add', os.path.join('.osc', 'add'))
         self.assertFalse(os.path.exists(os.path.join('.osc', '_to_be_added')))
         self._check_status(p, 'add', ' ')
         self._check_status(p, 'foo', ' ')
@@ -341,7 +341,7 @@ class TestCommit(OscTestCase):
         self.assertEqual(sys.stdout.getvalue(), exp)
         self._check_digests('testSimple_cfilesremote')
         self.assertTrue(os.path.exists('nochange'))
-        self.assertEqual(open('nochange').read(), open(os.path.join('.osc', 'nochange')).read())
+        self.assertFilesEqual('nochange', os.path.join('.osc', 'nochange'))
         self._check_status(p, 'nochange', ' ')
         self._check_status(p, 'foo', ' ')
         self._check_status(p, 'merge', ' ')
diff --git a/tests/test_init_package.py b/tests/test_init_package.py
index fa0bf5f1..30519ac4 100644
--- a/tests/test_init_package.py
+++ b/tests/test_init_package.py
@@ -84,7 +84,8 @@ class TestInitPackage(OscTestCase):
         """initialize a package dir (dir is a file)"""
         pac_dir = os.path.join(self.tmpdir, 'testpkg')
         os.mkdir(pac_dir)
-        open(os.path.join(pac_dir, osc.core.store), 'w').write('foo\n')
+        with open(os.path.join(pac_dir, osc.core.store), 'w') as f:
+            f.write('foo\n')
         self.assertRaises(osc.oscerr.OscIOError, osc.core.Package.init_package, 'http://localhost', 'osctest', 'testpkg', pac_dir)
 
 if __name__ == '__main__':
diff --git a/tests/test_repairwc.py b/tests/test_repairwc.py
index ee58ff33..cb224b02 100644
--- a/tests/test_repairwc.py
+++ b/tests/test_repairwc.py
@@ -192,7 +192,7 @@ class TestRepairWC(OscTestCase):
         p = osc.core.Package('.', wc_check=False)
         p.wc_repair('http://localhost')
         self.assertTrue(os.path.exists(os.path.join('.osc', '_apiurl')))
-        self.assertEqual(open(os.path.join('.osc', '_apiurl')).read(), 'http://localhost\n')
+        self.assertFileContentEqual(os.path.join('.osc', '_apiurl'), 'http://localhost\n')
         self.assertEqual(p.apiurl, 'http://localhost')
 
     def test_invalidapiurl(self):
@@ -201,7 +201,7 @@ class TestRepairWC(OscTestCase):
         p = osc.core.Package('.', wc_check=False)
         p.wc_repair('http://localhost')
         self.assertTrue(os.path.exists(os.path.join('.osc', '_apiurl')))
-        self.assertEqual(open(os.path.join('.osc', '_apiurl')).read(), 'http://localhost\n')
+        self.assertFileContentEqual(os.path.join('.osc', '_apiurl'), 'http://localhost\n')
         self.assertEqual(p.apiurl, 'http://localhost')
 
     def test_noapiurlNotExistingApiurl(self):
@@ -223,7 +223,7 @@ class TestRepairWC(OscTestCase):
         prj.wc_repair('http://localhost')
         self.assertTrue(os.path.exists(os.path.join(storedir, '_apiurl')))
         self.assertTrue(os.path.exists(os.path.join(storedir, '_apiurl')))
-        self.assertEqual(open(os.path.join(storedir, '_apiurl')).read(), 'http://localhost\n')
+        self.assertFileContentEqual(os.path.join(storedir, '_apiurl'), 'http://localhost\n')
 
 
 if __name__ == '__main__':
diff --git a/tests/test_request.py b/tests/test_request.py
index 89807786..9bd84b7a 100644
--- a/tests/test_request.py
+++ b/tests/test_request.py
@@ -322,7 +322,7 @@ class TestRequest(OscTestCase):
 
     def test_read_request1(self):
         """read in a request"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_read_request1.xml')).read().strip()
+        xml = self._get_fixture('test_read_request1.xml')
         r = osc.core.Request()
         r.read(ET.fromstring(xml))
         self.assertEqual(r.reqid, '42')
@@ -353,7 +353,7 @@ class TestRequest(OscTestCase):
 
     def test_read_request2(self):
         """read in a request (with reviews)"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_read_request2.xml')).read().strip()
+        xml = self._get_fixture('test_read_request2.xml')
         r = osc.core.Request()
         r.read(ET.fromstring(xml))
         self.assertEqual(r.reqid, '123')
@@ -427,7 +427,7 @@ class TestRequest(OscTestCase):
 
     def test_request_list_view1(self):
         """test the list_view method"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_request_list_view1.xml')).read().strip()
+        xml = self._get_fixture('test_request_list_view1.xml')
         exp = """\
     62  State:new        By:Admin        When:2010-12-29T14:57:25
         set_bugowner:    buguser                                            foo
@@ -444,7 +444,7 @@ class TestRequest(OscTestCase):
 
     def test_request_list_view2(self):
         """test the list_view method (with history elements and description)"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_request_list_view2.xml')).read().strip()
+        xml = self._get_fixture('test_request_list_view2.xml')
         r = osc.core.Request()
         r.read(ET.fromstring(xml))
         exp = """\
@@ -458,7 +458,7 @@ class TestRequest(OscTestCase):
 
     def test_request_str1(self):
         """test the __str__ method"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_request_str1.xml')).read().strip()
+        xml = self._get_fixture('test_request_str1.xml')
         r = osc.core.Request()
         r = osc.core.Request()
         r.read(ET.fromstring(xml))
@@ -555,7 +555,7 @@ Comment: <no comment>"""
 
     def test_get_actions(self):
         """test get_actions method"""
-        xml = open(os.path.join(self._get_fixtures_dir(), 'test_request_list_view1.xml')).read().strip()
+        xml = self._get_fixture('test_request_list_view1.xml')
         r = osc.core.Request()
         r.read(ET.fromstring(xml))
         sr_actions = r.get_actions('submit')
diff --git a/tests/test_revertfiles.py b/tests/test_revertfiles.py
index a6b93d88..3248a312 100644
--- a/tests/test_revertfiles.py
+++ b/tests/test_revertfiles.py
@@ -93,7 +93,7 @@ class TestRevertFiles(OscTestCase):
         storefile = os.path.join('.osc', fname)
         self.assertTrue(os.path.exists(fname))
         self.assertTrue(os.path.exists(storefile))
-        self.assertEqual(open(fname).read(), open(storefile).read())
+        self.assertFilesEqual(fname, storefile)
 
 if __name__ == '__main__':
     import unittest
diff --git a/tests/test_update.py b/tests/test_update.py
index c0b2f168..f6c81a4b 100644
--- a/tests/test_update.py
+++ b/tests/test_update.py
@@ -115,7 +115,7 @@ class TestUpdate(OscTestCase):
         self.assertEqual(sys.stdout.getvalue(), exp)
         self._check_deletelist('foo\n')
         self._check_conflictlist('merge\n')
-        self.assertEqual(open('foo').read(), open(os.path.join('.osc', 'foo')).read())
+        self.assertFilesEqual('foo', os.path.join('.osc', 'foo'))
         self._check_digests('testUpdateLocalDeletions_files')
 
     @GET('http://localhost/source/osctest/restore?rev=latest', file='testUpdateRestore_files')
@@ -201,11 +201,9 @@ class TestUpdate(OscTestCase):
         exp = 'A    bigfile\nD    _service:exists\nA    _service:bar\nA    _service:foo\nAt revision 2.\n'
         self.assertEqual(sys.stdout.getvalue(), exp)
         self.assertFalse(os.path.exists(os.path.join('.osc', '_service:bar')))
-        self.assertTrue(os.path.exists('_service:bar'))
-        self.assertEqual(open('_service:bar').read(), 'another service\n')
+        self.assertFileContentEqual('_service:bar', 'another service\n')
         self.assertFalse(os.path.exists(os.path.join('.osc', '_service:foo')))
-        self.assertTrue(os.path.exists('_service:foo'))
-        self.assertEqual(open('_service:foo').read(), 'small\n')
+        self.assertFileContentEqual('_service:foo', 'small\n')
         self.assertTrue(os.path.exists('_service:exists'))
         self._check_digests('testUpdateServiceFilesAddDelete_files', '_service:foo', '_service:bar')