[2.7] bpo-33751: Fix test_file. (GH-7378) (GH-7445)

testModeStrings and testTruncateOnWindows were depended on
a file leaked in other tests.

Also improve cleaning up after tests.
(cherry picked from commit c2745d2d)

Lib/test/test_file.py

@@ -12,7 +12,8 @@ from weakref import proxy
 import io
 import _pyio as pyio
 
-from test.test_support import TESTFN, run_unittest
+from test.support import TESTFN, run_unittest
+from test import support
 from UserList import UserList
 
 class AutoFileTests(unittest.TestCase):
@@ -24,7 +25,7 @@ class AutoFileTests(unittest.TestCase):
     def tearDown(self):
         if self.f:
             self.f.close()
-        os.remove(TESTFN)
+        support.unlink(TESTFN)
 
     def testWeakRefs(self):
         # verify weak references
@@ -143,8 +144,12 @@ class PyAutoFileTests(AutoFileTests):
 
 class OtherFileTests(unittest.TestCase):
 
+    def tearDown(self):
+        support.unlink(TESTFN)
+
     def testModeStrings(self):
         # check invalid mode strings
+        self.open(TESTFN, 'wb').close()
         for mode in ("", "aU", "wU+"):
             try:
                 f = self.open(TESTFN, mode)
@@ -191,7 +196,6 @@ class OtherFileTests(unittest.TestCase):
         # SF bug <http://www.python.org/sf/801631>
         # "file.truncate fault on windows"
 
-        os.unlink(TESTFN)
         f = self.open(TESTFN, 'wb')
 
         try:
@@ -215,7 +219,6 @@ class OtherFileTests(unittest.TestCase):
                 self.fail("File size after ftruncate wrong %d" % size)
         finally:
             f.close()
-            os.unlink(TESTFN)
 
     def testIteration(self):
         # Test the complex interaction when mixing file-iteration and the
@@ -236,7 +239,6 @@ class OtherFileTests(unittest.TestCase):
         methods = [("readline", ()), ("read", ()), ("readlines", ()),
                    ("readinto", (array("b", b" "*100),))]
 
-        try:
         # Prepare the testfile
         bag = self.open(TESTFN, "wb")
         bag.write(filler * nchunks)
@@ -314,8 +316,6 @@ class OtherFileTests(unittest.TestCase):
                 self.fail("read* failed after next() consumed file")
         finally:
             f.close()
-        finally:
-            os.unlink(TESTFN)
 
 class COtherFileTests(OtherFileTests):
     open = io.open
@@ -325,14 +325,8 @@ class PyOtherFileTests(OtherFileTests):
 
 
 def test_main():
-    # Historically, these tests have been sloppy about removing TESTFN.
-    # So get rid of it no matter what.
-    try:
     run_unittest(CAutoFileTests, PyAutoFileTests,
                  COtherFileTests, PyOtherFileTests)
-    finally:
-        if os.path.exists(TESTFN):
-            os.unlink(TESTFN)
 
 if __name__ == '__main__':
     test_main()