bpo-33751: Fix test_file. (GH-7378)

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

Also improve cleaning up after tests.

Lib/test/test_file.py

@@ -8,6 +8,7 @@ import io
 import _pyio as pyio
 
 from test.support import TESTFN
+from test import support
 from collections import UserList
 
 class AutoFileTests:
@@ -19,7 +20,7 @@ class AutoFileTests:
     def tearDown(self):
         if self.f:
             self.f.close()
-        os.remove(TESTFN)
+        support.unlink(TESTFN)
 
     def testWeakRefs(self):
         # verify weak references
@@ -137,8 +138,12 @@ class PyAutoFileTests(AutoFileTests, unittest.TestCase):
 
 class OtherFileTests:
 
+    def tearDown(self):
+        support.unlink(TESTFN)
+
     def testModeStrings(self):
         # check invalid mode strings
+        self.open(TESTFN, 'wb').close()
         for mode in ("", "aU", "wU+", "U+", "+U", "rU+"):
             try:
                 f = self.open(TESTFN, mode)
@@ -185,7 +190,6 @@ class OtherFileTests:
         # SF bug <http://www.python.org/sf/801631>
         # "file.truncate fault on windows"
 
-        os.unlink(TESTFN)
         f = self.open(TESTFN, 'wb')
 
         try:
@@ -209,7 +213,6 @@ class OtherFileTests:
                 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
@@ -230,87 +233,84 @@ class OtherFileTests:
         methods = [("readline", ()), ("read", ()), ("readlines", ()),
                    ("readinto", (array("b", b" "*100),))]
 
+        # Prepare the testfile
+        bag = self.open(TESTFN, "wb")
+        bag.write(filler * nchunks)
+        bag.writelines(testlines)
+        bag.close()
+        # Test for appropriate errors mixing read* and iteration
+        for methodname, args in methods:
+            f = self.open(TESTFN, 'rb')
+            if next(f) != filler:
+                self.fail, "Broken testfile"
+            meth = getattr(f, methodname)
+            meth(*args)  # This simply shouldn't fail
+            f.close()
+
+        # Test to see if harmless (by accident) mixing of read* and
+        # iteration still works. This depends on the size of the internal
+        # iteration buffer (currently 8192,) but we can test it in a
+        # flexible manner.  Each line in the bag o' ham is 4 bytes
+        # ("h", "a", "m", "\n"), so 4096 lines of that should get us
+        # exactly on the buffer boundary for any power-of-2 buffersize
+        # between 4 and 16384 (inclusive).
+        f = self.open(TESTFN, 'rb')
+        for i in range(nchunks):
+            next(f)
+        testline = testlines.pop(0)
         try:
-            # Prepare the testfile
-            bag = self.open(TESTFN, "wb")
-            bag.write(filler * nchunks)
-            bag.writelines(testlines)
-            bag.close()
-            # Test for appropriate errors mixing read* and iteration
-            for methodname, args in methods:
-                f = self.open(TESTFN, 'rb')
-                if next(f) != filler:
-                    self.fail, "Broken testfile"
-                meth = getattr(f, methodname)
-                meth(*args)  # This simply shouldn't fail
-                f.close()
+            line = f.readline()
+        except ValueError:
+            self.fail("readline() after next() with supposedly empty "
+                        "iteration-buffer failed anyway")
+        if line != testline:
+            self.fail("readline() after next() with empty buffer "
+                        "failed. Got %r, expected %r" % (line, testline))
+        testline = testlines.pop(0)
+        buf = array("b", b"\x00" * len(testline))
+        try:
+            f.readinto(buf)
+        except ValueError:
+            self.fail("readinto() after next() with supposedly empty "
+                        "iteration-buffer failed anyway")
+        line = buf.tobytes()
+        if line != testline:
+            self.fail("readinto() after next() with empty buffer "
+                        "failed. Got %r, expected %r" % (line, testline))
+
+        testline = testlines.pop(0)
+        try:
+            line = f.read(len(testline))
+        except ValueError:
+            self.fail("read() after next() with supposedly empty "
+                        "iteration-buffer failed anyway")
+        if line != testline:
+            self.fail("read() after next() with empty buffer "
+                        "failed. Got %r, expected %r" % (line, testline))
+        try:
+            lines = f.readlines()
+        except ValueError:
+            self.fail("readlines() after next() with supposedly empty "
+                        "iteration-buffer failed anyway")
+        if lines != testlines:
+            self.fail("readlines() after next() with empty buffer "
+                        "failed. Got %r, expected %r" % (line, testline))
+        f.close()
 
-            # Test to see if harmless (by accident) mixing of read* and
-            # iteration still works. This depends on the size of the internal
-            # iteration buffer (currently 8192,) but we can test it in a
-            # flexible manner.  Each line in the bag o' ham is 4 bytes
-            # ("h", "a", "m", "\n"), so 4096 lines of that should get us
-            # exactly on the buffer boundary for any power-of-2 buffersize
-            # between 4 and 16384 (inclusive).
-            f = self.open(TESTFN, 'rb')
-            for i in range(nchunks):
-                next(f)
-            testline = testlines.pop(0)
-            try:
-                line = f.readline()
-            except ValueError:
-                self.fail("readline() after next() with supposedly empty "
-                          "iteration-buffer failed anyway")
-            if line != testline:
-                self.fail("readline() after next() with empty buffer "
-                          "failed. Got %r, expected %r" % (line, testline))
-            testline = testlines.pop(0)
-            buf = array("b", b"\x00" * len(testline))
+        # Reading after iteration hit EOF shouldn't hurt either
+        f = self.open(TESTFN, 'rb')
+        try:
+            for line in f:
+                pass
             try:
+                f.readline()
                 f.readinto(buf)
+                f.read()
+                f.readlines()
             except ValueError:
-                self.fail("readinto() after next() with supposedly empty "
-                          "iteration-buffer failed anyway")
-            line = buf.tobytes()
-            if line != testline:
-                self.fail("readinto() after next() with empty buffer "
-                          "failed. Got %r, expected %r" % (line, testline))
-
-            testline = testlines.pop(0)
-            try:
-                line = f.read(len(testline))
-            except ValueError:
-                self.fail("read() after next() with supposedly empty "
-                          "iteration-buffer failed anyway")
-            if line != testline:
-                self.fail("read() after next() with empty buffer "
-                          "failed. Got %r, expected %r" % (line, testline))
-            try:
-                lines = f.readlines()
-            except ValueError:
-                self.fail("readlines() after next() with supposedly empty "
-                          "iteration-buffer failed anyway")
-            if lines != testlines:
-                self.fail("readlines() after next() with empty buffer "
-                          "failed. Got %r, expected %r" % (line, testline))
-            f.close()
-
-            # Reading after iteration hit EOF shouldn't hurt either
-            f = self.open(TESTFN, 'rb')
-            try:
-                for line in f:
-                    pass
-                try:
-                    f.readline()
-                    f.readinto(buf)
-                    f.read()
-                    f.readlines()
-                except ValueError:
-                    self.fail("read* failed after next() consumed file")
-            finally:
-                f.close()
+                self.fail("read* failed after next() consumed file")
         finally:
-            os.unlink(TESTFN)
+            f.close()
 
 class COtherFileTests(OtherFileTests, unittest.TestCase):
     open = io.open
@@ -319,11 +319,5 @@ class PyOtherFileTests(OtherFileTests, unittest.TestCase):
     open = staticmethod(pyio.open)
 
 
-def tearDownModule():
-    # Historically, these tests have been sloppy about removing TESTFN.
-    # So get rid of it no matter what.
-    if os.path.exists(TESTFN):
-        os.unlink(TESTFN)
-
 if __name__ == '__main__':
     unittest.main()