Simplify the assertExpected method (pytorch#2965)

* Simplify the ACCEPT=True logic in assertExpected().

* Separate the expected filename estimation from assertExpected

test/common_utils.py

@@ -88,24 +88,7 @@ def is_iterable(obj):
 class TestCase(unittest.TestCase):
     precision = 1e-5
 
-    def assertExpected(self, output, subname=None, prec=None, strip_suffix=None):
-        r"""
-        Test that a python value matches the recorded contents of a file
-        derived from the name of this test and subname.  The value must be
-        pickable with `torch.save`. This file
-        is placed in the 'expect' directory in the same directory
-        as the test script. You can automatically update the recorded test
-        output using --accept.
-
-        If you call this multiple times in a single function, you must
-        give a unique subname each time.
-
-        strip_suffix allows different tests that expect similar numerics, e.g.
-        "test_xyz_cuda" and "test_xyz_cpu", to use the same pickled data.
-        test_xyz_cuda would pass strip_suffix="_cuda", test_xyz_cpu would pass
-        strip_suffix="_cpu", and they would both use a data file name based on
-        "test_xyz".
-        """
+    def _get_expected_file(self, subname=None, strip_suffix=None):
         def remove_prefix_suffix(text, prefix, suffix):
             if text.startswith(prefix):
                 text = text[len(prefix):]
@@ -128,33 +111,41 @@ def remove_prefix_suffix(text, prefix, suffix):
             subname_output = " ({})".format(subname)
         expected_file += "_expect.pkl"
 
-        def accept_output(update_type):
-            print("Accepting {} for {}{}:\n\n{}".format(update_type, munged_id, subname_output, output))
+        if not ACCEPT and not os.path.exists(expected_file):
+            raise RuntimeError(
+                ("No expect file exists for {}{}; to accept the current output, run:\n"
+                 "python {} {} --accept").format(munged_id, subname_output, __main__.__file__, munged_id))
+
+        return expected_file
+
+    def assertExpected(self, output, subname=None, prec=None, strip_suffix=None):
+        r"""
+        Test that a python value matches the recorded contents of a file
+        derived from the name of this test and subname.  The value must be
+        pickable with `torch.save`. This file
+        is placed in the 'expect' directory in the same directory
+        as the test script. You can automatically update the recorded test
+        output using --accept.
+
+        If you call this multiple times in a single function, you must
+        give a unique subname each time.
+
+        strip_suffix allows different tests that expect similar numerics, e.g.
+        "test_xyz_cuda" and "test_xyz_cpu", to use the same pickled data.
+        test_xyz_cuda would pass strip_suffix="_cuda", test_xyz_cpu would pass
+        strip_suffix="_cpu", and they would both use a data file name based on
+        "test_xyz".
+        """
+        expected_file = self._get_expected_file(subname, strip_suffix)
+
+        if ACCEPT:
+            print("Accepting updated output for {}:\n\n{}".format(os.path.basename(expected_file), output))
             torch.save(output, expected_file)
             MAX_PICKLE_SIZE = 50 * 1000  # 50 KB
             binary_size = os.path.getsize(expected_file)
             self.assertTrue(binary_size <= MAX_PICKLE_SIZE)
-
-        try:
-            expected = torch.load(expected_file)
-        except IOError as e:
-            if e.errno != errno.ENOENT:
-                raise
-            elif ACCEPT:
-                accept_output("output")
-                return
-            else:
-                raise RuntimeError(
-                    ("I got this output for {}{}:\n\n{}\n\n"
-                     "No expect file exists; to accept the current output, run:\n"
-                     "python {} {} --accept").format(munged_id, subname_output, output, __main__.__file__, munged_id))
-
-        if ACCEPT:
-            try:
-                self.assertEqual(output, expected, prec=prec)
-            except Exception:
-                accept_output("updated output")
         else:
+            expected = torch.load(expected_file)
             self.assertEqual(output, expected, prec=prec)
 
     def assertEqual(self, x, y, prec=None, message='', allow_inf=False):