[3.9] bpo-41069: Make TESTFN and the CWD for tests containing non-ascii characters. (GH-21035). (GH-21156)

(cherry picked from commit 700cfa8c90)

Lib/test/test_gzip.py

@@ -328,8 +328,15 @@ class TestGzip(BaseTest):
             cmByte = fRead.read(1)
             self.assertEqual(cmByte, b'\x08') # deflate
 
+            try:
+                expectedname = self.filename.encode('Latin-1') + b'\x00'
+                expectedflags = b'\x08' # only the FNAME flag is set
+            except UnicodeEncodeError:
+                expectedname = b''
+                expectedflags = b'\x00'
+
             flagsByte = fRead.read(1)
-            self.assertEqual(flagsByte, b'\x08') # only the FNAME flag is set
+            self.assertEqual(flagsByte, expectedflags)
 
             mtimeBytes = fRead.read(4)
             self.assertEqual(mtimeBytes, struct.pack('<i', mtime)) # little-endian
@@ -344,9 +351,8 @@ class TestGzip(BaseTest):
             # RFC 1952 specifies that this is the name of the input file, if any.
             # However, the gzip module defaults to storing the name of the output
             # file in this field.
-            expected = self.filename.encode('Latin-1') + b'\x00'
-            nameBytes = fRead.read(len(expected))
-            self.assertEqual(nameBytes, expected)
+            nameBytes = fRead.read(len(expectedname))
+            self.assertEqual(nameBytes, expectedname)
 
             # Since no other flags were set, the header ends here.
             # Rather than process the compressed data, let's seek to the trailer.
@@ -358,6 +364,10 @@ class TestGzip(BaseTest):
             isizeBytes = fRead.read(4)
             self.assertEqual(isizeBytes, struct.pack('<i', len(data1)))
 
+    def test_metadata_ascii_name(self):
+        self.filename = support.TESTFN_ASCII
+        self.test_metadata()
+
     def test_compresslevel_metadata(self):
         # see RFC 1952: http://www.faqs.org/rfcs/rfc1952.html
         # specifically, discussion of XFL in section 2.3.1