fix(tests/unit): Update tests to be endian safe

This updates `test_path_to_display` and `test_str_to_display__encoding`
to use the endian safe expected result instead of the hardcoded one.

This fixes https://github.com/pypa/pip/issues/7921

tests/unit/test_compat.py

@@ -2,6 +2,7 @@
 
 import locale
 import os
+import sys
 
 import pytest
 
@@ -91,8 +92,13 @@ def test_str_to_display__decode_error(monkeypatch, caplog):
     # Encode with an incompatible encoding.
     data = u'ab'.encode('utf-16')
     actual = str_to_display(data)
+    # Keep the expected value endian safe
+    if sys.byteorder == "little":
+        expected = "\\xff\\xfea\x00b\x00"
+    elif sys.byteorder == "big":
+        expected = "\\xfe\\xff\x00a\x00b"
 
-    assert actual == u'\\xff\\xfea\x00b\x00', (
+    assert actual == expected, (
         # Show the encoding for easier troubleshooting.
         'encoding: {!r}'.format(locale.getpreferredencoding())
     )

tests/unit/test_utils.py

@@ -375,6 +375,18 @@ def test_rmtree_retries_for_3sec(tmpdir, monkeypatch):
         rmtree('foo')
 
 
+if sys.byteorder == "little":
+    expected_byte_string = (
+        u"b'\\xff\\xfe/\\x00p\\x00a\\x00t\\x00h\\x00/"
+        "\\x00d\\x00\\xe9\\x00f\\x00'"
+    )
+elif sys.byteorder == "big":
+    expected_byte_string = (
+        u"b'\\xfe\\xff\\x00/\\x00p\\x00a\\x00t\\x00h\\"
+        "x00/\\x00d\\x00\\xe9\\x00f'"
+    )
+
+
 @pytest.mark.parametrize('path, fs_encoding, expected', [
     (None, None, None),
     # Test passing a text (unicode) string.
@@ -383,9 +395,7 @@ def test_rmtree_retries_for_3sec(tmpdir, monkeypatch):
     (u'/path/déf'.encode('utf-8'), 'utf-8', u'/path/déf'),
     # Test a bytes object with a character that can't be decoded.
     (u'/path/déf'.encode('utf-8'), 'ascii', u"b'/path/d\\xc3\\xa9f'"),
-    (u'/path/déf'.encode('utf-16'), 'utf-8',
-     u"b'\\xff\\xfe/\\x00p\\x00a\\x00t\\x00h\\x00/"
-     "\\x00d\\x00\\xe9\\x00f\\x00'"),
+    (u'/path/déf'.encode('utf-16'), 'utf-8', expected_byte_string),
 ])
 def test_path_to_display(monkeypatch, path, fs_encoding, expected):
     monkeypatch.setattr(sys, 'getfilesystemencoding', lambda: fs_encoding)