Fix metadata test fixture on Linux (#14)

* Add user prefix to metadata test fixture on Linux and handle when the Linux filesystem doesn't support extended attributes
* Bump test coverage targets

.github/codecov.yml

@@ -11,11 +11,11 @@ coverage:
   status:
     patch:
       default:
-        target: 90%
+        target: 95%
     project:
       default: false
       exif_stripper:
-        target: 90%
+        target: 95%
         paths:
           - "!tests/.*"
       tests:

tests/test_cli.py

@@ -2,13 +2,15 @@
 
 import platform
 import subprocess
+from getpass import getuser
 
 import pytest
 from PIL import Image
 
 from exif_stripper import cli
 
-RUNNING_ON_WINDOWS = platform.system() == 'Windows'
+RUNNING_ON = platform.system()
+RUNNING_ON_WINDOWS = RUNNING_ON == 'Windows'
 
 if not RUNNING_ON_WINDOWS:
     from xattr import xattr
@@ -29,8 +31,17 @@ def image_with_exif_data(tmp_path):
 @pytest.fixture
 def image_with_metadata(image_with_exif_data):
     """Fixture for an image with metadata."""
-    if not RUNNING_ON_WINDOWS:
-        xattr(image_with_exif_data).set('the.limit.does.not.exist', b'\x00')
+    if RUNNING_ON in ['Darwin', 'Linux']:
+        try:
+            xattr(image_with_exif_data).set(
+                f'{getuser()}.test_extended_attribute'
+                if RUNNING_ON == 'Linux'
+                else 'com.apple.macl',
+                b'\x00',
+            )
+        except OSError:  # pragma: nocover
+            # filesystem does not support extended attributes
+            pass
     return image_with_exif_data