Fix unicode/test issues with compass filter.

src/webassets/filter/compass.py

@@ -31,6 +31,7 @@
 import tempfile
 import shutil
 import subprocess
+from io import open
 from webassets import six
 
 from webassets.exceptions import FilterError
@@ -233,7 +234,7 @@ def open(self, out, source_path, **kw):
 
             guessed_outputfilename = path.splitext(path.basename(source_path))[0]
             guessed_outputfilepath = path.join(tempout, guessed_outputfilename)
-            output_file = open("%s.css" % guessed_outputfilepath)
+            output_file = open("%s.css" % guessed_outputfilepath, encoding='utf-8')
             if config.get('sourcemap'):
                 sourcemap_file = open("%s.css.map" % guessed_outputfilepath)
                 sourcemap_output_filepath = path.join(
@@ -245,7 +246,7 @@ def open(self, out, source_path, **kw):
                 sourcemap_output_file = open(sourcemap_output_filepath, 'w')
                 sourcemap_output_file.write(sourcemap_file.read())
             try:
-                contents = output_file.read().decode('utf-8')
+                contents = output_file.read()
                 out.write(contents)
             finally:
                 output_file.close()

tests/test_filters.py

@@ -1114,7 +1114,11 @@ def test_compass_with_unicode(self):
 
         # It's very hard to test this with doctest_match
         # And by asserting that it's in the content this test is proven
-        assert """content: "\xc3\xa1\xc3\xa9";""" in self.get('out.css')
+        from webassets.six import PY3
+        if PY3:
+            assert """content: "áé";""" in self.get('out.css')
+        else:
+            assert """content: "\xc3\xa1\xc3\xa9";""" in self.get('out.css')
 
     def test_images_dir(self):
         # [bug] Make sure the compass plugin can reference images. It expects