Decode all bytes strings in extra text.

pytest_html/plugin.py

@@ -198,6 +198,8 @@ class HTMLReport(object):
 
             elif extra.get('format') == extras.FORMAT_TEXT:
                 content = extra.get('content')
+                if isinstance(content, bytes):
+                    content = content.decode("utf-8")
                 if self.self_contained:
                     href = data_uri(content)
                 else:

testing/test_pytest_html.py

@@ -238,7 +238,8 @@ class TestHTML:
 
     @pytest.mark.parametrize('content, encoded', [
         ("u'\u0081'", 'woE='),
-        ("'foo'", 'Zm9v')])
+        ("'foo'", 'Zm9v'),
+        ("b'\\xe2\\x80\\x93'", "4oCT")])
     def test_extra_text(self, testdir, content, encoded):
         testdir.makeconftest("""
             import pytest
@@ -325,7 +326,8 @@ class TestHTML:
         src = 'data:{0};base64,{1}'.format(mime_type, content)
         assert '<img src="{0}"/>'.format(src) in html
 
-    @pytest.mark.parametrize('content', [("u'\u0081'"), ("'foo'")])
+    @pytest.mark.parametrize('content', [("u'\u0081'"), ("'foo'"),
+                                         ("b'\\xe2\\x80\\x93'")])
     def test_extra_text_separated(self, testdir, content):
         testdir.makeconftest("""
             import pytest