Use UTF-8 encoding when parsing pyproject.toml (#1940)

src/tox/_pytestplugin.py

@@ -491,7 +491,14 @@ def create_files(base, filedefs):
             create_files(base.ensure(key, dir=1), value)
         elif isinstance(value, six.string_types):
             s = textwrap.dedent(value)
-            base.join(key).write(s)
+
+            if not isinstance(s, six.text_type):
+                if not isinstance(s, six.binary_type):
+                    s = str(s)
+                else:
+                    s = six.ensure_text(s)
+
+            base.join(key).write_text(s, encoding="UTF-8")
 
 
 @pytest.fixture()

src/tox/config/__init__.py

@@ -1,6 +1,7 @@
 from __future__ import print_function
 
 import argparse
+import io
 import itertools
 import json
 import os
@@ -303,7 +304,7 @@ def parseconfig(args, plugins=()):
 
 
 def get_py_project_toml(path):
-    with open(str(path)) as file_handler:
+    with io.open(str(path), encoding="UTF-8") as file_handler:
         config_data = toml.load(file_handler)
         return config_data
 

tests/unit/config/test_config.py

@@ -1,3 +1,4 @@
+# coding=utf-8
 import os
 import re
 import sys
@@ -3556,7 +3557,10 @@ def test_config_via_pyproject_legacy(initproj):
     initproj(
         "config_via_pyproject_legacy-0.5",
         filedefs={
-            "pyproject.toml": '''
+            "pyproject.toml": u'''
+                [project]
+                description = "Factory ⸻ A code generator 🏭"
+                authors = [{name = "Łukasz Langa"}]
                 [tool.tox]
                 legacy_tox_ini = """
                 [tox]