Fix _is_setup_py for files encoded differently than locale

testing/test_doctest.py

@@ -5,6 +5,7 @@ import pytest
 from _pytest.compat import MODULE_NOT_FOUND_ERROR
 from _pytest.doctest import _get_checker
 from _pytest.doctest import _is_mocked
+from _pytest.doctest import _is_setup_py
 from _pytest.doctest import _patch_unwrap_mock_aware
 from _pytest.doctest import DoctestItem
 from _pytest.doctest import DoctestModule
@@ -1487,3 +1488,27 @@ def test_warning_on_unwrap_of_broken_object(stop):
             with pytest.raises(KeyError):
                 inspect.unwrap(bad_instance, stop=stop)
     assert inspect.unwrap.__module__ == "inspect"
+
+
+def test_is_setup_py_not_named_setup_py(tmpdir):
+    not_setup_py = tmpdir.join("not_setup.py")
+    not_setup_py.write('from setuptools import setup; setup(name="foo")')
+    assert not _is_setup_py(not_setup_py)
+
+
+@pytest.mark.parametrize("mod", ("setuptools", "distutils.core"))
+def test_is_setup_py_is_a_setup_py(tmpdir, mod):
+    setup_py = tmpdir.join("setup.py")
+    setup_py.write('from {} import setup; setup(name="foo")'.format(mod))
+    assert _is_setup_py(setup_py)
+
+
+@pytest.mark.parametrize("mod", ("setuptools", "distutils.core"))
+def test_is_setup_py_different_encoding(tmpdir, mod):
+    setup_py = tmpdir.join("setup.py")
+    contents = (
+        "# -*- coding: cp1252 -*-\n"
+        'from {} import setup; setup(name="foo", description="€")\n'.format(mod)
+    )
+    setup_py.write_binary(contents.encode("cp1252"))
+    assert _is_setup_py(setup_py)