#1223 resolve unicode spinner error (#1225)

Author: gaborbernat

docs/changelog/1223.bugfix.rst

@@ -0,0 +1 @@
+Spinner fails in CI on ``UnicodeDecodeError`` - by :user:`gaborbernat`

src/tox/util/spinner.py

@@ -25,7 +25,7 @@ def _file_support_encoding(chars, file):
         for char in chars:
             try:
                 char.encode(encoding)
-            except UnicodeDecodeError:
+            except UnicodeEncodeError:
                 break
         else:
             return True

tests/unit/util/test_spinner.py

@@ -96,3 +96,13 @@ def test_spinner_long_text(capfd, monkeypatch):
     lines = out.split("\n")
     del lines[0]
     assert lines == expected
+
+
+def test_spinner_stdout_not_unicode(capfd, monkeypatch):
+    monkeypatch.setattr(sys.stdout, "encoding", "ascii")
+    with spinner.Spinner(refresh_rate=100) as spin:
+        for _ in range(len(spin.frames)):
+            spin.render_frame()
+    out, err = capfd.readouterr()
+    assert not err
+    assert all(f in out for f in spin.frames)