ASCII output for --parallel report lines (#2164)

* Add SpinnerMessage helper class

This class provides a single interface for spinner strings where we
ideally want to report Unicode but want to fall back to ASCII when the
terminal doesn't support it.

* Add ASCII messages for OK/FAIL/SKIP lines

Fixes #1421.

4 files changed, 46 insertions, 21 deletions

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 14d9bbad..d91bef34 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -20,6 +20,7 @@ Bastien Vallet
 Benoit Pierre
 Bernat Gabor
 Brett Langdon
+Brett Smith
 Bruno Oliveira
 Carl Meyer
 Charles Brunet
diff --git a/docs/changelog/1421.bugfix.rst b/docs/changelog/1421.bugfix.rst
new file mode 100644
index 00000000..8e0a5ff5
--- /dev/null
+++ b/docs/changelog/1421.bugfix.rst
@@ -0,0 +1 @@
+``--parallel`` reports now show ASCII OK/FAIL/SKIP lines when full Unicode output is not available - by :user:`brettcs`
diff --git a/src/tox/util/spinner.py b/src/tox/util/spinner.py
index 523a0c49..ee225895 100644
--- a/src/tox/util/spinner.py
+++ b/src/tox/util/spinner.py
@@ -5,7 +5,7 @@ from __future__ import absolute_import, unicode_literals
 import os
 import sys
 import threading
-from collections import OrderedDict
+from collections import OrderedDict, namedtuple
 from datetime import datetime
 
 import py
@@ -19,34 +19,32 @@ if os.name == "nt":
         _fields_ = [("size", ctypes.c_int), ("visible", ctypes.c_byte)]
 
 
-def _file_support_encoding(chars, file):
-    encoding = getattr(file, "encoding", None)
-    if encoding is not None:
-        for char in chars:
-            try:
-                char.encode(encoding)
-            except UnicodeEncodeError:
-                break
+_BaseMessage = namedtuple("_BaseMessage", ["unicode_msg", "ascii_msg"])
+
+
+class SpinnerMessage(_BaseMessage):
+    def for_file(self, file):
+        try:
+            self.unicode_msg.encode(file.encoding)
+        except (AttributeError, TypeError, UnicodeEncodeError):
+            return self.ascii_msg
         else:
-            return True
-    return False
+            return self.unicode_msg
 
 
 class Spinner(object):
     CLEAR_LINE = "\033[K"
     max_width = 120
-    UNICODE_FRAMES = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"]
-    ASCII_FRAMES = ["|", "-", "+", "x", "*"]
+    FRAMES = SpinnerMessage("⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏", "|-+x*")
+    OK_FLAG = SpinnerMessage("✔ OK", "[ OK ]")
+    FAIL_FLAG = SpinnerMessage("✖ FAIL", "[FAIL]")
+    SKIP_FLAG = SpinnerMessage("⚠ SKIP", "[SKIP]")
 
     def __init__(self, enabled=True, refresh_rate=0.1):
         self.refresh_rate = refresh_rate
         self.enabled = enabled
         self._file = sys.stdout
-        self.frames = (
-            self.UNICODE_FRAMES
-            if _file_support_encoding(self.UNICODE_FRAMES, sys.stdout)
-            else self.ASCII_FRAMES
-        )
+        self.frames = self.FRAMES.for_file(self._file)
         self.stream = py.io.TerminalWriter(file=self._file)
         self._envs = OrderedDict()
         self._frame_index = 0
@@ -105,13 +103,13 @@ class Spinner(object):
         self._envs[name] = datetime.now()
 
     def succeed(self, key):
-        self.finalize(key, "✔ OK", green=True)
+        self.finalize(key, self.OK_FLAG.for_file(self._file), green=True)
 
     def fail(self, key):
-        self.finalize(key, "✖ FAIL", red=True)
+        self.finalize(key, self.FAIL_FLAG.for_file(self._file), red=True)
 
     def skip(self, key):
-        self.finalize(key, "⚠ SKIP", white=True)
+        self.finalize(key, self.SKIP_FLAG.for_file(self._file), white=True)
 
     def finalize(self, key, status, **kwargs):
         start_at = self._envs[key]
diff --git a/tests/unit/util/test_spinner.py b/tests/unit/util/test_spinner.py
index 7c64ac45..2511d584 100644
--- a/tests/unit/util/test_spinner.py
+++ b/tests/unit/util/test_spinner.py
@@ -113,6 +113,31 @@ def test_spinner_stdout_not_unicode(mocker, capfd):
     assert all(f in written for f in spin.frames)
 
 
+@freeze_time("2012-01-14")
+def test_spinner_report_not_unicode(mocker, capfd):
+    stdout = mocker.patch("tox.util.spinner.sys.stdout")
+    stdout.encoding = "ascii"
+    # Disable color to simplify parsing output strings
+    stdout.isatty = lambda: False
+    with spinner.Spinner(refresh_rate=100) as spin:
+        spin.stream.write(os.linesep)
+        spin.add("ok!")
+        spin.add("fail!")
+        spin.add("skip!")
+        spin.succeed("ok!")
+        spin.fail("fail!")
+        spin.skip("skip!")
+    lines = "".join(args[0] for args, _ in stdout.write.call_args_list).split(os.linesep)
+    del lines[0]
+    expected = [
+        "\r{}[ OK ] ok! in 0.0 seconds".format(spin.CLEAR_LINE),
+        "\r{}[FAIL] fail! in 0.0 seconds".format(spin.CLEAR_LINE),
+        "\r{}[SKIP] skip! in 0.0 seconds".format(spin.CLEAR_LINE),
+        "\r{}".format(spin.CLEAR_LINE),
+    ]
+    assert lines == expected
+
+
 @pytest.mark.parametrize(
     "seconds, expected",
     [