Fall back to `sys.__stderr__` on non-Windows OS to get size

This fixes the "pipe" bug, where we could not determine the available size correctly when the output of Rich is piped to another process

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Fall back to `sys.__stderr__` on POSIX systems when trying to get the terminal size (fix issues when Rich is piped to another process)
+
 ## [12.2.0] - 2022-04-05
 
 ### Changed

CONTRIBUTORS.md

@@ -27,6 +27,7 @@ The following people have contributed to the development of Rich:
 - [Nathan Page](https://github.com/nathanrpage97)
 - [Avi Perl](https://github.com/avi-perl)
 - [Laurent Peuch](https://github.com/psycojoker)
+- [Olivier Philippon](https://github.com/DrBenton)
 - [Kylian Point](https://github.com/p0lux)
 - [Kyle Pollina](https://github.com/kylepollina)
 - [Clément Robert](https://github.com/neutrinoceros)

rich/console.py

@@ -1102,12 +1102,16 @@ class Console:
             except OSError:  # Probably not a terminal
                 pass
         else:
-            try:
-                width, height = os.get_terminal_size(sys.__stdin__.fileno())
-            except (AttributeError, ValueError, OSError):
+            posix_std_descriptors = (
+                sys.__stdin__,  # try this one first...
+                sys.__stdout__,  # ...then that one...
+                sys.__stderr__,  # ...and ultimately try to fall back to this one
+            )
+            for descriptor in posix_std_descriptors:
                 try:
-                    width, height = os.get_terminal_size(sys.__stdout__.fileno())
-                except (AttributeError, ValueError, OSError):
+                    width, height = os.get_terminal_size(descriptor.fileno())
+                    break
+                except (AttributeError, ValueError, OSError) as err:
                     pass
 
         columns = self._environ.get("COLUMNS")

tests/test_console.py

@@ -3,7 +3,8 @@ import io
 import os
 import sys
 import tempfile
-from typing import Optional
+from typing import Optional, Tuple, Type, Union
+from unittest import mock
 
 import pytest
 
@@ -122,6 +123,48 @@ def test_size():
     assert w == 99 and h == 101
 
 
+@pytest.mark.parametrize(
+    "is_windows,no_descriptor_size,stdin_size,stdout_size,stderr_size,expected_size",
+    [
+        # on Windows we'll use `os.get_terminal_size()` without arguments...
+        (True, (133, 24), ValueError, ValueError, ValueError, (133, 24)),
+        (False, (133, 24), ValueError, ValueError, ValueError, (80, 25)),
+        # ...while on other OS we'll try to pass stdin, then stdout, then stderr to it:
+        (False, ValueError, (133, 24), ValueError, ValueError, (133, 24)),
+        (False, ValueError, ValueError, (133, 24), ValueError, (133, 24)),
+        (False, ValueError, ValueError, ValueError, (133, 24), (133, 24)),
+        (False, ValueError, ValueError, ValueError, ValueError, (80, 25)),
+    ],
+)
+@mock.patch("rich.console.os.get_terminal_size")
+def test_size_can_fall_back_to_std_descriptors(
+    get_terminal_size_mock: mock.MagicMock,
+    is_windows: bool,
+    no_descriptor_size: Union[Tuple[int, int], Type[ValueError]],
+    stdin_size: Union[Tuple[int, int], Type[ValueError]],
+    stdout_size: Union[Tuple[int, int], Type[ValueError]],
+    stderr_size: Union[Tuple[int, int], Type[ValueError]],
+    expected_size,
+):
+    def get_terminal_size_mock_impl(fileno: int = None) -> Tuple[int, int]:
+        value = {
+            None: no_descriptor_size,
+            sys.__stdin__.fileno(): stdin_size,
+            sys.__stdout__.fileno(): stdout_size,
+            sys.__stderr__.fileno(): stderr_size,
+        }[fileno]
+        if value is ValueError:
+            raise value
+        return value
+
+    get_terminal_size_mock.side_effect = get_terminal_size_mock_impl
+
+    console = Console(legacy_windows=False)
+    with mock.patch("rich.console.WINDOWS", new=is_windows):
+        w, h = console.size
+    assert (w, h) == expected_size
+
+
 def test_repr():
     console = Console()
     assert isinstance(repr(console), str)