Fix mypy pretty output within a pty

python · msullivan · Dec 14, 2019 · Dec 13, 2019 · Dec 13, 2019 · Dec 13, 2019
commit 9dccccaf68924a89f5d01d2a76a671a5dc7f3918
diff --git a/mypy/test/testutil.py b/mypy/test/testutil.py
@@ -0,0 +1,12 @@
+import os
+from unittest import mock, TestCase
+
+from mypy.util import get_terminal_width
+
+
+class TestGetTerminalSize(TestCase):
+    def test_get_terminal_size_in_pty_defaults_to_80(self) -> None:
+        # when run using a pty, `os.get_terminal_size()` returns `0, 0`
+        ret = os.terminal_size((0, 0))
+        with mock.patch.object(os, 'get_terminal_size', return_value=ret):
+            assert get_terminal_width() == 80
diff --git a/mypy/util.py b/mypy/util.py
@@ -424,9 +424,12 @@ def get_terminal_width() -> int:
     """Get current terminal width if possible, otherwise return the default one."""
     try:
         cols, _ = os.get_terminal_size()
-        return cols
     except OSError:
         return DEFAULT_COLUMNS
+    else:
+        if cols == 0:
+            return DEFAULT_COLUMNS
+        return cols
 
 
 def soft_wrap(msg: str, max_len: int, first_offset: int,