winsize refuses fewer than 2 rows, saying so, and its range reads 1x2 to 4096x4096 as the docs say

`winsize 20 1` was taken and quietly raised to 2 rows, so the write
succeeded with a size other than the one asked for. The range refusal
also said "1x1 to 4096x4096", although fs.md says at least 2 rows. One row
is now refused with "invalid winsize: at least 2 rows", and the range
text starts at 1x2. size already refused anything under 20x6 with a text
that names it.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 8 insertions, 3 deletions

diff --git a/test/fs.py b/test/fs.py
index 10802e19..a1e2ae79 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -436,9 +436,14 @@ def run_file(binary):
             assert run(client, term, b'fi\n') == b'error not run\n'  # a syntax error runs nothing
             assert run(client, term, b"echo 'open\n") == b'error not run\n'  # nor does an open quote
             assert run(client, term, b'true\n') == b'exit 0\n'  # ...and the shell is clear after
-            # A pty asked for one row gets two: one loses the prompt's input
-            # mark, and the shell would read busy for ever.
-            client.write(f'/pane/{term}/pty/ctl', b'winsize 20 1\n')
+            # A pty is not given one row (it loses the prompt's input mark,
+            # and the shell would read busy for ever): refused, and said.
+            try:
+                client.write(f'/pane/{term}/pty/ctl', b'winsize 20 1\n')
+                raise AssertionError('winsize 20 1 was taken')
+            except OSError as refused:
+                assert 'at least 2 rows' in str(refused), refused
+            client.write(f'/pane/{term}/pty/ctl', b'winsize 20 2\n')
             time.sleep(.5)
             assert run(client, term, b'true\n') == b'exit 0\n'
             assert client.read(f'/pane/{term}/pty/ctl').split()[2] == b'2', client.read(f'/pane/{term}/pty/ctl')