ensure unix_console.{prepare,restore} maintain state properly for when signal fails (ie in a thread), test

Author: bdkearns

pyrepl/unix_console.py

@@ -393,6 +393,7 @@ def restore(self):
 
         if hasattr(self, 'old_sigwinch'):
             signal.signal(signal.SIGWINCH, self.old_sigwinch)
+            del self.old_sigwinch
 
     def __sigwinch(self, signum, frame):
         self.height, self.width = self.getheightwidth()

testing/test_bugs.py

@@ -44,3 +44,29 @@ def test_cmd_instantiation_crash():
         ('accept', [''])
     ]
     read_spec(spec, HistoricalTestReader)
+
+
+def test_signal_failure(monkeypatch):
+    import os
+    import pty
+    import signal
+    from pyrepl.unix_console import UnixConsole
+
+    def failing_signal(a, b):
+        raise ValueError
+
+    def really_failing_signal(a, b):
+        raise AssertionError
+
+    mfd, sfd = pty.openpty()
+    try:
+        c = UnixConsole(sfd, sfd)
+        c.prepare()
+        c.restore()
+        monkeypatch.setattr(signal, 'signal', failing_signal)
+        c.prepare()
+        monkeypatch.setattr(signal, 'signal', really_failing_signal)
+        c.restore()
+    finally:
+        os.close(mfd)
+        os.close(sfd)