Switch to a much simpler test. Interrupting processes encountered some issues

with with Windows, that will be addressed in ipykernel (which will grow its own test).

IPython/core/tests/test_debugger.py

@@ -1,298 +1,248 b''
 """Tests for debugging machinery.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import signal
 import sys
 import time
 import warnings
 from tempfile import NamedTemporaryFile
 from subprocess import check_output, CalledProcessError, PIPE
 import subprocess
+from unittest.mock import patch
+import builtins
 
 import nose.tools as nt
 
 from IPython.core import debugger
 
 #-----------------------------------------------------------------------------
 # Helper classes, from CPython's Pdb test suite
 #-----------------------------------------------------------------------------
 
 class _FakeInput(object):
     """
     A fake input stream for pdb's interactive debugger.  Whenever a
     line is read, print it (to simulate the user typing it), and then
     return it.  The set of lines to return is specified in the
     constructor; they should not have trailing newlines.
     """
     def __init__(self, lines):
         self.lines = iter(lines)
 
     def readline(self):
         line = next(self.lines)
         print(line)
         return line+'\n'
 
 class PdbTestInput(object):
     """Context manager that makes testing Pdb in doctests easier."""
 
     def __init__(self, input):
         self.input = input
 
     def __enter__(self):
         self.real_stdin = sys.stdin
         sys.stdin = _FakeInput(self.input)
 
     def __exit__(self, *exc):
         sys.stdin = self.real_stdin
 
 #-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 
 def test_longer_repr():
     from reprlib import repr as trepr
     
     a = '1234567890'* 7
     ar = "'1234567890123456789012345678901234567890123456789012345678901234567890'"
     a_trunc = "'123456789012...8901234567890'"
     nt.assert_equal(trepr(a), a_trunc)
     # The creation of our tracer modifies the repr module's repr function
     # in-place, since that global is used directly by the stdlib's pdb module.
     with warnings.catch_warnings():
         warnings.simplefilter('ignore', DeprecationWarning)
         debugger.Tracer()
     nt.assert_equal(trepr(a), ar)
 
 def test_ipdb_magics():
     '''Test calling some IPython magics from ipdb.
 
     First, set up some test functions and classes which we can inspect.
 
     >>> class ExampleClass(object):
     ...    """Docstring for ExampleClass."""
     ...    def __init__(self):
     ...        """Docstring for ExampleClass.__init__"""
     ...        pass
     ...    def __str__(self):
     ...        return "ExampleClass()"
 
     >>> def example_function(x, y, z="hello"):
     ...     """Docstring for example_function."""
     ...     pass
 
     >>> old_trace = sys.gettrace()
 
     Create a function which triggers ipdb.
 
     >>> def trigger_ipdb():
     ...    a = ExampleClass()
     ...    debugger.Pdb().set_trace()
 
     >>> with PdbTestInput([
     ...    'pdef example_function',
     ...    'pdoc ExampleClass',
     ...    'up',
     ...    'down',
     ...    'list',
     ...    'pinfo a',
     ...    'll',
     ...    'continue',
     ... ]):
     ...     trigger_ipdb()
     --Return--
     None
     > <doctest ...>(3)trigger_ipdb()
           1 def trigger_ipdb():
           2    a = ExampleClass()
     ----> 3    debugger.Pdb().set_trace()
     <BLANKLINE>
     ipdb> pdef example_function
      example_function(x, y, z='hello')
      ipdb> pdoc ExampleClass
     Class docstring:
         Docstring for ExampleClass.
     Init docstring:
         Docstring for ExampleClass.__init__
     ipdb> up
     > <doctest ...>(11)<module>()
           7    'pinfo a',
           8    'll',
           9    'continue',
          10 ]):
     ---> 11     trigger_ipdb()
     <BLANKLINE>
     ipdb> down
     None
     > <doctest ...>(3)trigger_ipdb()
           1 def trigger_ipdb():
           2    a = ExampleClass()
     ----> 3    debugger.Pdb().set_trace()
     <BLANKLINE>
     ipdb> list
           1 def trigger_ipdb():
           2    a = ExampleClass()
     ----> 3    debugger.Pdb().set_trace()
     <BLANKLINE>
     ipdb> pinfo a
     Type:           ExampleClass
     String form:    ExampleClass()
     Namespace:      Local...
     Docstring:      Docstring for ExampleClass.
     Init docstring: Docstring for ExampleClass.__init__
     ipdb> ll
           1 def trigger_ipdb():
           2    a = ExampleClass()
     ----> 3    debugger.Pdb().set_trace()
     <BLANKLINE>
     ipdb> continue
     
     Restore previous trace function, e.g. for coverage.py    
     
     >>> sys.settrace(old_trace)
     '''
 
 def test_ipdb_magics2():
     '''Test ipdb with a very short function.
     
     >>> old_trace = sys.gettrace()
 
     >>> def bar():
     ...     pass
 
     Run ipdb.
 
     >>> with PdbTestInput([
     ...    'continue',
     ... ]):
     ...     debugger.Pdb().runcall(bar)
     > <doctest ...>(2)bar()
           1 def bar():
     ----> 2    pass
     <BLANKLINE>
     ipdb> continue
     
     Restore previous trace function, e.g. for coverage.py    
     
     >>> sys.settrace(old_trace)
     '''
 
 def can_quit():
     '''Test that quit work in ipydb
 
     >>> old_trace = sys.gettrace()
 
     >>> def bar():
     ...     pass
 
     >>> with PdbTestInput([
     ...    'quit',
     ... ]):
     ...     debugger.Pdb().runcall(bar)
     > <doctest ...>(2)bar()
             1 def bar():
     ----> 2    pass
     <BLANKLINE>
     ipdb> quit
 
     Restore previous trace function, e.g. for coverage.py
 
     >>> sys.settrace(old_trace)
     '''
 
 
 def can_exit():
     '''Test that quit work in ipydb
 
     >>> old_trace = sys.gettrace()
 
     >>> def bar():
     ...     pass
 
     >>> with PdbTestInput([
     ...    'exit',
     ... ]):
     ...     debugger.Pdb().runcall(bar)
     > <doctest ...>(2)bar()
             1 def bar():
     ----> 2    pass
     <BLANKLINE>
     ipdb> exit
 
     Restore previous trace function, e.g. for coverage.py
 
     >>> sys.settrace(old_trace)
     '''
 
 
-interruptible_debugger = """\
-import sys
-import threading
-import time
-from os import _exit
-from bdb import BdbQuit
-
-from IPython.core.debugger import set_trace
-
-# Timeout if the interrupt doesn't happen:
-def timeout():
-    time.sleep(5)
-    _exit(7)
-threading.Thread(target=timeout, daemon=True).start()
-
-def break_handler(*args):
-    print("BREAK!")
-    raise KeyboardInterrupt()
-
-def main():
-    import signal
-    signal.signal(signal.SIGBREAK, break_handler)
-    set_trace()
-
-if __name__ == '__main__':
-    try:
-        print("Starting debugger...")
-        main()
-        print("Debugger exited without error.")
-    except (KeyboardInterrupt, BdbQuit):
-        print("Caught KeyboardInterrupt or BdbQuit, PASSED")
-    except Exception as e:
-        print("Got wrong exception...")
-        raise e
-"""
-
-
 def test_interruptible_core_debugger():
     """The debugger can be interrupted.
-    
-    See https://stackoverflow.com/a/35792192 for details on Windows.
+
+    The presumption is there is some mechanism that causes a KeyboardInterrupt
+    (this is implemented in ipykernel).  We want to ensure the
+    KeyboardInterrupt cause debugging to cease.
     """
-    with NamedTemporaryFile("w", delete=False) as f:
-        f.write(interruptible_debugger)
-        f.flush()
-    start = time.time()
-    
-    p = subprocess.Popen([sys.executable, "-u", f.name],
-                         creationflags=subprocess.CREATE_NEW_PROCESS_GROUP, # TODO disable on posix
-                         encoding=sys.getdefaultencoding(),
-                         stderr=PIPE, stdout=PIPE)
-    time.sleep(1)  # wait for it to hit pdb
-    if sys.platform == "win32":
-        # Yes, this has to happen once. I have no idea why.
-        p.send_signal(signal.CTRL_BREAK_EVENT)
-        p.send_signal(signal.CTRL_BREAK_EVENT)
-    else:
-        p.send_signal(signal.SIGINT)
-    exit_code = p.wait()
-    stdout = p.stdout.read()
-    stderr = p.stderr.read()
-    print("STDOUT", stdout, file=sys.__stderr__)
-    print("STDERR", stderr, file=sys.__stderr__)
-    assert exit_code == 0
-    print("SUCCESS!", file=sys.__stderr__)
-    # Make sure it exited cleanly, and quickly:
-    end = time.time()
-    assert end - start < 2  # timeout is 5 seconds
-    assert "PASSED" in stdout
  No newline at end of file
+    def raising_input(msg=""):
+        raise KeyboardInterrupt()
+
+    with patch.object(builtins, "input", raising_input):
+        debugger.set_trace()
+        # The way this test will fail is by set_trace() never exiting,
+        # resulting in a timeout by the test runner. The alternative
+        # implementation would involve a subprocess, but that adds issues with
+        # interrupting subprocesses that are rather complex, so it's simpler
+        # just to do it this way.