TST: Restore original trace function

IPython/core/tests/test_debugger.py

@@ -1,574 +1,580 b''
 """Tests for debugging machinery.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import bdb
 import builtins
 import os
 import signal
 import subprocess
 import sys
 import time
 import warnings
 
 from subprocess import PIPE, CalledProcessError, check_output
 from tempfile import NamedTemporaryFile
 from textwrap import dedent
 from unittest.mock import patch
 
 from IPython.core import debugger
 from IPython.testing import IPYTHON_TESTING_TIMEOUT_SCALE
 from IPython.testing.decorators import skip_win32
 
 #-----------------------------------------------------------------------------
 # 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'"
     assert 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()
     assert 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)
     '''
 
 
 def test_interruptible_core_debugger():
     """The debugger can be interrupted.
 
     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.
     """
     def raising_input(msg="", called=[0]):
         called[0] += 1
         if called[0] == 1:
             raise KeyboardInterrupt()
         else:
             raise AssertionError("input() should only be called once!")
 
-    with patch.object(builtins, "input", raising_input):
-        debugger.InterruptiblePdb().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.
+    tracer_orig = sys.gettrace()
+    try:
+        with patch.object(builtins, "input", raising_input):
+            debugger.InterruptiblePdb().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.
+    finally:
+        # restore the original trace function
+        sys.settrace(tracer_orig)
+
 
 @skip_win32
 def test_xmode_skip():
     """that xmode skip frames
 
     Not as a doctest as pytest does not run doctests.
     """
     import pexpect
     env = os.environ.copy()
     env["IPY_TEST_SIMPLE_PROMPT"] = "1"
 
     child = pexpect.spawn(
         sys.executable, ["-m", "IPython", "--colors=nocolor"], env=env
     )
     child.timeout = 15 * IPYTHON_TESTING_TIMEOUT_SCALE
 
     child.expect("IPython")
     child.expect("\n")
     child.expect_exact("In [1]")
 
     block = dedent(
         """
     def f():
         __tracebackhide__ = True
         g()
 
     def g():
         raise ValueError
 
     f()
     """
     )
 
     for line in block.splitlines():
         child.sendline(line)
         child.expect_exact(line)
     child.expect_exact("skipping")
 
     block = dedent(
         """
     def f():
         __tracebackhide__ = True
         g()
 
     def g():
         from IPython.core.debugger import set_trace
         set_trace()
 
     f()
     """
     )
 
     for line in block.splitlines():
         child.sendline(line)
         child.expect_exact(line)
 
     child.expect("ipdb>")
     child.sendline("w")
     child.expect("hidden")
     child.expect("ipdb>")
     child.sendline("skip_hidden false")
     child.sendline("w")
     child.expect("__traceba")
     child.expect("ipdb>")
 
     child.close()
 
 
 skip_decorators_blocks = (
     """
     def helpers_helper():
         pass # should not stop here except breakpoint
     """,
     """
     def helper_1():
         helpers_helper() # should not stop here
     """,
     """
     def helper_2():
         pass # should not stop here
     """,
     """
     def pdb_skipped_decorator2(function):
         def wrapped_fn(*args, **kwargs):
             __debuggerskip__ = True
             helper_2()
             __debuggerskip__ = False
             result = function(*args, **kwargs)
             __debuggerskip__ = True
             helper_2()
             return result
         return wrapped_fn
     """,
     """
     def pdb_skipped_decorator(function):
         def wrapped_fn(*args, **kwargs):
             __debuggerskip__ = True
             helper_1()
             __debuggerskip__ = False
             result = function(*args, **kwargs)
             __debuggerskip__ = True
             helper_2()
             return result
         return wrapped_fn
     """,
     """
     @pdb_skipped_decorator
     @pdb_skipped_decorator2
     def bar(x, y):
         return x * y
     """,
     """import IPython.terminal.debugger as ipdb""",
     """
     def f():
         ipdb.set_trace()
         bar(3, 4)
     """,
     """
     f()
     """,
 )
 
 
 def _decorator_skip_setup():
     import pexpect
 
     env = os.environ.copy()
     env["IPY_TEST_SIMPLE_PROMPT"] = "1"
 
     child = pexpect.spawn(
         sys.executable, ["-m", "IPython", "--colors=nocolor"], env=env
     )
     child.timeout = 5 * IPYTHON_TESTING_TIMEOUT_SCALE
 
     child.expect("IPython")
     child.expect("\n")
 
     dedented_blocks = [dedent(b).strip() for b in skip_decorators_blocks]
     in_prompt_number = 1
     for cblock in dedented_blocks:
         child.expect_exact(f"In [{in_prompt_number}]:")
         in_prompt_number += 1
         for line in cblock.splitlines():
             child.sendline(line)
             child.expect_exact(line)
         child.sendline("")
     return child
 
 
 @skip_win32
 def test_decorator_skip():
     """test that decorator frames can be skipped."""
 
     child = _decorator_skip_setup()
 
     child.expect_exact("3     bar(3, 4)")
     child.expect("ipdb>")
 
     child.expect("ipdb>")
     child.sendline("step")
     child.expect_exact("step")
 
     child.expect_exact("1 @pdb_skipped_decorator")
 
     child.sendline("s")
     child.expect_exact("return x * y")
 
     child.close()
 
 
 @skip_win32
 def test_decorator_skip_disabled():
     """test that decorator frame skipping can be disabled"""
 
     child = _decorator_skip_setup()
 
     child.expect_exact("3     bar(3, 4)")
 
     for input_, expected in [
         ("skip_predicates debuggerskip False", ""),
         ("skip_predicates", "debuggerskip : False"),
         ("step", "---> 2     def wrapped_fn"),
         ("step", "----> 3         __debuggerskip__"),
         ("step", "----> 4         helper_1()"),
         ("step", "---> 1 def helper_1():"),
         ("next", "----> 2     helpers_helper()"),
         ("next", "--Return--"),
         ("next", "----> 5         __debuggerskip__ = False"),
     ]:
         child.expect("ipdb>")
         child.sendline(input_)
         child.expect_exact(input_)
         child.expect_exact(expected)
 
     child.close()
 
 
 @skip_win32
 def test_decorator_skip_with_breakpoint():
     """test that decorator frame skipping can be disabled"""
 
     import pexpect
 
     env = os.environ.copy()
     env["IPY_TEST_SIMPLE_PROMPT"] = "1"
 
     child = pexpect.spawn(
         sys.executable, ["-m", "IPython", "--colors=nocolor"], env=env
     )
     child.timeout = 5 * IPYTHON_TESTING_TIMEOUT_SCALE
 
     child.expect("IPython")
     child.expect("\n")
 
     ### we need a filename, so we need to exec the full block with a filename
     with NamedTemporaryFile(suffix=".py", dir=".", delete=True) as tf:
 
         name = tf.name[:-3].split("/")[-1]
         tf.write("\n".join([dedent(x) for x in skip_decorators_blocks[:-1]]).encode())
         tf.flush()
         codeblock = f"from {name} import f"
 
         dedented_blocks = [
             codeblock,
             "f()",
         ]
 
         in_prompt_number = 1
         for cblock in dedented_blocks:
             child.expect_exact(f"In [{in_prompt_number}]:")
             in_prompt_number += 1
             for line in cblock.splitlines():
                 child.sendline(line)
                 child.expect_exact(line)
             child.sendline("")
 
         # as the filename does not exists, we'll rely on the filename prompt
         child.expect_exact("47     bar(3, 4)")
 
         for input_, expected in [
             (f"b {name}.py:3", ""),
             ("step", "1---> 3     pass # should not stop here except"),
             ("step", "---> 38 @pdb_skipped_decorator"),
             ("continue", ""),
         ]:
             child.expect("ipdb>")
             child.sendline(input_)
             child.expect_exact(input_)
             child.expect_exact(expected)
 
     child.close()
 
 
 @skip_win32
 def test_where_erase_value():
     """Test that `where` does not access f_locals and erase values."""
     import pexpect
 
     env = os.environ.copy()
     env["IPY_TEST_SIMPLE_PROMPT"] = "1"
 
     child = pexpect.spawn(
         sys.executable, ["-m", "IPython", "--colors=nocolor"], env=env
     )
     child.timeout = 15 * IPYTHON_TESTING_TIMEOUT_SCALE
 
     child.expect("IPython")
     child.expect("\n")
     child.expect_exact("In [1]")
 
     block = dedent(
         """
     def simple_f():
          myvar = 1
          print(myvar)
          1/0
          print(myvar)
     simple_f()    """
     )
 
     for line in block.splitlines():
         child.sendline(line)
         child.expect_exact(line)
     child.expect_exact("ZeroDivisionError")
     child.expect_exact("In [2]:")
 
     child.sendline("%debug")
 
     ##
     child.expect("ipdb>")
 
     child.sendline("myvar")
     child.expect("1")
 
     ##
     child.expect("ipdb>")
 
     child.sendline("myvar = 2")
 
     ##
     child.expect_exact("ipdb>")
 
     child.sendline("myvar")
 
     child.expect_exact("2")
 
     ##
     child.expect("ipdb>")
     child.sendline("where")
 
     ##
     child.expect("ipdb>")
     child.sendline("myvar")
 
     child.expect_exact("2")
     child.expect("ipdb>")
 
     child.close()