upstream/ipython Files · IPython/lib/tests/test_pygments.py

Swallow potential exceptions from showtraceback()...

Swallow potential exceptions from showtraceback() The nbgrader project is aware of a form of cheating where students disrupt `InteractiveShell.showtraceback` in hopes of hiding exceptions to avoid losing points. They have implemented a solution to prevent this cheating from working on the client side, and have some tests to demonstrate this technique: https://github.com/jupyter/nbgrader/blob/main/nbgrader/tests/apps/files/submitted-cheat-attempt.ipynb https://github.com/jupyter/nbgrader/blob/main/nbgrader/tests/apps/files/submitted-cheat-attempt-alternative.ipynb In essence, these attacks import the interactive shell and erase the traceback handler so that their failing tests won't report failures. import IPython.core.interactiveshell IPython.core.interactiveshell.InteractiveShell.showtraceback = None The problem is that this causes an exception inside the kernel, leading to a stalled execution. The kernel has stopped working, but the client continues to wait for messages. So far, nbgrader's solution to this is to require a timeout value so the client can eventually decide it is done. This prevents allowing a value of `None` for `Execute.timeout` because this would cause a test case to infinitely hang. This commit addresses the problem by making `InteractiveShell._run_cell` a little more protective around it's call to `showtraceback()`. There is already a try/except block around running the cell. This commit adds a finally clause so that the method will _always_ return an `ExecutionResult`, even if a new exception is thrown within the except clause. For the record, the exception thrown is: TypeError: 'NoneType' object is not callable Accepting this change will allow nbgrader to update `nbgrader.preprocessors.Execute` to support a type of `Integer(allow_none=True)` as the parent `NotebookClient` intended. Discussion about this is ongoing in jupyter/nbgrader#1690.

Nicholas Bollweg - - Load All Authors

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      from typing import List

      import pytest

      import pygments.lexers

      import pygments.lexer

      from IPython.lib.lexers import IPythonConsoleLexer, IPythonLexer, IPython3Lexer

      #: the human-readable names of the IPython lexers with ``entry_points``

      EXPECTED_LEXER_NAMES = [

          cls.name for cls in [IPythonConsoleLexer, IPythonLexer, IPython3Lexer]

      ]

      @pytest.fixture

      def all_pygments_lexer_names() -> List[str]:

          """Get all lexer names registered in pygments."""

          return {l[0] for l in pygments.lexers.get_all_lexers()}

      @pytest.mark.parametrize("expected_lexer", EXPECTED_LEXER_NAMES)

      def test_pygments_entry_points(

          expected_lexer: str, all_pygments_lexer_names: List[str]

      ) -> None:

          """Check whether the ``entry_points`` for ``pygments.lexers`` are correct."""

          assert expected_lexer in all_pygments_lexer_names

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				from typing import List

				import pytest
				import pygments.lexers
				import pygments.lexer

				from IPython.lib.lexers import IPythonConsoleLexer, IPythonLexer, IPython3Lexer

				#: the human-readable names of the IPython lexers with ``entry_points``
				EXPECTED_LEXER_NAMES = [
				cls.name for cls in [IPythonConsoleLexer, IPythonLexer, IPython3Lexer]
				]


				@pytest.fixture
				def all_pygments_lexer_names() -> List[str]:
				"""Get all lexer names registered in pygments."""
				return {l[0] for l in pygments.lexers.get_all_lexers()}


				@pytest.mark.parametrize("expected_lexer", EXPECTED_LEXER_NAMES)
				def test_pygments_entry_points(
				expected_lexer: str, all_pygments_lexer_names: List[str]
				) -> None:
				"""Check whether the ``entry_points`` for ``pygments.lexers`` are correct."""
				assert expected_lexer in all_pygments_lexer_names