Пример #1
0
        def wrapped_test(*arguments, **kwargs):
            # Tell pytest to omit the body of this function from tracebacks
            __tracebackhide__ = True

            test = wrapped_test.hypothesis.inner_test

            if getattr(test, "is_hypothesis_test", False):
                raise InvalidArgument((
                    "You have applied @given to the test %s more than once, which "
                    "wraps the test several times and is extremely slow. A "
                    "similar effect can be gained by combining the arguments "
                    "of the two calls to given. For example, instead of "
                    "@given(booleans()) @given(integers()), you could write "
                    "@given(booleans(), integers())") % (test.__name__, ))

            settings = wrapped_test._hypothesis_internal_use_settings

            random = get_random_for_wrapped_test(test, wrapped_test)

            # Use type information to convert "infer" arguments into appropriate
            # strategies.
            if infer in given_kwargs.values():
                hints = get_type_hints(test)
            for name in [
                    name for name, value in given_kwargs.items()
                    if value is infer
            ]:
                if name not in hints:
                    raise InvalidArgument(
                        "passed %s=infer for %s, but %s has no type annotation"
                        % (name, test.__name__, name))
                given_kwargs[name] = st.from_type(hints[name])

            processed_args = process_arguments_to_given(
                wrapped_test,
                arguments,
                kwargs,
                given_kwargs,
                argspec,
                test,
                settings,
            )
            arguments, kwargs, test_runner, search_strategy = processed_args

            runner = getattr(search_strategy, "runner", None)
            if isinstance(runner, TestCase) and test.__name__ in dir(TestCase):
                msg = ("You have applied @given to the method %s, which is "
                       "used by the unittest runner but is not itself a test."
                       "  This is not useful in any way." % test.__name__)
                fail_health_check(settings, msg, HealthCheck.not_a_test_method)
            if bad_django_TestCase(runner):  # pragma: no cover
                # Covered by the Django tests, but not the pytest coverage task
                raise InvalidArgument(
                    "You have applied @given to a method on %s, but this "
                    "class does not inherit from the supported versions in "
                    "`hypothesis.extra.django`.  Use the Hypothesis variants "
                    "to ensure that each example is run in a separate "
                    "database transaction." % qualname(type(runner)))

            state = StateForActualGivenExecution(
                test_runner,
                search_strategy,
                test,
                settings,
                random,
                wrapped_test,
            )

            reproduce_failure = wrapped_test._hypothesis_internal_use_reproduce_failure

            # If there was a @reproduce_failure decorator, use it to reproduce
            # the error (or complain that we couldn't). Either way, this will
            # always raise some kind of error.
            if reproduce_failure is not None:
                expected_version, failure = reproduce_failure
                if expected_version != __version__:
                    raise InvalidArgument(
                        ("Attempting to reproduce a failure from a different "
                         "version of Hypothesis. This failure is from %s, but "
                         "you are currently running %r. Please change your "
                         "Hypothesis version to a matching one.") %
                        (expected_version, __version__))
                try:
                    state.execute_once(
                        ConjectureData.for_buffer(decode_failure(failure)),
                        print_example=True,
                        is_final=True,
                    )
                    raise DidNotReproduce(
                        "Expected the test to raise an error, but it "
                        "completed successfully.")
                except StopTest:
                    raise DidNotReproduce(
                        "The shape of the test data has changed in some way "
                        "from where this blob was defined. Are you sure "
                        "you're running the same test?")
                except UnsatisfiedAssumption:
                    raise DidNotReproduce(
                        "The test data failed to satisfy an assumption in the "
                        "test. Have you added it since this blob was "
                        "generated?")

            # There was no @reproduce_failure, so start by running any explicit
            # examples from @example decorators.

            execute_explicit_examples(state, wrapped_test, arguments, kwargs)

            # If there were any explicit examples, they all ran successfully.
            # The next step is to use the Conjecture engine to run the test on
            # many different inputs.

            if settings.max_examples <= 0:
                return

            if not (Phase.reuse in settings.phases
                    or Phase.generate in settings.phases):
                return

            try:
                if isinstance(runner, TestCase) and hasattr(runner, "subTest"):
                    subTest = runner.subTest
                    try:
                        runner.subTest = fake_subTest
                        state.run_engine()
                    finally:
                        runner.subTest = subTest
                else:
                    state.run_engine()
            except BaseException as e:
                # The exception caught here should either be an actual test
                # failure (or MultipleFailures), or some kind of fatal error
                # that caused the engine to stop.

                generated_seed = wrapped_test._hypothesis_internal_use_generated_seed
                with local_settings(settings):
                    if not (state.failed_normally or generated_seed is None):
                        if running_under_pytest:
                            report(
                                "You can add @seed(%(seed)d) to this test or "
                                "run pytest with --hypothesis-seed=%(seed)d "
                                "to reproduce this failure." %
                                {"seed": generated_seed})
                        else:
                            report("You can add @seed(%d) to this test to "
                                   "reproduce this failure." %
                                   (generated_seed, ))
                    # The dance here is to avoid showing users long tracebacks
                    # full of Hypothesis internals they don't care about.
                    # We have to do this inline, to avoid adding another
                    # internal stack frame just when we've removed the rest.
                    if PY2:
                        # Python 2 doesn't have Exception.with_traceback(...);
                        # instead it has a three-argument form of the `raise`
                        # statement.  Unfortunately this is a SyntaxError on
                        # Python 3, and before Python 2.7.9 it was *also* a
                        # SyntaxError to use it in a nested function so we
                        # can't `exec` or `eval` our way out (BPO-21591).
                        # So unless we break some versions of Python 2, none
                        # of them get traceback elision.
                        raise
                    # On Python 3, we swap out the real traceback for our
                    # trimmed version.  Using a variable ensures that the line
                    # which will actually appear in tracebacks is as clear as
                    # possible - "raise the_error_hypothesis_found".
                    the_error_hypothesis_found = e.with_traceback(
                        get_trimmed_traceback())
                    raise the_error_hypothesis_found
Пример #2
0
        def wrapped_test(*arguments, **kwargs):
            # Tell pytest to omit the body of this function from tracebacks
            __tracebackhide__ = True

            test = wrapped_test.hypothesis.inner_test

            if getattr(test, 'is_hypothesis_test', False):
                note_deprecation((
                    'You have applied @given to test: %s more than once. In '
                    'future this will be an error. Applying @given twice '
                    'wraps the test twice, which can be extremely slow. A '
                    'similar effect can be gained by combining the arguments '
                    'of the two calls to given. For example, instead of '
                    '@given(booleans()) @given(integers()), you could write '
                    '@given(booleans(), integers())') % (test.__name__, )
                )

            settings = wrapped_test._hypothesis_internal_use_settings

            random = get_random_for_wrapped_test(test, wrapped_test)

            if infer in generator_kwargs.values():
                hints = get_type_hints(test)
            for name in [name for name, value in generator_kwargs.items()
                         if value is infer]:
                if name not in hints:
                    raise InvalidArgument(
                        'passed %s=infer for %s, but %s has no type annotation'
                        % (name, test.__name__, name))
                generator_kwargs[name] = st.from_type(hints[name])

            processed_args = process_arguments_to_given(
                wrapped_test, arguments, kwargs, generator_arguments,
                generator_kwargs, argspec, test, settings
            )
            arguments, kwargs, test_runner, search_strategy = processed_args

            runner = getattr(search_strategy, 'runner', None)
            if isinstance(runner, TestCase) and test.__name__ in dir(TestCase):
                msg = ('You have applied @given to the method %s, which is '
                       'used by the unittest runner but is not itself a test.'
                       '  This is not useful in any way.' % test.__name__)
                fail_health_check(settings, msg, HealthCheck.not_a_test_method)
            if bad_django_TestCase(runner):  # pragma: no cover
                # Covered by the Django tests, but not the pytest coverage task
                raise InvalidArgument(
                    'You have applied @given to a method on %s, but this '
                    'class does not inherit from the supported versions in '
                    '`hypothesis.extra.django`.  Use the Hypothesis variants '
                    'to ensure that each example is run in a separate '
                    'database transaction.' % qualname(type(runner))
                )

            state = StateForActualGivenExecution(
                test_runner, search_strategy, test, settings, random,
                had_seed=wrapped_test._hypothesis_internal_use_seed
            )

            reproduce_failure = \
                wrapped_test._hypothesis_internal_use_reproduce_failure

            if reproduce_failure is not None:
                expected_version, failure = reproduce_failure
                if expected_version != __version__:
                    raise InvalidArgument((
                        'Attempting to reproduce a failure from a different '
                        'version of Hypothesis. This failure is from %s, but '
                        'you are currently running %r. Please change your '
                        'Hypothesis version to a matching one.'
                    ) % (expected_version, __version__))
                try:
                    state.execute(ConjectureData.for_buffer(
                        decode_failure(failure)),
                        print_example=True, is_final=True,
                    )
                    raise DidNotReproduce(
                        'Expected the test to raise an error, but it '
                        'completed successfully.'
                    )
                except StopTest:
                    raise DidNotReproduce(
                        'The shape of the test data has changed in some way '
                        'from where this blob was defined. Are you sure '
                        "you're running the same test?"
                    )
                except UnsatisfiedAssumption:
                    raise DidNotReproduce(
                        'The test data failed to satisfy an assumption in the '
                        'test. Have you added it since this blob was '
                        'generated?'
                    )

            execute_explicit_examples(
                test_runner, test, wrapped_test, settings, arguments, kwargs
            )

            if settings.max_examples <= 0:
                return

            if not (
                Phase.reuse in settings.phases or
                Phase.generate in settings.phases
            ):
                return

            try:
                if isinstance(runner, TestCase) and hasattr(runner, 'subTest'):
                    subTest = runner.subTest
                    try:
                        setattr(runner, 'subTest', fake_subTest)
                        state.run()
                    finally:
                        setattr(runner, 'subTest', subTest)
                else:
                    state.run()
            except BaseException:
                generated_seed = \
                    wrapped_test._hypothesis_internal_use_generated_seed
                if generated_seed is not None and not state.failed_normally:
                    with local_settings(settings):
                        if running_under_pytest:
                            report(
                                'You can add @seed(%(seed)d) to this test or '
                                'run pytest with --hypothesis-seed=%(seed)d '
                                'to reproduce this failure.' % {
                                    'seed': generated_seed})
                        else:
                            report(
                                'You can add @seed(%d) to this test to '
                                'reproduce this failure.' % (generated_seed,))
                raise
Пример #3
0
        def wrapped_test(*arguments, **kwargs):
            # Tell pytest to omit the body of this function from tracebacks
            __tracebackhide__ = True

            test = wrapped_test.hypothesis.inner_test

            if getattr(test, 'is_hypothesis_test', False):
                note_deprecation(
                    ('You have applied @given to test: %s more than once. In '
                     'future this will be an error. Applying @given twice '
                     'wraps the test twice, which can be extremely slow. A '
                     'similar effect can be gained by combining the arguments '
                     'of the two calls to given. For example, instead of '
                     '@given(booleans()) @given(integers()), you could write '
                     '@given(booleans(), integers())') % (test.__name__, ))

            settings = wrapped_test._hypothesis_internal_use_settings

            random = get_random_for_wrapped_test(test, wrapped_test)

            if infer in generator_kwargs.values():
                hints = get_type_hints(test)
            for name in [
                    name for name, value in generator_kwargs.items()
                    if value is infer
            ]:
                if name not in hints:
                    raise InvalidArgument(
                        'passed %s=infer for %s, but %s has no type annotation'
                        % (name, test.__name__, name))
                generator_kwargs[name] = st.from_type(hints[name])

            processed_args = process_arguments_to_given(
                wrapped_test, arguments, kwargs, generator_arguments,
                generator_kwargs, argspec, test, settings)
            arguments, kwargs, test_runner, search_strategy = processed_args

            runner = getattr(search_strategy, 'runner', None)
            if isinstance(runner, TestCase) and test.__name__ in dir(TestCase):
                msg = ('You have applied @given to the method %s, which is '
                       'used by the unittest runner but is not itself a test.'
                       '  This is not useful in any way.' % test.__name__)
                fail_health_check(settings, msg, HealthCheck.not_a_test_method)
            if bad_django_TestCase(runner):  # pragma: no cover
                # Covered by the Django tests, but not the pytest coverage task
                raise InvalidArgument(
                    'You have applied @given to a method on %s, but this '
                    'class does not inherit from the supported versions in '
                    '`hypothesis.extra.django`.  Use the Hypothesis variants '
                    'to ensure that each example is run in a separate '
                    'database transaction.' % qualname(type(runner)))

            state = StateForActualGivenExecution(
                test_runner,
                search_strategy,
                test,
                settings,
                random,
                had_seed=wrapped_test._hypothesis_internal_use_seed)

            reproduce_failure = \
                wrapped_test._hypothesis_internal_use_reproduce_failure

            if reproduce_failure is not None:
                expected_version, failure = reproduce_failure
                if expected_version != __version__:
                    raise InvalidArgument(
                        ('Attempting to reproduce a failure from a different '
                         'version of Hypothesis. This failure is from %s, but '
                         'you are currently running %r. Please change your '
                         'Hypothesis version to a matching one.') %
                        (expected_version, __version__))
                try:
                    state.execute(
                        ConjectureData.for_buffer(decode_failure(failure)),
                        print_example=True,
                        is_final=True,
                    )
                    raise DidNotReproduce(
                        'Expected the test to raise an error, but it '
                        'completed successfully.')
                except StopTest:
                    raise DidNotReproduce(
                        'The shape of the test data has changed in some way '
                        'from where this blob was defined. Are you sure '
                        "you're running the same test?")
                except UnsatisfiedAssumption:
                    raise DidNotReproduce(
                        'The test data failed to satisfy an assumption in the '
                        'test. Have you added it since this blob was '
                        'generated?')

            execute_explicit_examples(test_runner, test, wrapped_test,
                                      settings, arguments, kwargs)

            if settings.max_examples <= 0:
                return

            if not (Phase.reuse in settings.phases
                    or Phase.generate in settings.phases):
                return

            try:
                if isinstance(runner, TestCase) and hasattr(runner, 'subTest'):
                    subTest = runner.subTest
                    try:
                        setattr(runner, 'subTest', fake_subTest)
                        state.run()
                    finally:
                        setattr(runner, 'subTest', subTest)
                else:
                    state.run()
            except BaseException as e:
                generated_seed = \
                    wrapped_test._hypothesis_internal_use_generated_seed
                with local_settings(settings):
                    if not (state.failed_normally or generated_seed is None):
                        if running_under_pytest:
                            report(
                                'You can add @seed(%(seed)d) to this test or '
                                'run pytest with --hypothesis-seed=%(seed)d '
                                'to reproduce this failure.' %
                                {'seed': generated_seed})
                        else:
                            report('You can add @seed(%d) to this test to '
                                   'reproduce this failure.' %
                                   (generated_seed, ))
                    # The dance here is to avoid showing users long tracebacks
                    # full of Hypothesis internals they don't care about.
                    # We have to do this inline, to avoid adding another
                    # internal stack frame just when we've removed the rest.
                    if PY2:
                        # Python 2 doesn't have Exception.with_traceback(...);
                        # instead it has a three-argument form of the `raise`
                        # statement.  Unfortunately this is a SyntaxError on
                        # Python 3, and before Python 2.7.9 it was *also* a
                        # SyntaxError to use it in a nested function so we
                        # can't `exec` or `eval` our way out (BPO-21591).
                        # So unless we break some versions of Python 2, none
                        # of them get traceback elision.
                        raise
                    # On Python 3, we swap out the real traceback for our
                    # trimmed version.  Using a variable ensures that the line
                    # which will actually appear in trackbacks is as clear as
                    # possible - "raise the_error_hypothesis_found".
                    the_error_hypothesis_found = \
                        e.with_traceback(get_trimmed_traceback())
                    raise the_error_hypothesis_found
Пример #4
0
        def wrapped_test(*arguments, **kwargs):
            # Tell pytest to omit the body of this function from tracebacks
            __tracebackhide__ = True

            if getattr(test, 'is_hypothesis_test', False):
                note_deprecation(
                    'You have applied @given to a test more than once. In '
                    'future this will be an error. Applying @given twice '
                    'wraps the test twice, which can be extremely slow. A '
                    'similar effect can be gained by combining the arguments '
                    'of the two calls to given. For example, instead of '
                    '@given(booleans()) @given(integers()), you could write '
                    '@given(booleans(), integers())')

            settings = wrapped_test._hypothesis_internal_use_settings

            random = get_random_for_wrapped_test(test, wrapped_test)

            if infer in generator_kwargs.values():
                hints = get_type_hints(test)
            for name in [
                    name for name, value in generator_kwargs.items()
                    if value is infer
            ]:
                if name not in hints:
                    raise InvalidArgument(
                        'passed %s=infer for %s, but %s has no type annotation'
                        % (name, test.__name__, name))
                generator_kwargs[name] = st.from_type(hints[name])

            processed_args = process_arguments_to_given(
                wrapped_test, arguments, kwargs, generator_arguments,
                generator_kwargs, argspec, test, settings)
            arguments, kwargs, test_runner, search_strategy = processed_args

            runner = getattr(search_strategy, 'runner', None)
            if isinstance(runner, TestCase) and test.__name__ in dir(TestCase):
                msg = ('You have applied @given to the method %s, which is '
                       'used by the unittest runner but is not itself a test.'
                       '  This is not useful in any way.' % test.__name__)
                fail_health_check(settings, msg, HealthCheck.not_a_test_method)
            if bad_django_TestCase(runner):  # pragma: no cover
                # Covered by the Django tests, but not the pytest coverage task
                raise InvalidArgument(
                    'You have applied @given to a method on %s, but this '
                    'class does not inherit from the supported versions in '
                    '`hypothesis.extra.django`.  Use the Hypothesis variants '
                    'to ensure that each example is run in a separate '
                    'database transaction.' % qualname(type(runner)))

            state = StateForActualGivenExecution(
                test_runner,
                search_strategy,
                test,
                settings,
                random,
                had_seed=wrapped_test._hypothesis_internal_use_seed)

            reproduce_failure = \
                wrapped_test._hypothesis_internal_use_reproduce_failure

            if reproduce_failure is not None:
                expected_version, failure = reproduce_failure
                if expected_version != __version__:
                    raise InvalidArgument(
                        ('Attempting to reproduce a failure from a different '
                         'version of Hypothesis. This failure is from %s, but '
                         'you are currently running %r. Please change your '
                         'Hypothesis version to a matching one.') %
                        (expected_version, __version__))
                try:
                    state.execute(
                        ConjectureData.for_buffer(decode_failure(failure)),
                        print_example=True,
                        is_final=True,
                    )
                    raise DidNotReproduce(
                        'Expected the test to raise an error, but it '
                        'completed successfully.')
                except StopTest:
                    raise DidNotReproduce(
                        'The shape of the test data has changed in some way '
                        'from where this blob was defined. Are you sure '
                        "you're running the same test?")
                except UnsatisfiedAssumption:
                    raise DidNotReproduce(
                        'The test data failed to satisfy an assumption in the '
                        'test. Have you added it since this blob was '
                        'generated?')

            execute_explicit_examples(test_runner, test, wrapped_test,
                                      settings, arguments, kwargs)

            if settings.max_examples <= 0:
                return

            if not (Phase.reuse in settings.phases
                    or Phase.generate in settings.phases):
                return

            try:
                if isinstance(runner, TestCase) and hasattr(runner, 'subTest'):
                    subTest = runner.subTest
                    try:
                        setattr(runner, 'subTest', fake_subTest)
                        state.run()
                    finally:
                        setattr(runner, 'subTest', subTest)
                else:
                    state.run()
            except BaseException:
                generated_seed = \
                    wrapped_test._hypothesis_internal_use_generated_seed
                if generated_seed is not None and not state.failed_normally:
                    if running_under_pytest:
                        report(
                            ('You can add @seed(%(seed)d) to this test or run '
                             'pytest with --hypothesis-seed=%(seed)d to '
                             'reproduce this failure.') %
                            {'seed': generated_seed}, )
                    else:
                        report(
                            ('You can add @seed(%d) to this test to reproduce '
                             'this failure.') % (generated_seed, ))
                raise
Пример #5
0
        def wrapped_test(*arguments, **kwargs):
            # Tell pytest to omit the body of this function from tracebacks
            __tracebackhide__ = True

            test = wrapped_test.hypothesis.inner_test

            if getattr(test, "is_hypothesis_test", False):
                raise InvalidArgument(
                    (
                        "You have applied @given to the test %s more than once, which "
                        "wraps the test several times and is extremely slow. A "
                        "similar effect can be gained by combining the arguments "
                        "of the two calls to given. For example, instead of "
                        "@given(booleans()) @given(integers()), you could write "
                        "@given(booleans(), integers())"
                    )
                    % (test.__name__,)
                )

            settings = wrapped_test._hypothesis_internal_use_settings

            random = get_random_for_wrapped_test(test, wrapped_test)

            if infer in generator_kwargs.values():
                hints = get_type_hints(test)
            for name in [
                name for name, value in generator_kwargs.items() if value is infer
            ]:
                if name not in hints:
                    raise InvalidArgument(
                        "passed %s=infer for %s, but %s has no type annotation"
                        % (name, test.__name__, name)
                    )
                generator_kwargs[name] = st.from_type(hints[name])

            processed_args = process_arguments_to_given(
                wrapped_test,
                arguments,
                kwargs,
                generator_arguments,
                generator_kwargs,
                argspec,
                test,
                settings,
            )
            arguments, kwargs, test_runner, search_strategy = processed_args

            runner = getattr(search_strategy, "runner", None)
            if isinstance(runner, TestCase) and test.__name__ in dir(TestCase):
                msg = (
                    "You have applied @given to the method %s, which is "
                    "used by the unittest runner but is not itself a test."
                    "  This is not useful in any way." % test.__name__
                )
                fail_health_check(settings, msg, HealthCheck.not_a_test_method)
            if bad_django_TestCase(runner):  # pragma: no cover
                # Covered by the Django tests, but not the pytest coverage task
                raise InvalidArgument(
                    "You have applied @given to a method on %s, but this "
                    "class does not inherit from the supported versions in "
                    "`hypothesis.extra.django`.  Use the Hypothesis variants "
                    "to ensure that each example is run in a separate "
                    "database transaction." % qualname(type(runner))
                )

            state = StateForActualGivenExecution(
                test_runner,
                search_strategy,
                test,
                settings,
                random,
                had_seed=wrapped_test._hypothesis_internal_use_seed,
            )

            reproduce_failure = wrapped_test._hypothesis_internal_use_reproduce_failure

            if reproduce_failure is not None:
                expected_version, failure = reproduce_failure
                if expected_version != __version__:
                    raise InvalidArgument(
                        (
                            "Attempting to reproduce a failure from a different "
                            "version of Hypothesis. This failure is from %s, but "
                            "you are currently running %r. Please change your "
                            "Hypothesis version to a matching one."
                        )
                        % (expected_version, __version__)
                    )
                try:
                    state.execute(
                        ConjectureData.for_buffer(decode_failure(failure)),
                        print_example=True,
                        is_final=True,
                    )
                    raise DidNotReproduce(
                        "Expected the test to raise an error, but it "
                        "completed successfully."
                    )
                except StopTest:
                    raise DidNotReproduce(
                        "The shape of the test data has changed in some way "
                        "from where this blob was defined. Are you sure "
                        "you're running the same test?"
                    )
                except UnsatisfiedAssumption:
                    raise DidNotReproduce(
                        "The test data failed to satisfy an assumption in the "
                        "test. Have you added it since this blob was "
                        "generated?"
                    )

            execute_explicit_examples(
                test_runner, test, wrapped_test, settings, arguments, kwargs
            )

            if settings.max_examples <= 0:
                return

            if not (
                Phase.reuse in settings.phases or Phase.generate in settings.phases
            ):
                return

            try:
                if isinstance(runner, TestCase) and hasattr(runner, "subTest"):
                    subTest = runner.subTest
                    try:
                        setattr(runner, "subTest", fake_subTest)
                        state.run()
                    finally:
                        setattr(runner, "subTest", subTest)
                else:
                    state.run()
            except BaseException as e:
                generated_seed = wrapped_test._hypothesis_internal_use_generated_seed
                with local_settings(settings):
                    if not (state.failed_normally or generated_seed is None):
                        if running_under_pytest:
                            report(
                                "You can add @seed(%(seed)d) to this test or "
                                "run pytest with --hypothesis-seed=%(seed)d "
                                "to reproduce this failure." % {"seed": generated_seed}
                            )
                        else:
                            report(
                                "You can add @seed(%d) to this test to "
                                "reproduce this failure." % (generated_seed,)
                            )
                    # The dance here is to avoid showing users long tracebacks
                    # full of Hypothesis internals they don't care about.
                    # We have to do this inline, to avoid adding another
                    # internal stack frame just when we've removed the rest.
                    if PY2:
                        # Python 2 doesn't have Exception.with_traceback(...);
                        # instead it has a three-argument form of the `raise`
                        # statement.  Unfortunately this is a SyntaxError on
                        # Python 3, and before Python 2.7.9 it was *also* a
                        # SyntaxError to use it in a nested function so we
                        # can't `exec` or `eval` our way out (BPO-21591).
                        # So unless we break some versions of Python 2, none
                        # of them get traceback elision.
                        raise
                    # On Python 3, we swap out the real traceback for our
                    # trimmed version.  Using a variable ensures that the line
                    # which will actually appear in trackbacks is as clear as
                    # possible - "raise the_error_hypothesis_found".
                    the_error_hypothesis_found = e.with_traceback(
                        get_trimmed_traceback()
                    )
                    raise the_error_hypothesis_found