equivalent_repr_eval.py

# Copyright 2018 The Cirq Developers
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from typing import Any, Dict, Optional


def assert_equivalent_repr(
    value: Any,
    *,
    setup_code: str = (
        'import cirq\nimport numpy as np\nimport sympy\nimport pandas as pd\nimport datetime\n'
    ),
    global_vals: Optional[Dict[str, Any]] = None,
    local_vals: Optional[Dict[str, Any]] = None,
) -> None:
    """Checks that eval(repr(v)) == v.

    Args:
        value: A value whose repr should be evaluatable python
            code that produces an equivalent value.
        setup_code: Code that must be executed before the repr can be evaluated.
            Ideally this should just be a series of 'import' lines.
        global_vals: Pre-defined values that should be in the global scope when
            evaluating the repr.
        local_vals: Pre-defined values that should be in the local scope when
            evaluating the repr.

    Raises:
        AssertionError: If the assertion fails, or eval(repr(value)) raises an error.
    """
    __tracebackhide__ = True  # pylint: disable=unused-variable

    global_vals = global_vals or {}
    local_vals = local_vals or {}

    exec(setup_code, global_vals, local_vals)

    try:
        eval_repr_value = eval(repr(value), global_vals, local_vals)
    except Exception as ex:
        raise AssertionError(
            'eval(repr(value)) raised an exception.\n'
            '\n'
            f'setup_code={setup_code}\n'
            f'type(value): {type(value)}\n'
            f'value={value!r}\n'
            f'error={ex!r}'
        )

    assert eval_repr_value == value, (
        "The repr of a value of type {} didn't evaluate to something equal "
        "to the value.\n"
        'eval(repr(value)) != value\n'
        '\n'
        'value: {}\n'
        'repr(value): {!r}\n'
        'eval(repr(value)): {}\n'
        'repr(eval(repr(value))): {!r}\n'
        '\n'
        'type(value): {}\n'
        'type(eval(repr(value))): {!r}\n'
        '\n'
        'setup_code:\n{}\n'
    ).format(
        type(value),
        value,
        repr(value),
        eval_repr_value,
        repr(eval_repr_value),
        type(value),
        type(eval_repr_value),
        '    ' + setup_code.replace('\n', '\n    '),
    )

    try:
        a = eval(f'{value!r}.__class__', global_vals, local_vals)
    except Exception:
        raise AssertionError(
            f"The repr of a value of type {type(value)} wasn't 'dottable'.\n"
            f"{value!r}.XXX must be equivalent to ({value!r}).XXX, "
            "but it raised an error instead."
        )

    b = eval(f'({value!r}).__class__', global_vals, local_vals)
    assert a == b, (
        f"The repr of a value of type {type(value)} wasn't 'dottable'.\n"
        f"{value!r}.XXX must be equivalent to ({value!r}).XXX, "
        "but it wasn't."
    )