tests/scripts/generate_bignum_tests.py

#!/usr/bin/env python3
"""Generate test data for bignum functions.

With no arguments, generate all test data. With non-option arguments,
generate only the specified files.

Class structure:

Target classes are directly derived from test_generation.BaseTarget,
representing a target file. These indicate where test cases will be written
to in classes derived from the Target. Multiple Target classes must not
represent the same target_basename.

Each subclass derived from a Target can either be:
  - A concrete class, representing a test function, which generates test cases.
  - An abstract class containing shared methods and attributes, not associated
    with a test function. An example is BignumOperation, which provides common
    features used in binary bignum operations.


Adding test generation for a function:

A subclass representing the test function should be added, deriving from a
Target class or a descendant. This subclass must set/implement the following:
  - test_function: the function name from the associated .function file.
  - arguments(): generation of the arguments required for the test_function.
  - generate_function_test(): generation of the test cases for the function.

Additional details and other attributes/methods are given in the documentation
of BaseTarget in test_generation.py.
"""

# Copyright The Mbed TLS Contributors
# SPDX-License-Identifier: Apache-2.0
#
# 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
#
# http://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.

import itertools
import sys

from abc import abstractmethod
from typing import Callable, Dict, Iterator, List, Optional, Tuple, TypeVar

import scripts_path # pylint: disable=unused-import
from mbedtls_dev import test_case
from mbedtls_dev import test_generation

T = TypeVar('T') #pylint: disable=invalid-name

def hex_to_int(val):
    return int(val, 16) if val else 0

def quote_str(val):
    return "\"{}\"".format(val)


class BignumTarget(test_generation.BaseTarget):
    """Target for bignum (mpi) test case generation."""
    target_basename = 'test_suite_mpi.generated'


class BignumOperation(BignumTarget):
    """Common features for test cases covering binary bignum operations.

    This adds functionality common in binary operation tests. This includes
    generation of case descriptions, using descriptions of values and symbols
    to represent the operation or result.

    Attributes:
        symbol: Symbol used for the operation in case description.
        input_values: List of values to use as test case inputs. These are
            combined to produce pairs of values.
        input_cases: List of tuples containing pairs of test case inputs. This
            can be used to implement specific pairs of inputs.
    """
    symbol = ""
    input_values = [
        "", "0", "7b", "-7b",
        "0000000000000000123", "-0000000000000000123",
        "1230000000000000000", "-1230000000000000000"
    ] # type: List[str]
    input_cases = [] # type: List[Tuple[str, ...]]

    def __init__(self, val_l: str, val_r: str) -> None:
        super().__init__()

        self.arg_l = val_l
        self.arg_r = val_r
        self.int_l = hex_to_int(val_l)
        self.int_r = hex_to_int(val_r)

    def arguments(self):
        return [quote_str(self.arg_l), quote_str(self.arg_r), self.result()]

    def description(self):
        """Generate a description for the test case.

        If not set, case_description uses the form A `symbol` B, where symbol
        is used to represent the operation. Descriptions of each value are
        generated to provide some context to the test case.
        """
        if not self.case_description:
            self.case_description = "{} {} {}".format(
                self.value_description(self.arg_l),
                self.symbol,
                self.value_description(self.arg_r)
            )
        return super().description()

    @abstractmethod
    def result(self) -> Optional[str]:
        """Get the result of the operation.

        This may be calculated during initialization and stored as `_result`,
        or calculated when the method is called.
        """
        pass

    @staticmethod
    def value_description(val) -> str:
        """Generate a description of the argument val.

        This produces a simple description of the value, which are used in test
        case naming, to avoid most generated cases only being numbered.
        """
        if val == "":
            return "0 (null)"
        if val == "0":
            return "0 (1 limb)"

        if val[0] == "-":
            tmp = "negative"
            val = val[1:]
        else:
            tmp = "positive"
        if val[0] == "0":
            tmp += " with leading zero limb"
        elif len(val) > 10:
            tmp = "large " + tmp
        return tmp

    @classmethod
    def get_value_pairs(cls) -> Iterator[Tuple[str, ...]]:
        """Generator for pairs of inputs.

        Combinations are first generated from all input values, and then
        specific cases provided.
        """
        yield from itertools.combinations(cls.input_values, 2)
        yield from cls.input_cases

    @classmethod
    def generate_tests(cls) -> Iterator[test_case.TestCase]:
        if cls.test_function:
            # Generate tests for the current class
            for l_value, r_value in cls.get_value_pairs():
                cur_op = cls(l_value, r_value)
                yield cur_op.create_test_case()
        # Once current class completed, check descendants
        yield from super().generate_tests()


class BignumCmp(BignumOperation):
    """Target for bignum comparison test cases."""
    count = 0
    test_function = "mbedtls_mpi_cmp_mpi"
    test_name = "MPI compare"
    input_cases = [
        ("-2", "-3"),
        ("-2", "-2"),
        ("2b4", "2b5"),
        ("2b5", "2b6")
        ]

    def __init__(self, val_l, val_r):
        super().__init__(val_l, val_r)
        self._result = int(self.int_l > self.int_r) - int(self.int_l < self.int_r)
        self.symbol = ["<", "==", ">"][self._result + 1]

    def result(self):
        return str(self._result)


class BignumCmpAbs(BignumCmp):
    """Target for bignum comparison, absolute variant."""
    count = 0
    test_function = "mbedtls_mpi_cmp_abs"
    test_name = "MPI compare (abs)"

    def __init__(self, val_l, val_r):
        super().__init__(val_l.strip("-"), val_r.strip("-"))


class BignumAdd(BignumOperation):
    """Target for bignum addition test cases."""
    count = 0
    test_function = "mbedtls_mpi_add_mpi"
    test_name = "MPI add"
    input_cases = list(itertools.combinations(
        [
            "1c67967269c6", "9cde3",
            "-1c67967269c6", "-9cde3",
        ], 2
    ))

    def __init__(self, val_l, val_r):
        super().__init__(val_l, val_r)
        self.symbol = "+"

    def result(self):
        return quote_str(hex(self.int_l + self.int_r).replace("0x", "", 1))


class BignumTestGenerator(test_generation.TestGenerator):
    """Test generator subclass including bignum targets."""
    TARGETS = {
        subclass.target_basename: subclass.generate_tests for subclass in
        test_generation.BaseTarget.__subclasses__()
    } # type: Dict[str, Callable[[], test_case.TestCase]]

if __name__ == '__main__':
    test_generation.main(sys.argv[1:], BignumTestGenerator)