# Copyright 2017 The Android Open Source Project
#
# 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.

def GetPadLength(block_size, length):
  return (block_size - (length % block_size)) % block_size


def InjectParameterizedTest(cls, param_list, name_generator):
  """Injects parameterized tests into the provided class

  This method searches for all tests that start with the name "ParamTest",
  and injects a test method for each set of parameters in param_list. Names
  are generated via the use of the name_generator.

  Args:
    cls: the class for which to inject all parameterized tests
    param_list: a list of tuples, where each tuple is a combination of
        of parameters to test (i.e. representing a single test case)
    name_generator: A function that takes a combination of parameters and
        returns a string that identifies the test case.
  """
  param_test_names = [name for name in dir(cls) if name.startswith("ParamTest")]

  # Force param_list to an actual list; otherwise itertools.Product will hit
  # the end, resulting in only the first ParamTest* method actually being
  # parameterized
  param_list = list(param_list)

  # Parameterize each test method starting with "ParamTest"
  for test_name in param_test_names:
    func = getattr(cls, test_name)

    for params in param_list:
      # Give the test method a readable, debuggable name.
      param_string = name_generator(*params)
      new_name = "%s_%s" % (func.__name__.replace("ParamTest", "test"),
                            param_string)
      new_name = new_name.replace("(", "-").replace(")", "")  # remove parens

      # Inject the test method
      setattr(cls, new_name, _GetTestClosure(func, params))


def _GetTestClosure(func, params):
  """ Creates a no-argument test method for the given function and parameters.

  This is required to be separate from the InjectParameterizedTest method, due
  to some interesting scoping issues with internal function declarations. If
  left in InjectParameterizedTest, all the tests end up using the same
  instance of TestClosure

  Args:
    func: the function for which this test closure should run
    params: the parameters for the run of this test function
  """

  def TestClosure(self):
    func(self, *params)

  return TestClosure