from unittest import TestCase

from django.core.exceptions import ValidationError

from django.core.validators import EMPTY_VALUES

class LocalFlavorTestCase(TestCase):

    def assertFieldOutput(self, fieldclass, valid, invalid, field_args=[],

        field_kwargs={}, empty_value=u''):

        """Asserts that a field behaves correctly with various inputs.

        Args:

            fieldclass: the class of the field to be tested.

            valid: a dictionary mapping valid inputs to their expected

                    cleaned values.

            invalid: a dictionary mapping invalid inputs to one or more

                    raised error messages.

            fieldargs: the args passed to instantiate the field

            fieldkwargs: the kwargs passed to instantiate the field

            emptyvalue: the expected clean output for inputs in EMPTY_VALUES

        """

        required = fieldclass(*field_args, **field_kwargs)

        optional = fieldclass(*field_args, **dict(field_kwargs, required=False))

        # test valid inputs

        for input, output in valid.items():

            self.assertEqual(required.clean(input), output)

            self.assertEqual(optional.clean(input), output)

        # test invalid inputs

        for input, errors in invalid.items():

            try:

                required.clean(input)

            except ValidationError, e:

                self.assertEqual(errors, e.messages)

            else:

                self.fail()

            try:

                optional.clean(input)

            except ValidationError, e:

                self.assertEqual(errors, e.messages)

            else:

                self.fail()

        # test required inputs

        error_required = [u'This field is required.']

        for val in EMPTY_VALUES:

            try:

                required.clean(val)

            except ValidationError, e:

                self.assertEqual(error_required, e.messages)

            else:

                self.fail()

            self.assertEqual(optional.clean(val), empty_value)