text: import unittest
  
  from django.core.checks import Error, Warning as DjangoWarning
  from django.db import connection, models
  from django.test import SimpleTestCase, TestCase, skipIfDBFeature
  from django.test.utils import isolate_apps, override_settings
  from django.utils.functional import lazy
  from django.utils.timezone import now
  from django.utils.translation import gettext_lazy as _
  
  
  @isolate_apps('invalid_models_tests')
  class AutoFieldTests(SimpleTestCase):
  
      def test_valid_case(self):
          class Model(models.Model):
              id = models.AutoField(primary_key=True)
  
          field = Model._meta.get_field('id')
          self.assertEqual(field.check(), [])
  
      def test_primary_key(self):
          # primary_key must be True. Refs #12467.
          class Model(models.Model):
              field = models.AutoField(primary_key=False)
  
              # Prevent Django from autocreating `id` AutoField, which would
              # result in an error, because a model must have exactly one
              # AutoField.
              another = models.IntegerField(primary_key=True)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  'AutoFields must set primary_key=True.',
                  obj=field,
                  id='fields.E100',
              ),
          ])
  
      def test_max_length_warning(self):
          class Model(models.Model):
              auto = models.AutoField(primary_key=True, max_length=2)
  
          field = Model._meta.get_field('auto')
          self.assertEqual(field.check(), [
              DjangoWarning(
                  "'max_length' is ignored when used with %s."
                  % field.__class__.__name__,
                  hint="Remove 'max_length' from field",
                  obj=field,
                  id='fields.W122',
              ),
          ])
  
  
  @isolate_apps('invalid_models_tests')
  class BinaryFieldTests(SimpleTestCase):
  
      def test_valid_default_value(self):
          class Model(models.Model):
              field1 = models.BinaryField(default=b'test')
              field2 = models.BinaryField(default=None)
  
          for field_name in ('field1', 'field2'):
              field = Model._meta.get_field(field_name)
              self.assertEqual(field.check(), [])
  
      def test_str_default_value(self):
          class Model(models.Model):
              field = models.BinaryField(default='test')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "BinaryField's default cannot be a string. Use bytes content "
                  "instead.",
                  obj=field,
                  id='fields.E170',
              ),
          ])
  
  
  @isolate_apps('invalid_models_tests')
  class CharFieldTests(SimpleTestCase):
  
      def test_valid_field(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=255,
                  choices=[
                      ('1', 'item1'),
                      ('2', 'item2'),
                  ],
                  db_index=True,
              )
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [])
  
      def test_missing_max_length(self):
          class Model(models.Model):
              field = models.CharField()
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "CharFields must define a 'max_length' attribute.",
                  obj=field,
                  id='fields.E120',
              ),
          ])
  
      def test_negative_max_length(self):
          class Model(models.Model):
              field = models.CharField(max_length=-1)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'max_length' must be a positive integer.",
                  obj=field,
                  id='fields.E121',
              ),
          ])
  
      def test_bad_max_length_value(self):
          class Model(models.Model):
              field = models.CharField(max_length="bad")
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'max_length' must be a positive integer.",
                  obj=field,
                  id='fields.E121',
              ),
          ])
  
      def test_str_max_length_value(self):
          class Model(models.Model):
              field = models.CharField(max_length='20')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'max_length' must be a positive integer.",
                  obj=field,
                  id='fields.E121',
              ),
          ])
  
      def test_str_max_length_type(self):
          class Model(models.Model):
              field = models.CharField(max_length=True)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'max_length' must be a positive integer.",
                  obj=field,
                  id='fields.E121'
              ),
          ])
  
      def test_non_iterable_choices(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, choices='bad')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'choices' must be an iterable (e.g., a list or tuple).",
                  obj=field,
                  id='fields.E004',
              ),
          ])
  
      def test_non_iterable_choices_two_letters(self):
          """Two letters isn't a valid choice pair."""
          class Model(models.Model):
              field = models.CharField(max_length=10, choices=['ab'])
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'choices' must be an iterable containing (actual value, "
                  "human readable name) tuples.",
                  obj=field,
                  id='fields.E005',
              ),
          ])
  
      def test_iterable_of_iterable_choices(self):
          class ThingItem:
              def __init__(self, value, display):
                  self.value = value
                  self.display = display
  
              def __iter__(self):
                  return iter((self.value, self.display))
  
              def __len__(self):
                  return 2
  
          class Things:
              def __iter__(self):
                  return iter((ThingItem(1, 2), ThingItem(3, 4)))
  
          class ThingWithIterableChoices(models.Model):
              thing = models.CharField(max_length=100, blank=True, choices=Things())
  
          self.assertEqual(ThingWithIterableChoices._meta.get_field('thing').check(), [])
  
      def test_choices_containing_non_pairs(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, choices=[(1, 2, 3), (1, 2, 3)])
  
          class Model2(models.Model):
              field = models.IntegerField(choices=[0])
  
          for model in (Model, Model2):
              with self.subTest(model.__name__):
                  field = model._meta.get_field('field')
                  self.assertEqual(field.check(), [
                      Error(
                          "'choices' must be an iterable containing (actual "
                          "value, human readable name) tuples.",
                          obj=field,
                          id='fields.E005',
                      ),
                  ])
  
      def test_choices_containing_lazy(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, choices=[['1', _('1')], ['2', _('2')]])
  
          self.assertEqual(Model._meta.get_field('field').check(), [])
  
      def test_lazy_choices(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, choices=lazy(lambda: [[1, '1'], [2, '2']], tuple)())
  
          self.assertEqual(Model._meta.get_field('field').check(), [])
  
      def test_choices_named_group(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=10, choices=[
                      ['knights', [['L', 'Lancelot'], ['G', 'Galahad']]],
                      ['wizards', [['T', 'Tim the Enchanter']]],
                      ['R', 'Random character'],
                  ],
              )
  
          self.assertEqual(Model._meta.get_field('field').check(), [])
  
      def test_choices_named_group_non_pairs(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=10,
                  choices=[['knights', [['L', 'Lancelot', 'Du Lac']]]],
              )
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'choices' must be an iterable containing (actual value, "
                  "human readable name) tuples.",
                  obj=field,
                  id='fields.E005',
              ),
          ])
  
      def test_choices_named_group_bad_structure(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=10, choices=[
                      ['knights', [
                          ['Noble', [['G', 'Galahad']]],
                          ['Combative', [['L', 'Lancelot']]],
                      ]],
                  ],
              )
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'choices' must be an iterable containing (actual value, "
                  "human readable name) tuples.",
                  obj=field,
                  id='fields.E005',
              ),
          ])
  
      def test_choices_named_group_lazy(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=10, choices=[
                      [_('knights'), [['L', _('Lancelot')], ['G', _('Galahad')]]],
                      ['R', _('Random character')],
                  ],
              )
  
          self.assertEqual(Model._meta.get_field('field').check(), [])
  
      def test_choices_in_max_length(self):
          class Model(models.Model):
              field = models.CharField(
                  max_length=2, choices=[
                      ('ABC', 'Value Too Long!'), ('OK', 'Good')
                  ],
              )
              group = models.CharField(
                  max_length=2, choices=[
                      ('Nested', [('OK', 'Good'), ('Longer', 'Longer')]),
                      ('Grouped', [('Bad', 'Bad')]),
                  ],
              )
  
          for name, choice_max_length in (('field', 3), ('group', 6)):
              with self.subTest(name):
                  field = Model._meta.get_field(name)
                  self.assertEqual(field.check(), [
                      Error(
                          "'max_length' is too small to fit the longest value "
                          "in 'choices' (%d characters)." % choice_max_length,
                          obj=field,
                          id='fields.E009',
                      ),
                  ])
  
      def test_bad_db_index_value(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, db_index='bad')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'db_index' must be None, True or False.",
                  obj=field,
                  id='fields.E006',
              ),
          ])
  
      def test_bad_validators(self):
          class Model(models.Model):
              field = models.CharField(max_length=10, validators=[True])
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "All 'validators' must be callable.",
                  hint=(
                      "validators[0] (True) isn't a function or instance of a "
                      "validator class."
                  ),
                  obj=field,
                  id='fields.E008',
              ),
          ])
  
      @unittest.skipUnless(connection.vendor == 'mysql',
                           "Test valid only for MySQL")
      def test_too_long_char_field_under_mysql(self):
          from django.db.backends.mysql.validation import DatabaseValidation
  
          class Model(models.Model):
              field = models.CharField(unique=True, max_length=256)
  
          field = Model._meta.get_field('field')
          validator = DatabaseValidation(connection=connection)
          self.assertEqual(validator.check_field(field), [
              Error(
                  'MySQL does not allow unique CharFields to have a max_length > 255.',
                  obj=field,
                  id='mysql.E001',
              )
          ])
  
  
  @isolate_apps('invalid_models_tests')
  class DateFieldTests(SimpleTestCase):
      maxDiff = None
  
      def test_auto_now_and_auto_now_add_raise_error(self):
          class Model(models.Model):
              field0 = models.DateTimeField(auto_now=True, auto_now_add=True, default=now)
              field1 = models.DateTimeField(auto_now=True, auto_now_add=False, default=now)
              field2 = models.DateTimeField(auto_now=False, auto_now_add=True, default=now)
              field3 = models.DateTimeField(auto_now=True, auto_now_add=True, default=None)
  
          expected = []
          checks = []
          for i in range(4):
              field = Model._meta.get_field('field%d' % i)
              expected.append(Error(
                  "The options auto_now, auto_now_add, and default "
                  "are mutually exclusive. Only one of these options "
                  "may be present.",
                  obj=field,
                  id='fields.E160',
              ))
              checks.extend(field.check())
              self.assertEqual(checks, expected)
  
      def test_fix_default_value(self):
          class Model(models.Model):
              field_dt = models.DateField(default=now())
              field_d = models.DateField(default=now().date())
              field_now = models.DateField(default=now)
  
          field_dt = Model._meta.get_field('field_dt')
          field_d = Model._meta.get_field('field_d')
          field_now = Model._meta.get_field('field_now')
          errors = field_dt.check()
          errors.extend(field_d.check())
          errors.extend(field_now.check())  # doesn't raise a warning
          self.assertEqual(errors, [
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_dt,
                  id='fields.W161',
              ),
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_d,
                  id='fields.W161',
              )
          ])
  
      @override_settings(USE_TZ=True)
      def test_fix_default_value_tz(self):
          self.test_fix_default_value()
  
  
  @isolate_apps('invalid_models_tests')
  class DateTimeFieldTests(SimpleTestCase):
      maxDiff = None
  
      def test_fix_default_value(self):
          class Model(models.Model):
              field_dt = models.DateTimeField(default=now())
              field_d = models.DateTimeField(default=now().date())
              field_now = models.DateTimeField(default=now)
  
          field_dt = Model._meta.get_field('field_dt')
          field_d = Model._meta.get_field('field_d')
          field_now = Model._meta.get_field('field_now')
          errors = field_dt.check()
          errors.extend(field_d.check())
          errors.extend(field_now.check())  # doesn't raise a warning
          self.assertEqual(errors, [
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_dt,
                  id='fields.W161',
              ),
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_d,
                  id='fields.W161',
              )
          ])
  
      @override_settings(USE_TZ=True)
      def test_fix_default_value_tz(self):
          self.test_fix_default_value()
  
  
  @isolate_apps('invalid_models_tests')
  class DecimalFieldTests(SimpleTestCase):
  
      def test_required_attributes(self):
          class Model(models.Model):
              field = models.DecimalField()
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "DecimalFields must define a 'decimal_places' attribute.",
                  obj=field,
                  id='fields.E130',
              ),
              Error(
                  "DecimalFields must define a 'max_digits' attribute.",
                  obj=field,
                  id='fields.E132',
              ),
          ])
  
      def test_negative_max_digits_and_decimal_places(self):
          class Model(models.Model):
              field = models.DecimalField(max_digits=-1, decimal_places=-1)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'decimal_places' must be a non-negative integer.",
                  obj=field,
                  id='fields.E131',
              ),
              Error(
                  "'max_digits' must be a positive integer.",
                  obj=field,
                  id='fields.E133',
              ),
          ])
  
      def test_bad_values_of_max_digits_and_decimal_places(self):
          class Model(models.Model):
              field = models.DecimalField(max_digits="bad", decimal_places="bad")
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'decimal_places' must be a non-negative integer.",
                  obj=field,
                  id='fields.E131',
              ),
              Error(
                  "'max_digits' must be a positive integer.",
                  obj=field,
                  id='fields.E133',
              ),
          ])
  
      def test_decimal_places_greater_than_max_digits(self):
          class Model(models.Model):
              field = models.DecimalField(max_digits=9, decimal_places=10)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'max_digits' must be greater or equal to 'decimal_places'.",
                  obj=field,
                  id='fields.E134',
              ),
          ])
  
      def test_valid_field(self):
          class Model(models.Model):
              field = models.DecimalField(max_digits=10, decimal_places=10)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [])
  
  
  @isolate_apps('invalid_models_tests')
  class FileFieldTests(SimpleTestCase):
  
      def test_valid_default_case(self):
          class Model(models.Model):
              field = models.FileField()
  
          self.assertEqual(Model._meta.get_field('field').check(), [])
  
      def test_valid_case(self):
          class Model(models.Model):
              field = models.FileField(upload_to='somewhere')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [])
  
      def test_primary_key(self):
          class Model(models.Model):
              field = models.FileField(primary_key=False, upload_to='somewhere')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "'primary_key' is not a valid argument for a FileField.",
                  obj=field,
                  id='fields.E201',
              )
          ])
  
      def test_upload_to_starts_with_slash(self):
          class Model(models.Model):
              field = models.FileField(upload_to='/somewhere')
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "FileField's 'upload_to' argument must be a relative path, not "
                  "an absolute path.",
                  obj=field,
                  id='fields.E202',
                  hint='Remove the leading slash.',
              )
          ])
  
      def test_upload_to_callable_not_checked(self):
          def callable(instance, filename):
              return '/' + filename
  
          class Model(models.Model):
              field = models.FileField(upload_to=callable)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [])
  
  
  @isolate_apps('invalid_models_tests')
  class FilePathFieldTests(SimpleTestCase):
  
      def test_forbidden_files_and_folders(self):
          class Model(models.Model):
              field = models.FilePathField(allow_files=False, allow_folders=False)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  "FilePathFields must have either 'allow_files' or 'allow_folders' set to True.",
                  obj=field,
                  id='fields.E140',
              ),
          ])
  
  
  @isolate_apps('invalid_models_tests')
  class GenericIPAddressFieldTests(SimpleTestCase):
  
      def test_non_nullable_blank(self):
          class Model(models.Model):
              field = models.GenericIPAddressField(null=False, blank=True)
  
          field = Model._meta.get_field('field')
          self.assertEqual(field.check(), [
              Error(
                  ('GenericIPAddressFields cannot have blank=True if null=False, '
                   'as blank values are stored as nulls.'),
                  obj=field,
                  id='fields.E150',
              ),
          ])
  
  
  @isolate_apps('invalid_models_tests')
  class ImageFieldTests(SimpleTestCase):
  
      def test_pillow_installed(self):
          try:
              from PIL import Image  # NOQA
          except ImportError:
              pillow_installed = False
          else:
              pillow_installed = True
  
          class Model(models.Model):
              field = models.ImageField(upload_to='somewhere')
  
          field = Model._meta.get_field('field')
          errors = field.check()
          expected = [] if pillow_installed else [
              Error(
                  'Cannot use ImageField because Pillow is not installed.',
                  hint=('Get Pillow at https://pypi.org/project/Pillow/ '
                        'or run command "python -m pip install Pillow".'),
                  obj=field,
                  id='fields.E210',
              ),
          ]
          self.assertEqual(errors, expected)
  
  
  @isolate_apps('invalid_models_tests')
  class IntegerFieldTests(SimpleTestCase):
  
      def test_max_length_warning(self):
          class Model(models.Model):
              integer = models.IntegerField(max_length=2)
              biginteger = models.BigIntegerField(max_length=2)
              smallinteger = models.SmallIntegerField(max_length=2)
              positiveinteger = models.PositiveIntegerField(max_length=2)
              positivesmallinteger = models.PositiveSmallIntegerField(max_length=2)
  
          for field in Model._meta.get_fields():
              if field.auto_created:
                  continue
              with self.subTest(name=field.name):
                  self.assertEqual(field.check(), [
                      DjangoWarning(
                          "'max_length' is ignored when used with %s." % field.__class__.__name__,
                          hint="Remove 'max_length' from field",
                          obj=field,
                          id='fields.W122',
                      )
                  ])
  
  
  @isolate_apps('invalid_models_tests')
  class TimeFieldTests(SimpleTestCase):
      maxDiff = None
  
      def test_fix_default_value(self):
          class Model(models.Model):
              field_dt = models.TimeField(default=now())
              field_t = models.TimeField(default=now().time())
              field_now = models.DateField(default=now)
  
          field_dt = Model._meta.get_field('field_dt')
          field_t = Model._meta.get_field('field_t')
          field_now = Model._meta.get_field('field_now')
          errors = field_dt.check()
          errors.extend(field_t.check())
          errors.extend(field_now.check())  # doesn't raise a warning
          self.assertEqual(errors, [
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_dt,
                  id='fields.W161',
              ),
              DjangoWarning(
                  'Fixed default value provided.',
                  hint='It seems you set a fixed date / time / datetime '
                       'value as default for this field. This may not be '
                       'what you want. If you want to have the current date '
                       'as default, use `django.utils.timezone.now`',
                  obj=field_t,
                  id='fields.W161',
              )
          ])
  
      @override_settings(USE_TZ=True)
      def test_fix_default_value_tz(self):
          self.test_fix_default_value()
  
  
  @isolate_apps('invalid_models_tests')
  class TextFieldTests(TestCase):
  
      @skipIfDBFeature('supports_index_on_text_field')
      def test_max_length_warning(self):
          class Model(models.Model):
              value = models.TextField(db_index=True)
          field = Model._meta.get_field('value')
          field_type = field.db_type(connection)
          self.assertEqual(field.check(), [
              DjangoWarning(
                  '%s does not support a database index on %s columns.'
                  % (connection.display_name, field_type),
                  hint=(
                      "An index won't be created. Silence this warning if you "
                      "don't care about it."
                  ),
                  obj=field,
                  id='fields.W162',
              )
          ])
  