Adds the 'contains' rule

Closes pyeve#358

CHANGES.rst

@@ -6,8 +6,10 @@ Here you can see the full list of changes between each Cerberus release.
 In Development
 --------------
 
-- Update README link. Make it point to the new PYPI website (Frank
- Sachsenheim).
+- New: The ``contains`` rule. (Frank Sachsenheim)
+
+- Update README link. Make it point to the new PyPI website. (Frank
+ Sachsenheim)
 
 Version 1.2
 -----------
@@ -23,8 +25,8 @@ Released on April 12, 2018.
  (Frank Sachsenheim)
 - New: Add errors.MAPPING_SCHEMA on errors within subdocuments.
  (Frank Sachsenheim)
-- New: Support for Types Definitions, which allow quick types check on the fly
- (Frank Sachsenheim).
+- New: Support for Types Definitions, which allow quick types check on the fly.
+ (Frank Sachsenheim)
 
 - Fix: Simplify the tests with Docker by using a volume for tox environments.
  (Frank Sachsenheim)
@@ -43,7 +45,7 @@ Released on April 12, 2018.
  Closes :issue:`269`. (Frank Sachsenheim)
 - Fix: A dependency is not considered satisfied if it has a null value.
  Closes :issue:`305`. (Frank Sachsenheim)
-- Override ``UnvalidatedSchema.copy`` (Peter Demin).
+- Override ``UnvalidatedSchema.copy``. (Peter Demin)
 - Fix: README link. (Gabriel Wainer)
 - Fix: Regression: allow_unknown causes dictionary validation to fail with
  a KeyError. Closes :issue:`302`. (Frank Sachsenheim)

cerberus/errors.py

@@ -54,6 +54,7 @@
 UNALLOWED_VALUES = ErrorDefinition(0x45, 'allowed')
 FORBIDDEN_VALUE = ErrorDefinition(0x46, 'forbidden')
 FORBIDDEN_VALUES = ErrorDefinition(0x47, 'forbidden')
+MISSING_MEMBERS = ErrorDefinition(0x48, 'contains')
 
 # other
 NORMALIZATION = ErrorDefinition(0x60, None)
@@ -461,6 +462,7 @@ class BasicErrorHandler(BaseErrorHandler):
  0x45: "unallowed values {0}",
  0x46: "unallowed value {value}",
  0x47: "unallowed values {0}",
+ 0x48: "missing members {0}",
 
  0x61: "field '{field}' cannot be coerced: {0}",
  0x62: "field '{field}' cannot be renamed: {0}",

cerberus/tests/test_validation.py

@@ -1577,3 +1577,21 @@ def test_allow_unknown_with_oneof_rules(validator):
  # check that allow_unknown is actually applied
  document = {'test': {'known': 's', 'unknown': 'asd'}}
  assert_success(document, validator=validator)
+
+
+@mark.parametrize('constraint',
+ (('Graham Chapman', 'Eric Idle'), 'Terry Gilliam'))
+def test_contains(constraint):
+ validator = Validator({'actors': {'contains': constraint}})
+
+ document = {'actors': ('Graham Chapman', 'Eric Idle', 'Terry Gilliam')}
+ assert validator(document)
+
+ document = {
+ 'actors': ('Eric idle', 'Terry Jones', 'John Cleese', 'Michael Palin')
+ }
+ assert not validator(document)
+ assert errors.MISSING_MEMBERS in validator.document_error_tree['actors']
+ missing_actors = \
+ validator.document_error_tree['actors'][errors.MISSING_MEMBERS].info[0]
+ assert any(x in missing_actors for x in ('Eric Idle', 'Terry Gilliam'))

cerberus/validator.py

@@ -964,6 +964,22 @@ def _validate_allowed(self, allowed_values, field, value):
  if value not in allowed_values:
  self._error(field, errors.UNALLOWED_VALUE, value)
 
+ def _validate_contains(self, expected_values, field, value):
+ # just to omit warnings about missing validation schema:
+ """ {'empty': True } """
+ if not isinstance(value, Iterable):
+ return
+
+ if (not isinstance(expected_values, Iterable) or
+ isinstance(expected_values, _str_type)):
+ expected_values = set((expected_values,))
+ else:
+ expected_values = set(expected_values)
+
+ missing_values = expected_values - set(value)
+ if missing_values:
+ self._error(field, errors.MISSING_MEMBERS, missing_values)
+
  def _validate_dependencies(self, dependencies, field, value):
  """ {'type': ('dict', 'hashable', 'list'),
  'validator': 'dependencies'} """

docs/validation-rules.rst

@@ -61,6 +61,31 @@ Validates if *any* of the provided constraints validates the field. See `\*of-ru
 
 .. versionadded:: 0.9
 
+contains
+--------
+This rule validates the a container object contains all of the defined items.
+
+.. doctest::
+
+ >>> document = {'states': ['peace', 'love', 'unity']}
+
+ >>> schema = {'states': {'contains': 'peace'}}
+ >>> v.validate(document, schema)
+ True
+
+ >>> schema = {'states': {'contains': 'greed'}}
+ >>> v.validate(document, schema)
+ False
+
+ >>> schema = {'states': {'contains': ['love', 'unity']}}
+ >>> v.validate(document, schema)
+ True
+
+ >>> schema = {'states': {'contains': ['love', 'laugh']}}
+ >>> v.validate(document, schema)
+ False
+
+
 .. _dependencies:
 
 dependencies