Adding SomeOf validator (#314)

Adding SomeOf validator and corresponding tests.

voluptuous/error.py

@@ -187,3 +187,13 @@ class NotInInvalid(Invalid):
 
 class ExactSequenceInvalid(Invalid):
     pass
+
+
+class NotEnoughValid(Invalid):
+    """The value did not pass enough validations."""
+    pass
+
+
+class TooManyValid(Invalid):
+    """The value passed more than expected validations."""
+    pass

voluptuous/tests/tests.py

@@ -10,7 +10,7 @@
     Url, MultipleInvalid, LiteralInvalid, TypeInvalid, NotIn, Match, Email,
     Replace, Range, Coerce, All, Any, Length, FqdnUrl, ALLOW_EXTRA, PREVENT_EXTRA,
     validate, ExactSequence, Equal, Unordered, Number, Maybe, Datetime, Date,
-    Contains, Marker, IsDir, IsFile, PathExists)
+    Contains, Marker, IsDir, IsFile, PathExists, SomeOf, TooManyValid, raises)
 from voluptuous.humanize import humanize_error
 from voluptuous.util import u
 
@@ -1031,3 +1031,40 @@ def test_description():
 
     required = Required('key', description='Hello')
     assert required.description == 'Hello'
+
+
+def test_SomeOf_min_validation():
+    validator = All(Length(min=8), SomeOf(
+        min_valid=3,
+        validators=[Match(r'.*[A-Z]', 'no uppercase letters'),
+                    Match(r'.*[a-z]', 'no lowercase letters'),
+                    Match(r'.*[0-9]', 'no numbers'),
+                    Match(r'.*[$@$!%*#?&^:;/<,>|{}()\-\'._+=]', 'no symbols')]))
+
+    validator('ffe532A1!')
+    with raises(MultipleInvalid, 'length of value must be at least 8'):
+        validator('a')
+
+    with raises(MultipleInvalid, 'no uppercase letters, no lowercase letters'):
+        validator('wqs2!#s111')
+
+    with raises(MultipleInvalid, 'no lowercase letters, no symbols'):
+        validator('3A34SDEF5')
+
+
+def test_SomeOf_max_validation():
+    validator = SomeOf(
+        max_valid=2,
+        validators=[Match(r'.*[A-Z]', 'no uppercase letters'),
+                    Match(r'.*[a-z]', 'no lowercase letters'),
+                    Match(r'.*[0-9]', 'no numbers')],
+        msg='max validation test failed')
+
+    validator('Aa')
+    with raises(TooManyValid, 'max validation test failed'):
+        validator('Aa1')
+
+
+def test_SomeOf_on_bounds_assertion():
+    with raises(AssertionError, 'when using "SomeOf" you should specify at least one of min_valid and max_valid'):
+        SomeOf(validators=[])

voluptuous/validators.py

@@ -9,7 +9,8 @@
 from voluptuous.error import (MultipleInvalid, CoerceInvalid, TrueInvalid, FalseInvalid, BooleanInvalid, Invalid,
                               AnyInvalid, AllInvalid, MatchInvalid, UrlInvalid, EmailInvalid, FileInvalid, DirInvalid,
                               RangeInvalid, PathInvalid, ExactSequenceInvalid, LengthInvalid, DatetimeInvalid,
-                              DateInvalid, InInvalid, TypeInvalid, NotInInvalid, ContainsInvalid)
+                              DateInvalid, InInvalid, TypeInvalid, NotInInvalid, ContainsInvalid, NotEnoughValid,
+                              TooManyValid)
 
 if sys.version_info >= (3,):
     import urllib.parse as urlparse
@@ -933,3 +934,61 @@ def _get_precision_scale(self, number):
             raise Invalid(self.msg or 'Value must be a number enclosed with string')
 
         return (len(decimal_num.as_tuple().digits), -(decimal_num.as_tuple().exponent), decimal_num)
+
+
+class SomeOf(object):
+    """Value must pass at least some validations, determined by the given parameter.
+    Optionally, number of passed validations can be capped.
+
+    The output of each validator is passed as input to the next.
+
+    :param min_valid: Minimum number of valid schemas.
+    :param validators: a list of schemas or validators to match input against
+    :param max_valid: Maximum number of valid schemas.
+    :param msg: Message to deliver to user if validation fails.
+    :param kwargs: All other keyword arguments are passed to the sub-Schema constructors.
+
+    :raises NotEnoughValid: if the minimum number of validations isn't met
+    :raises TooManyValid: if the more validations than the given amount is met
+
+    >>> validate = Schema(SomeOf(min_valid=2, validators=[Range(1, 5), Any(float, int), 6.6]))
+    >>> validate(6.6)
+    6.6
+    >>> validate(3)
+    3
+    >>> with raises(MultipleInvalid, 'value must be at most 5, not a valid value'):
+    ...     validate(6.2)
+    """
+
+    def __init__(self, validators, min_valid=None, max_valid=None, **kwargs):
+        assert min_valid is not None or max_valid is not None, \
+            'when using "%s" you should specify at least one of min_valid and max_valid' % (type(self).__name__,)
+        self.min_valid = min_valid or 0
+        self.max_valid = max_valid or len(validators)
+        self.validators = validators
+        self.msg = kwargs.pop('msg', None)
+        self._schemas = [Schema(val, **kwargs) for val in validators]
+
+    def __call__(self, v):
+        errors = []
+        for schema in self._schemas:
+            try:
+                v = schema(v)
+            except Invalid as e:
+                errors.append(e)
+
+        passed_count = len(self._schemas) - len(errors)
+        if self.min_valid <= passed_count <= self.max_valid:
+            return v
+
+        msg = self.msg
+        if not msg:
+            msg = ', '.join(map(str, errors))
+
+        if passed_count > self.max_valid:
+            raise TooManyValid(msg)
+        raise NotEnoughValid(msg)
+
+    def __repr__(self):
+        return 'SomeOf(min_valid=%s, validators=[%s], max_valid=%s, msg=%r)' % (
+            self.min_valid, ", ".join(repr(v) for v in self.validators), self.max_valid, self.msg)